Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Ni X.

Water quality pollutants, which may be generated due to various agricultural activities, can affect both surface water and groundwater resources. The objective of this study is to assess the effects of agricultural management practices and climate variability on surface water and groundwater using Soil and Water Assessment Tool (SWAT) model in the Big Sunflower River Watershed (BSRW), which is major concerned by its agricultural purpose in Mississippi. In addition, the MODFLOW model, a finite-difference groundwater model, was used to simulate groundwater flow with boundary, recharge and HRUs calculated from the corresponding SWAT model. A coupled SWAT-MODFLOW model was applied to evaluate the water quality and quantity effects due to different agricultural management practices. The SWAT model was calibrated and validated by comparing monthly stream flow to observations from USGS gaging stations with both R2 and Nash-Sutcliffe model efficiency coefficient up to 0.67. Statistics increased first and then decreased with increasing hydraulic curve numbers. The model results are expected to be better after the groundwater model is coupled and calibrated with groundwater level data. Different agricultural management practices will be applied to the coupled SWAT-MODFLOW model to evaluate the effects on water quality and quantity of surface water and groundwater.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Abu N.

Structural interpretation of aeromagnetic data and Landsat imagery over the Middle Benue Trough was carried out to determine the depth to basement, delineate the basement morphology and relief, and the structural features within the basin. The aeromagnetic and Landsat data were subjected to various image and data enhancement and transformation routines. Results of the study revealed lineaments with trend directions in the N-S, NE-SW, NW-SE and E-W directions, with the NE-SW trends been dominant. The depth to basement within the study area was established at 1.8Km, as shown from the spectral analysis plot. The Source Parameter Imaging (SPI) plot generated showed the central-south/eastern portion of the study area as being deeper in contrast to the western-south-west portion. The basin morphology of the trough was interpreted as having parallel sets of micro-basins which could be considered as grabens and horsts in agreement with the general features interpreted by early workers. Major elements used as hydrological tracers (Na, K, Mg, Ca, Fe, S, P, Al) and trace elements (Co, Sr, Ba, Cr, Mo, Mn, B, Zn, Pb, Si, I) were analyzed from the groundwaters within the study area. Piper'sTrilinear diagram was used for the classification of the groundwater within the study area as Mg-Na-H₂CO₄ waters, SO₄-Cl-HCO₃ waters and HCO₃-Cl waters. Hydrogeochemical characteristics of the saline groundwaters were evaluated by means of physico-chemical analysis on the collected samples. Conventional graphical plots, principal component analysis and geochemical modelling techniques were applied to evaluate the geochemistry of the brines. The principal components extracted on the data matrix explained 100% of the total variance. The first PC explained 69.87% of the variance and accounted for the majority of the variance in the original data set. It is mainly participated by (Tempt, TDS, Ca, Fe, Mg, Na, P, Sr, Cl, Br and SO₄). The second PC is characterized by (eH, P and H₂CO₃) and accounted for 19.66% of the variance. The third PC, which accounted for 10.47% is participated by (pH, Sr, F, and P). A direct hydrochemical comparison of the analyzed saline water samples with standard seawater evaporation trajectory was used in the interpretation of the Bromide-chloride relationship, which showed a linear correlation, indicating that these waters might have originated from seawater that did not evaporate to the point of halite precipitation, consistent with the absence of any type of evaporite deposit in the trough. By combining the observed isotopic characteristics and the elemental analyses of the the groundwaters presented in this study, the origin of the brine/salt could be said to be marine, related to the embedded fossil seawater within the transgressive marine sediments (Asu River Formation and Eze-Aku shales), on one hand, and to the disseminated/precipitated salts within the regressive (sandstone/siltstone) interbeds of the Awe Formation, on the other hand. The up-flux movement of the groundwaters, in addition to surface meteoric input, is suggested to be the possible hydraulic process responsible for the dissolution and or leaching of disseminated salts, as well as the modification and remobilization of the embedded fossil seawater within the underlying sedimentary units.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Tagert M., Linhoss A., Rawson J.C., Sassenrath G.

Since the 1970's, groundwater levels in the Mississippi Alluvial Aquifer have decreased as the number of irrigated acres in the Mississippi Delta has increased. Today, there are roughly 18,000 permitted irrigation wells dependent on water from the Mississippi Alluvial Aquifer. As concern has grown over groundwater declines, farmers have been implementing more irrigation conservation measures, such as the use of surge valves and computerized hole selection, which improve irrigation application methods. Some farmers are also using soil moisture sensors to improve irrigation timing, although this can be cumbersome, especially if irrigating a large number of fields. The Mississippi Irrigation Scheduling Tool (MIST) is a web-based irrigation scheduling tool designed to help farmers manage and schedule irrigation in a humid climate. The tool provides an estimate of crop water use based on a "checkbook" approach that determines the water balance of the soil, plus water from rainfall or irrigation, minus water used by the crop or evaporated from the soil. Daily evaporation is calculated using the modified Penman-Monteith equation. The system automatically notifies the farmer if irrigation is required when the available soil moisture balance falls below a set threshold. MIST, which is being tested in selected areas in the MS Delta region, has a web interface that allows producers to access their information from anywhere through tablet computers or smart phones. This presentation will give an update on the MIST project and summarize progress to date.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Feng G.

Supplemental irrigation are becoming common practice in Mississippi to stabilize and increase crop productivity and quality after crop late vegetative growing season. Agriculture consumes 90% of consumptive water use, 80% is from groundwater, only 20% is from surface water in the US second largest annual rainfall state of Mississippi. In western Mississippi, groundwater levels are declining due to increasing groundwater withdrawal for irrigation. Mississippi Delta will face a serious shortage of water for agriculture. In eastern Mississippi, the groundwater is so deep and expensive to pump for irrigation, majority of growers choose using surface pond water for irrigation. Sustainable conjunctive use of surface and ground water resources for irrigation requires knowledge of crop water requirements and deficit (difference in precipitation and evapotranspiration). Therefore, water deficit of dominant irrigated crops, soybean, corn and cotton in Mississippi western Delta and eastern Blackland Prairie regions was estimated. Historical weather data in the two regions dating back to 1800 were analyzed using time series statistical models. The patterns of changes in air temperature and precipitation in the past and future were determined. The obtained trends and other results will help understand climate change and provide agroecosystem models with information to assess agriculture sustainability and competitiveness as affected by such climate change in the future. Water requirements of the three major crops in the two regions were calculated using Hargreaves method. Spatial and temporal probability distribution and frequency of water deficit in both Delta and Blackland Prairie were analyzed. As a result, we are able to forecast water deficit of each individual crop during every growing stage in the state of Mississippi for irrigation scheduling, drainage design, rainfall harvest planning, and agronomic management practice development to make most use of both ground and surface water resources.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Abera L.E., Surbeck C.Q.

Stormwater runoff occurs when precipitation flows over the ground. Increase in impervious land cover due to urbanization causes excess stormwater runoff and affects the quantity and quality of receiving water bodies. The use of Low Impact Development (LID) controls is highly recommended to reduce the excess volume of stormwater runoff. LID controls include infiltration techniques such as pervious pavements, evaporation, and storage techniques to reduce the volume of runoff. In this study, performance assessment results of pervious concrete pavement at the University of Mississippi Law School parking area will be presented. The Law School was constructed in 2009 and is adjacent to a privately owned recreational pond. There is a high volume of stormwater runoff from the university area going to the pond, which prompts the university to implement LID tools, such as pervious pavement. Multiple in-place infiltration rate tests, using the ASTM C1701/C1701M-09 standard, were conducted to evaluate the effectiveness of the pervious pavement. Based on the test results, the average infiltration rate of the pervious pavement is 45.14 m/hr, which is less than the desired rate. The U.S. Environmental Protection Agency's Stormwater Management Modeling Tool (SWMM) was used to model the area and to quantify the volume of runoff that can be expected from different intensity storms. Results show that pervious concrete is more effective for a low intensity, long duration storm than for a high intensity, short duration storm.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Kokabian B., Gude V.G.

Discharge of nitrogenous compounds from municipal and industrial wastewater effluents is of major concerns of today's world since it has negative effects including eutrophication and hypoxia in water bodies. On the other hand, an ongoing challenge to sustainability of wastewater treatment systems is to improve the energy efficiency and cost effectiveness in removing nutrient compounds. A solution to this challenge would be to use Anammox bacteria in devices called Microbial Desalination Cell (ANXMDC). ANXMDC is a promising technology which allows for simultaneous wastewater treatment and desalination of saline water with concurrent electricity production and nitrogen removal. Exoelectrogenic bacteria in the anode oxidize organic matter while autotrophic bacteria serve as biocathode to remove ammonia in an emerging anaerobic microbial process called anaerobic ammonia oxidation (anammox). For a proof-of-concept study, the ANXMDC was fed with synthetic wastewater as organic source in the anode chamber and anammox bacteria were used as biocathode. The ANXMDC produced 0.0896 V while 100% of ammonia (NH₃ as ammonium) and 88% of nitrite were removed from the cathode chamber with desalination efficiency of 53.66%. Our results demonstrate that effective batch acclimatization experiments enhanced electricity generation along with nitrogenous compound removal and desalination. This study shows that this system has potential for sustainable and cost effective treatment of nitrogenous compounds and energy recovery from wastewater.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Karki R., Tagert M., Paz J.

Irrigation can help increase crop yields, decrease risk, and provides an avenue for crop diversification in Mississippi. In the Mississippi Delta, where groundwater is the primary source of water for irrigation, the Mississippi River Valley alluvial aquifer is being mined at an average of 3,00,000 acre-feet per year and the amount of withdrawal exceeds the recharge rate leading to a reduction in groundwater levels. Nutrient loading from irrigation tail water is another major concern in the Mississippi Delta. It has been estimated that about 1.5 million metric tons of nitrogen are being transported to the Gulf of Mexico every year from the Mississippi River Basin resulting in eutrophic conditions that has led to the development of hypoxic zones. An On-Farm Water Storage (OFWS) system, which consists of a tail water recovery ditch and a water storage pond, is a constructed BMP that has a primary goal of water conservation by capturing surface runoff from excess rainfall and irrigation tail water. This paper will describe an OFWS design and discuss the differences in OFWS establishment in the Mississippi Delta and East Mississippi based on irrigation techniques and tail water recovery systems. Preliminary findings on the difference in nutrient content of the storm water runoff and storage pond will also be discussed.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Omer A.R., Czarnecki J.M.

The Lower Mississippi Alluvial Valley is economically important due to its highly productive agricultural land. However, producers in this region face two predominant environmental issues that are inherently linked to the intensity of the agricultural industry in this region. First, intensive agriculture practices which have resulted in increased surface transport of nutrient-laden sediments, contributing to eutrophication in receiving waters and to the Gulf of Mexico Hypoxic Zone. Second, current water withdrawals from the Mississippi Alluvial Aquifer for irrigation are not sustainable. These issues threatening environmental resources necessitate use of best management practices and groundwater conservation. This research investigates systems of best management practices as water resource conservation methods. Such practices include surface water capture and irrigation reuse systems. Referred to as tailwater recovery systems (TWR), this practice consists of a tailwater recovery ditch which may be paired with on-farm storage reservoirs (OFS). Five case studies of different TWR were monitored for nutrients during a single growing season at: inflow, edge of field, TWR, OFS, and overflow locations. Investigations highlight functionality for nutrient recycling, and descriptions of nutrient loss mitigation. Additional research includes quantification of nutrients lost and captured during rice patty drains into TWR using in-situ nitrate sensors. Although research on these systems continues, initial results from three TWR in 2013 show over 278 million liters of water being recycled applying a mean of 0.96 kg/ha total nitrogen and 0.15 kg/ha total phosphorus. These systems are proving successful in holding water on the landscape, recycling that water, and therefore nutrients. Thereby preventing those nutrients from being lost to downstream waters. This suggests that TWR have much promise for water resource conservation in the Lower Mississippi Alluvial Valley.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Czarnecki J.M., Omer A.R.

In the State of Mississippi, the USDA via the Natural Resource Conservation Service has provided financial assistance for ~200 tailwater recovery systems (TWR) with and without the addition of an on-farm storage reservoir (OFS); over half of these systems are located within Sunflower County, overlying the cone of depression. The objective of this study was to quantify capture and use of TWR (and OFS, where available). In order to understand the water quantity benefits of TWR and OFS, it was necessary first to determine how much water these systems captured over the course of the year and how much water was lost from these systems due to natural processes. Working with agency partners, a list of TWR and OFS was compiled and 30 sites (18 TWR/12 OFS) were selected for study. Each site was instrumented with a water level logger. Loggers were set to capture data at 15-minute intervals. Loggers were deployed for at least a year in most systems. Dimensions and build specifications for each system were obtained to convert depth measurements into volumes. Incremental changes in volume and surface area were calculated for the span of the data collection effort. Considerations for evaporation and infiltration were made using best available models and methods to quantify these losses. These resultant values can then be weighed against the potential levels of capture, re-use, and loss, and the conservation contribution of TWR and OFS can be quantified. It is intended that these values will provide insight for agency personnel to determine if the benefit justifies the cost relative to other, alternative best management practices.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Diehl T., Cartwright J.

Water-quality improvement practices, including sediment retention and channel restoration projects, are commonly hampered by incomplete knowledge of sediment-source locations and transport networks within watersheds. In particular, gully systems can undermine infrastructure and pose public safety hazards through active bed and bank erosion and excessive sedimentation near their outlets. High-resolution digital elevation models (DEMs) from Light Detection and Ranging (LiDAR) are a newly-available data source useful for investigating geomorphology of stream channels and gullies. Channel and gully networks derived from these DEMs offer much higher resolution than currently available topographic maps or map-derived stream networks. The U.S. Geological Survey is working in cooperation with the Tennessee Department of Transportation and the Southwest Tennessee Development District to develop automated tools to identify locations of erosion, sediment transport, and deposition within channel and gully networks, based on landscape characteristics derived from high-resolution DEMs. By automating the identification of hotspots of channel erosion (for example incised channels and gully heads) and sedimentation (for example over-widened shallow channels and valley plugs) this project will provide a tools for local and regional efforts related to water quality, channel restoration, infrastructure protection, and storm-water management.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Frey B., Ouyang Y., Stoll J.

Over the last several decades, bottomland restoration efforts have established hundreds of thousands of acres of planted hardwood stands across floodplains of the Lower Mississippi Alluvial Valley (LMAV). Major goals of these afforestation efforts are to restore forest cover for the enhancement of wildlife habitat, soil conservation, and water quality. However, few studies have evaluated the effects of bottomland afforestation on soil and water quality, particularly in relationship to different sites conditions, planting mixtures, and over time as these afforestation stands mature. Studies have suggested that bottomland forest restoration could play an important role in carbon and nitrogen removal, particularly in connected floodplains in the LMAV. This presentation will review our research investigating stand development, growth and biomass of young (10-20 year old) planted oak stands and management activities that are being considered for these stands. We will also discuss our proposed research to investigate soil and hydrological processes in relation to stand development. Knowledge of stand growth, linked with soil and hydrological processes, is needed to evaluate the role of bottomland afforestation efforts in enhancing soil and water quality. This information will be important for addressing the impacts of these forest restoration efforts and identifying opportunities to improve their efficacy.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Macy A., Cebrian J., Cherry J.

With milder winter temperatures, the black mangrove Avicennia germinans has been expanding its range poleward into temperate salt marshes, forming an ecotone of mixed vegetation between two ecosystem-defining vegetations (Mangrove forest and Spartina salt marsh). In stable conditions, Avicennia outcompetes Spartina alterniflora, while occasional disturbances favor Spartina. Restoration efforts along the northern Gulf of Mexico will need to account for these interspecies interactions, and understanding stress tolerance thresholds of the climax species (Avicennia) in the field may offer an accelerated path to ecosystem stability and faster return on ecosystem services. I will transplant two groups of seedlings, aged 6-12 months old and 18-24 months old, into high and low energy wave environments. There are several created wetland areas in Bayou Lafourche (LA) dominated by early stages of wetland colonizatio (i.e. Spartina alterniflora). Spartina has been suggested as a wave buffer f Avicennia, aiding in the succession to an Avicennia-dominated system, so treatments will also include areas where Spartina has been clipped. Finally, fertilizer will be applied to half the plots to stimulate a decrease in the root: shoot ratio, possibly making Avicennia more vulnerable to uprooting from waves. Project scheduled to start this summer.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Oldham L., Cox M.S., Ramirez-Avila J., Kingery W.L.

Phosphorus (P) management presents a conundrum in the diverse soils of Mississippi. This required plant nutrient is naturally abundant in bioavailable forms in many alluvial plain region soils (Delta), yet native soil P levels restrict productivity in some Coastal Plain region soils. However, some Coastal Plain and Jackson Prairie soils have elevated bioavailable P from past management with copious amounts of animal production by-products. Phosphorus movement from soil to surface waters is implicated in environmental degradation such as Gulf of Mexico hypoxia, yet P fertilizers are not widely used due to high levels of native labile P in the Delta. There exists a need for better understanding P properties and dynamics to improve nutrient and landscape management so the appropriate management practices are targeted to specific, unique regions of Mississippi. In this paper we review, using molecular to landscape scales of reference: P forms found in soils and surface waters, the relevant chemistry, plant uptake mechanisms, and movement in the landscape. The implications for management will be discussed.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Rabalais N.N.

The world's climate has changed and human activities will continue to contribute to the acceleration of greenhouse gases and temperature rise. The major drivers of these changes are increased temperature, altered hydrological cycles and shifts in wind patterns that might alter coastal currents. Increasing temperatures alone have the potential to strengthen pycnoclines in estuarine and coastal waters, but lower surface salinity (e.g., from increased freshwater runoff) would be more of a factor in stratifying the water column. The combination of increased nutrient loads (from human activities) and increased freshwater discharge (from GCC) will aggravate the already high loads of nutrients from the Mississippi River to the northern Gulf of Mexico, strengthen stratification (all other factors remaining the same), and worsen the hypoxia situation. Reduced precipitation, on the other hand, would lower the amount of nutrients and water reaching the coastal zone and, perhaps, lead to oligotrophication and reduced fisheries productivity, or perhaps alleviate hypoxia. The increase or decrease in flow (whichever occurs), flux of nutrients and water temperature are likely to have important, but as yet not clearly identifiable, influences on hypoxia. In anticipation of the negative effects of global change, nutrient loadings to coastal waters need to be reduced now, so that further water quality degradation is prevented.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: West L., Moody R., Cebrian J., Aronson R., Heck K., Byron D.

Trawls and fyke nets are common sampling methods used in aquatic ecosystem studies. Sampling by trawls, which can be used to target seagrass-associated communities, is fundamentally different from sampling with fyke nets, which are positioned at fringing marsh edges to passively collect marsh organisms as the tide recedes. Thus, the two methods potentially differ in efficiency with respect to the numbers and types of organisms they can collect. In this study, we use a two-year data set to compare the community structure of marsh- and seagrass-associated nekton among five sampling sites in the northern Gulf of Mexico. We compare four metrics among sites, habitats, and sampling equipment: (1) total nekton abundance; (2) total abundance excluding the daggerblade grass shrimp Palaemonetes pugio, which is a numerically dominant species that may mask abundance patterns of other species; (3) total abundance of blue crabs and penaeid shrimp, the most abundant species after P. pugio and of commercial importance; and (4) nekton community structure. Variations in community structure between these aquatic habitats are discussed in light of differences in gear efficiency and inherent differences in the structural complexity and accessibility of each habitat to mobile fish and invertebrates. Our findings contribute to an emerging understanding of the potential for functional redundancy between fringing salt marshes and seagrass meadows, with emphasis on implications of this redundancy (or lack thereof) for commercially important species.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Welch H.

Depth- and- width- integrated isokinetic sampling techniques have been used to collect suspended-sediment samples in the Mississippi River by the U.S. Geological Survey (USGS) since the early 1970s as part of the National Stream Quality Accounting Network program. Collecting water-quality samples is critical in order to measure and understand chemical and sediment transport, but sampling can be challenging in terms of logistics, cost, and safety. The USGS has established suspended- sediment sampling protocols to ensure that samples are collected in a consistent and uniform way in streams across the country for data comparability and interpretation. However, variants of the traditional method have evolved to account for possible loss of equipment, improved safety to personnel, and potential loss of samples "contaminated" with bed material. Questions have recently arisen regarding the comparability of suspended-sediment data at selected water-quality stations along the lower Mississippi River. Three methods of sample collection have been used since the early 1980s. They include the traditional method, in which the sampler is lowered to the bottom of the channel, and two variants of that method, which consist of either lowering the sampler to 90% of the total stream depth or lowering the sampler to 2 feet from the bottom of the channel. From April through August 2013, the USGS collected suspended-sediment samples along a transect of the Mississippi River above Vicksburg, Mississippi using the three different methods. The collected data will be used to assess if: (1) sample collection techniques are reproducible, (2) data collected using the three different methods are comparable, and (3) the traditional method biases the suspended-sediment sample toward the sand-size fraction.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Welch H.L., Rose C.E.

Water-quality of the Mississippi River Valley alluvial (MRVA) aquifer has the potential to influence water quality of streams located in the lower Mississippi River Valley either through irrigation runoff from fields during the growing season (May through August) or at times of baseflow when streams are comprised of mostly groundwater. Previous studies of groundwater from the MRVA aquifer have shown concentrations of total dissolved phosphorus ranging from 0.12 to 1.2 milligrams per liter (mg/L). These concentrations exceed 0.1 mg/L, which is the desired goal established by the U.S. Environmental Protection Agency for the prevention of nuisance plant grown in streams. In addition, watersheds in the lower Mississippi River Valley have been identified as having some of the highest total phosphorus yields in the Mississippi River basin, although application of phosphorus fertilizers to land in the basin is minimal. The contribution of phosphorus from the alluvial aquifer to the total phosphorus loads in the basin has not been determined. From June through September 2014, the U.S. Geological Survey conducted a study near a rice field located in Issaquena County, Mississippi, to quantify the effect of irrigation runoff on water quality in a small ditch draining the field. Thirteen groundwater samples were collected from a well screened in the MRVA aquifer used to irrigate the rice field. In addition, runoff samples were collected downstream of the well at two locations: (1) from a water furrow that drains the rice field and (2) from a ditch immediately downstream of the water furrow. All samples were analyzed for water temperature, pH, dissolved oxygen, specific conductivity, alkalinity, iron, manganese, orthophosphate, and total phosphorus. State and Federal agencies can use the results of this study to help with the establishment of nutrient reduction strategies in the lower Mississippi River Valley.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Kelly D.

The Yazoo Mississippi Delta Joint Water Management District (YMD) has conducted water use surveys for the past thirteen years to determine the amount of groundwater used from the Mississippi River Valley Alluvial Aquifer (MRVA). These surveys focused on cotton, soybeans, corn, rice, and catfish. Each year begins with roughly 180 sites for investigation. In an effort to determine the most efficient ways to irrigate these crops, irrigation methods for each site are recorded along with the total amount of groundwater used. Additionally, a cost analysis is performed for each site. Electric single crop wells are targeted for this study. Flow rates are obtained throughout the year. Total kilowatts from the electric meter are collected from the sites at least once each month giving YMD a total hours of well operation and cost factors. After an average amount of water per acre by crop is determined, YMD uses a Geographic Information System (GIS) to apply these estimates across the entire delta.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Burcham W.

A Step Pool Storm Conveyance (SPSC) system has been constructed to restore a severely eroded ephemeral drainage on a tributary to Joe's Branch within the D'Olive Creek watershed in Baldwin County, Alabama. The project represents implementation of one of the management measures recommended in a comprehensive watershed management plan (WMP) developed for the area. The SPSC project was primarily funded through a Section 319 (nonpoint source) grant from the Alabama Department of Environmental Management (ADEM) to the Mobile Bay National Estuary Program (MBNEP). Additional funding for the project was provided by the Alabama Department of Transportation (ALDOT), with the cooperation and support of many others. The objective of an SPSC system is to convert and dissipate, through storage pools and sand seepage filters, surface storm flow to shallow groundwater flow. SPSC systems typically are comprised of a series of shallow aquatic pools, riffle grade control, native vegetation, and an underlying sand/organic filter bed media. An SPSC system is intended not only to provide a stable drainage pathway for higher flows, but to attenuate and/or retain lesser flows and facilitate water quality treatment. SPSC systems have been used in other parts of the country. Notably, in Anne Arundel County, Maryland, there have been several applications spanning over a decade, and the County has developed specific design guidelines for their construction. However, to our knowledge, an SPSC or similar system has not been evaluated for the conditions found in the north Gulf coastal region of south Alabama This presentation will discuss the engineering design and construction of the SPSC demonstration project in Spanish Fort, Alabama. Participants will be presented with information to identify when and why a SPSC may be an effective measure to stabilize and enhance hydrologic systems. Post-construction stormwater monitoring as performed by the Geological Survey of Alabama (GSA) will be discussed, along with "lessons learned". In addition, participants will be presented with future projects where these measures are currently being planned using different constraints.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Roberts B.A., Barlow J.R.

In 2014, the U.S. Geological Survey (USGS), Mississippi Water Science Center, in cooperation with the U.S. Army Corp of Engineers, Vicksburg District, installed and instrumented a total of ten groundwater-streamgages throughout the Yazoo Basin. Each groundwater-streamgage collects and transmits, at minimum, stream stage, stream temperature, groundwater level, and groundwater temperature. Site instrumentation consisted of installing near-stream piezometers near existing or new streamgages. These piezometers house pressure transducers with temperature recorders and provide a means to measure and record periodic water-levels in order to check the continuous data from the logger. Each groundwater-streamgage is operated and maintained on a regular schedule (approx. 8 week interval), and all data are transmitted real-time to a project web page. Groundwater-streamgages provide a framework to document the spatiotemporal variability of groundwater and surface-water interaction. Data will be used to better understand the potential connectivity between the stream and the alluvial aquifer within the Yazoo River Basin and how connectivity affects water quantity and quality throughout both. This network will also help understand and quantify the extent that the interaction between streams and the alluvial aquifer has been affected by declining water levels in the alluvial aquifer.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Shoemaker C., Ervin G.N.

Intensive agricultural practices in watersheds have the potential to lead to high inputs of non-point source pollutants as a byproduct of nitrogen and phosphorus fertilizer applications. Excess amounts of these nutrients can lead to the eutrophication of receiving water bodies and cause water quality degradation at local, regional, and national scales. To combat this problem, wetland restoration is seen as a potential remediation strategy for reducing nutrient loads entering into larger water bodies. However, wetlands differ in their ability to remove nutrients, in part a result of the plant diversity within wetlands. This study examined natural and restored herbaceous wetlands across the northern Delta in Mississippi to determine drivers of plant community composition and their subsequent effect on water quality. Six naturally occurring wetlands along with 24 restored wetlands enrolled in the Wetland Reserve Program (WRP) were sampled across 12 watersheds stratified by expected nitrogen loads (based on USDA agricultural statistics data). Wetlands were visited in May and August of 2014, with species presence and abundance recorded at 50 sampling plots within each wetland. On the restored sites, redvine (Brunnichia ovata) and trumpet creeper (Campsis radicans) frequently were recorded at 50% or more of our sample points per wetland, while knotweed (Polygonum spp.) was common throughout. Additionally, woody species, such as buttonbush (Cephalanthus occidentalis), swamp chestnut oak (Quercus michauxii), slippery elm (Ulmus rubra) and other bottomland hardwood species were found in greater abundance on the six natural sites compared to restored sites. Ongoing analyses are aimed at investigating components of water quality that may be driving or driven by plant species composition in these wetlands.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Rawson J.C., Linhoss A., Tagert M.L., Sassenrath G., Kingery W.

Increasing reliance of crop producers on water for irrigation coupled with expansion of irrigated acreage has resulted in the overdraft of the Mississippi River Valley alluvial aquifer (MRVA). As water resources continue to decline, there is an immediate need for more efficient water management and greater implementation of water conservation practices. Mississippi's Natural Resource Conservation Service (NRCS) has been working with farmers to increase voluntary implementation of water conservation practices, but these systems often require financial input from the grower and take time to install and manage. The Mississippi Irrigation Scheduling Tool (MIST) uses a "checkbook" water balance calculation and offers producers a free online irrigation management tool that indicates a need for irrigation when the soil water available to the plant falls below the level needed for crop growth. The overall objective of this study has been to evaluate and refine data requirements and inputs needed to calibrate and validate of the model for testing on corn and soybean fields with differing management and soil types. Data collection has been ongoing since May of 2011. Watermark 200SS sensors and dataloggers have been used to continually measure and record soil moisture at six-inch depth increments to three feet at various sites throughout the growing season of each year. Soil water retention curves were generated for each field from detailed soil testing at each depth increment and used to convert soil tension data to actual soil water balance, which was then compared to the MIST-calculated soil water balance. In addition, comparisons were done between sets of soil moisture readings within the same field to characterize the precision of the measurements. Next Generation Radar's (Nexrad) four-kilometer precipitation data were used along with farm irrigation data to calibrate the model for a soybean field under pivot irrigation and a cornfield under furrow irrigation.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Ramirez-Avila J.J., Almansa-Manrique E., Jian Y., Ortega-Achury S.L., Laurens-Vallejo L.A.

A major activity in applied hydrology is the estimation of rainfall event runoff from ungauged small watersheds. The Natural Resources Conservation Service (NRCS) Curve Number method is used to perform different rainfall-runoff analyses for different land use and soil conditions around the world, such as the estimation of design floods for small hydraulic structures, and Best Management Practices to reduce agricultural non-point source pollution. Knowing that the calculated runoff is more sensitive to the Curve Number value than to the rainfall depth, estimation of the Curve Number values for local situations is pertinent. Observed rainfall-runoff dataset were used to estimate the Curve Number value for six different land use and tillage conditions (i.e. bare soil, pastures, conventional tillage, reduced tillage, no-tillage, crops rotation) in the Orinoquia region of Colombia and agricultural fields under reduced tillage in the Mississippi Delta region in the USA. The estimated Curve Number values for bare soil and no-tillage row crops, ranging from 61 to 72, were relatively similar than those tabulated Curve Number values determined on base of land use and soil types. Estimated Curve Number values for pastures and crop rotation (ranging from 42 to 67) were slightly higher, while for row crops under tillage practices (ranging from 72 to 81) were slightly lower than tabulated Curve Number values.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Ramirez-Avila J., Oldham J.L., Ortega-Achury S.L., Gallardo-Estrella R., Baker B., Alexander K., Locke M., Read J.J.

Nutrient and sediment runoff from agricultural fields is a critical problem associated with impairment of waterbodies in Mississippi and has generated a need to identify best nutrient management practices that minimize sediment and nutrient losses from fields, mitigating their contribution to a low-oxygen environment in the Gulf of Mexico. Environmentally safe and cost-effective implementation of quantified nutrient load reductions would require analysis of site-specific monitored water quality data that help producers to identify the most appropriate conservation practices for protecting or improving water quality. But lack of information in many regions regarding edge of the field and watershed monitoring for water quality and quantity and their associated costs, has promoted the use of qualitative and quantitative risk assessment models or tools to explore actions and policy alternatives for managing both water quality and quantity from intensive agricultural fields. National, regional and State nutrient reduction initiatives have indicated that the evaluation and selection of analytical tools (or risk assessment models) needs to be included as one of the strategies for designing, siting and assessing potential reductions from multiple management practices implemented within the Mississippi Delta, and subsequently, the Mississippi Upland and Mississippi Coastal regions. A Conservation Innovation Grant (CIG) project is being conducted to determine the existent need to assess and enhance the ability of existing risk assessment tools for improved cost-effectiveness of conservation practices, and enhance stakeholder's ability to make appropriate resource conservation decisions supported through such tools. This project supports specifications in the recently revised USDA-NRCS nutrient management standard (590) and state nutrient criteria. Preliminary results are presented on research to test and validate five quantitative (APEX, NTT, APLE, N-Index, and RUSLE2) and three qualitative (P-Index, N Leaching Index, WQ Index) risk assessment tools in fields from the Mississippi Delta and the poultry production area in South Mississippi.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Dakhlalla A.O., Parajuli P.B.

The Mississippi River Valley Alluvial Aquifer, which underlies the Big Sunflower River Watershed (BSRW), is the most heavily used aquifer in the state of Mississippi. Because the aquifer is primarily used for irrigating crops such as corn, cotton, soybean, and rice, the water levels have been declining rapidly over the past few decades. The objectives of this study are to (1) develop a calibrated and validated model using SWAT for streamflow and water table depths in the BSRW, (2) analyze the relationship and trends between evapotranspiration and groundwater recharge rates within the model, and (3) to model the effects of various crop rotation strategies on groundwater storage and recharge. The model performed well during the calibration periodR²= 0.53 to 0.68 and NSE = 0.49 to 0.66) and validation perio(R²= 0.55 to 0.75 and NSE = 0.49 to 0.72) for daily streamflow, which was achieved by the SUFI-2 auto-calibration algorithm in the SWAT-CUP package. The model also performed well in simulating seasonal water table depth fluctuations at the calibration sub-basin (R² = 0.58 and NSE = 0.56) and at the validation sub-basin (R² = 0.72 and NSE = 0.63). The crop rotation scenarios with rice planting resulted in the lowest groundwater storage (-8.3% to -9.6%) compared to the baseline crop scenario, which is due to the high irrigation rates of the rice crop. However, the rice crop rotations resulted in the highest increases of groundwater recharge rates (+19.4% to +59.5%), likely because of the response to the deficiency of groundwater needed for irrigation as well as the limited water uptake by the shallow rice plant roots. The crop rotations with corn and cotton resulted in the largest increases in groundwater storage (+9.6% to +26.7%), which is the result of the low irrigation rates as well as the short time period between planting and harvesting. The results of this study is expected to aid farmers and watershed managers to conserve groundwater resources, but still maintain crop production.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Guzman S., Paz J., Tagert M.

Declining water levels in the Mississippi River Alluvial Aquifer (MRVA) are due to the expansion of irrigated acreage and increasing water demand in the Mississippi Delta region, causing the need to develop forecasting tools and improve conservation measures. One of the tools explored in recent investigations is the Artificial Neural Network (ANN) that has grown in popularity in terms of its application in modeling and forecasting nonlinear hydrologic time series such as groundwater levels. For instance, a previous study demonstrated that an ANN with 2 hidden layers, 100 time delays and Bayesian Regularization training algorithm had the best model architecture that provided predictions of daily groundwater levels up to three months ahead. The effectiveness of ANN in forecasting daily groundwater levels depends on different input datasets as well as on the network learning capacity. An important step in the ANN development process is the evaluation of significant input variables, given that not all of them are powerful predictors of the model output. In this study, the performance of an ANN trained with a Bayesian Regularization algorithm and different input variable combinations was evaluated to determine the optimal model that can simulate groundwater trends up to three months in a USGS monitoring well located in Sunflower County, Mississippi. Nine years of daily groundwater level measurements were collected and partitioned into training and validation data sets. At the same time, input time series such as daily evapotranspiration rates, calculated by the Priestly-Taylor method, and daily precipitation were also partitioned into training and validation sets. The evaluation of the model performance under different input variables was based on the Mean Square Error (MSE) and correlation statistic estimations. The use of ANN with significant input variables provides useful information for the management of water withdrawals either per well or on a regional level in order to implement different conservation practices.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Adusumilli N., Davis S.

The need to safeguard water availability within Louisiana has become critical, not only to sustain the state's water resources, but also to the sustainability of sectors that depend on this important resource. Competition for surface and groundwater supplies in only increasing in the state due to many factors including demand from sectors like industry, power generation, public supply, aquaculture, increasing irrigated acreage of crops, and prolonged droughts periods. Hence, planning should be geared toward identification of strategies that ensure water availability for all reasonable present and future needs and promote conservation of water resources. Selection and/or implementation of a strategy depends on long-term objectives, economic concerns, and the willingness of the stakeholders to embrace the perspectives on water management. Thus, identification of strategies that include tools, practices, and policies that promote conservation and efficiency is critical to motivate adoption and reduce stress on aquifers, reservoirs, and other surface water sources. More specifically, the strategies should emphasize water conservation, economic incentives to conserve water, and public education. Potential benefits of improving water use efficiency include costs reductions, environmental protection, reduce losses and waste of water, and reduction in energy consumption. The strategies identified will provide planners and decision makers with the information needed toward developing a long-term statewide water management plan.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Caffrey J.M., Amacker K.S., Murrell M.C., Woodrey M.

Advances in technology have greatly increased our ability to collect water quality data over a variety of space and time scales. For example, commercially available data sondes deployed to collect time series of temperature, salinity and dissolved oxygen data can capture events from hourly (tidal and diurnal) time scales to seasonal time scales capturing freshwater runoff and algal blooms. Analysis of data from these long-term deployments provides insights into the relative importance of anthropogenic and external drivers on estuarine ecosystem function. Dissolved oxygen time series have been used to estimate daily gross production, respiration and net ecosystem metabolism (NEM). However, long-term estimates of primary production and ecosystem respiration are rare in the estuarine literature, yet they provide fundamental information about the trophic status of these sensitive environments. When collected consistently, this approach makes it possible to resolve long-term trends, but perhaps more importantly, it provides a historical benchmark against which future patterns may be evaluated. Grand Bay National Estuarine Research Reserve is a small and relatively pristine estuary in the northern Gulf of Mexico. Freshwater input into the estuary is primarily local runoff from bayous and tidal creeks, including Bayou Cumbest, Bayou Heron, and Bangs Lake Nutrient loading to Grand Bay is relatively small, with ambient nutrient concentrations often below detection. Primary production was calculated from diurnal dissolved oxygen data sonde data using Odum's open water method. Primary production and respiration was highest in the summer and rates of these processes were highly correlated. Despite interannual patterns in freshwater flow and salinity, variability in metabolic rates was low, perhaps reflecting shifts in the relative importance of benthic and phytoplankton productivity, during different flow regimes. Primary production and water column chlorophyll a in Grand Bay following a 2005 phosphorus spill was similar that from other years. The lack of stimulation by phosphorus is consistent with nutrient addition bioassay experiments performed at Bangs Lake and Point aux Chenes. Samples collected bimonthly showed that nitrogen rather than phosphorus stimulated phytoplankton growth at both locations.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Barlow J.R., Connor J.H.

The Mississippi River alluvial plain in northwestern Mississippi (referred to as the Delta), once a floodplain to the Mississippi River covered with hardwoods and marshland, is now a highly productive agricultural region of large economic importance to Mississippi. Water for irrigation is supplied primarily by the Mississippi River Valley alluvial aquifer, and although the alluvial aquifer has a large reserve, there is evidence that the current rate of water use from the alluvial aquifer is not sustainable. Prior to extensive use of groundwater for irrigation, the regional groundwater flow path generally followed the topography of the alluvial plain, discharging to the streams and rivers within the Delta. Presently, the regional groundwater flow path is intercepted by a large cone of depression in the central Delta with maximum drawdown occurring in Sunflower County, formed as a result of groundwater pumping for irrigation. Water-level declines have resulted in decreased groundwater discharge to streams to the extent that many stream reaches in the Delta are presently net losing streams throughout the year. These changes in flow to and from the aquifer have decreased the amount of water available within the alluvial aquifer and have diminished many ecosystem services provided by groundwater discharge to streams such as maintaining baseflow in streams, regulating stream temperature regimes for aquatic biota, and buffering the transport of contaminants through the streambed interface.

An effort is currently underway to update and enhance an existing regional groundwater flow model in order to develop and run conjunctive water management optimization scenarios. This effort is jointly conducted by personnel from the U.S. Geological Survey and the Mississippi Department of Environmental Quality through a memorandum of understanding between the two agencies. Key revisions to the model include updating the model through 2014 with the addition of more recent water use data, precipitation and recharge data, and streamflow and water-level observations.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Killian C., Schmitz D.

This research had two main objectives: quantify surface-water and groundwater interactions along a stream reach, and determine the hydraulic conductivity at the site where two reservoirs are proposed. The stream reach, located in the Pascagoula River Basin in southeast Mississippi, begins at Lake Okatibbee and terminates at Pascagoula, into the Gulf of Mexico. Four USGS continuous gauging stations provided more than forty years of stream discharge data for a hydrograph base-flow-recession analysis, which determined the baseflow component within the stream. The analysis showed that baseflow decreases along the stream reach and increases again before reaching the Gulf of Mexico. Thirteen borehole samples were collected at the sites of the proposed reservoirs in George County, Mississippi to determine the hydraulic conductivity of the sediments, which showed high a hydraulic conductivity. The reservoirs will help to maintain stream ecology as well as increase surface water storage for recreational and industrial purposes.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Stiles M.

The Yazoo Mississippi Delta Joint Water Management District (YMD) collects water level information from the Mississippi River Valley Alluvial Aquifer (MRVA) twice each year, once in April and again in October. These months are used to allow staff to obtain water levels before and after the groundwater irrigation season. Measurements are gathered from a network of 550 survey wells located throughout the entire Mississippi delta. Tablet computers configured with custom software are used by field staff to assist with data entry and quality control. The information gathered from each water level survey is incorporated into the YMD geographic information system (GIS). After the field work is completed for each water level survey, YMD uses GIS to create water level surface maps. These surface maps serve as the primary datasets used by YMD to create short and long term aquifer water level change maps. Additionally, GIS is used to create aquifer water volume changes. These changes are calculated annually from Spring to Spring and Fall to Fall. Additional changes are calculated for fall to spring representing aquifer recovery and spring to fall representing water withdrawals. The aquifer water volume changes are calculated then entered into a spreadsheet for graphing.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Lahiri C., Davidson G.R., Threlkeld S.T.

The floodplain of the lower Mississippi River is littered with oxbow lake-wetland systems supporting dense forests of bald cypress and tupelo gum. Fine-grained sediments infilling the oxbows form low hydraulic conductivity plugs that should minimize communication between surface water and underlying groundwater, and produce pervasive reducing conditions in the soils during flooding. In forested oxbows, however, extensive root networks and decaying fallen trees have the potential to produce zones of higher conductivity and preferential vertical flow pathways. Evidence of preferential flow paths has been documented in Sky Lake, an abandoned meander loop of the Mississippi River in northeastern Mississippi. Redox potential measured hourly over an 18 month period revealed isolated zones that became oxidizing when surface water levels exceeded one meter. Changes in groundwater levels in a well located inside the meander loop were also consistent with recharge from the overlying oxbow. Advective delivery of oxygen through portions of the root zone has the potential to enhance tree growth during periods of extended inundation. Several cypress trees have been outfitted to continuously monitor sap flow and radial expansion to identify possible links between growth and changes in soil redox potential that accompany changes in water depth.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Ouyang Y.

Among the world's largest coastal and river basins, the Mississippi River Basin (MRB) is one of the most disturbed by human activity. Changes in agricultural and forest practices, clearcutting in bottomland hardwood forests, and conversions from forests to agricultural lands are largely responsible for the increased nutrient, sediment, and other pollutant loads into the Mississippi River (MR) and the adjacent Gulf of Mexico (GOM). The excess nutrient load has resulted in the increased extent and severity of the seasonal hypoxic zones, the altered species composition, and the decreased overall health of aquatic communities in the MRB and adjacent GOM. Additionally, the elevated sediment load has been recognized as both a carrier and a potential source of contaminants in aquatic environments due to their adsorption of toxic constituents. In spite of numerous efforts have been devoted to investigating the relationships between the ecological and environmental consequences of deforestation and the benefits of reforestation, very few efforts have been devoted to scrutinizing and synthesizing the effects of reforestation on water quality in the MRB. This study was undertaken to investigate (1) impacts of deforestation on water quality (e.g., nutrients and sediments), and (2) effects of reforestation and forestry management practices on surface water quality. Synthesized the review findings, we have identified the relevant knowledge gaps and recommended future research needs to assist forest and water resource managers in making timely decisions for water quality improvements in the MRB and the adjacent GOM.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Runner M., Stocks S.

Understanding low flow characteristics of streams is a critical concern of State water resource managers. How streams react to drought or long periods of low flow can affect multiple water use issues such as irrigation, municipal and industrial water supplies, fish and wildlife conservation, and dilution of waste. Estimates of the 7-day, 10-year (7Q10) low flow for streams in Mississippi are used as basic criterion for permitting of both waste discharges and water withdrawals. It is assumed that 7Q10 adequately addresses assimilative capacity in the stream for dilution of pollutants and also protects aquatic life during low flow periods. Therefore, accurate estimates of 7Q10 low flow values and potential impacts to water quality and biological response are essential for proper management of the State's water resources to balance aquatic health with economic development. 7Q10 low flow estimates for Mississippi streams have not been updated since 1991. In addition, potential shifts in water quality during periods of low flow have been infrequently documented in Mississippi streams, if at all. Sudden changes in dissolved oxygen, pH, and temperature during low flow periods could have tremendous impact to biological communities in streams. Therefore, it is necessary to obtain both water quantity and quality data in streams to fully understand the impact of critical low flow periods. The U.S Geological Survey, in cooperation with the Mississippi Department of Environmental Quality, collected streamflow data at 33 locations in southwest Mississippi to improve the ability of resource managers to estimate streamflow at ungaged locations based on current flow conditions at nearby reference gages. These data will be used to update 7Q10 computations for streams in southwestern Mississippi and to help determine the potential effects of low flows on water quality in the selected streams A total of 292 site visits were made between August 12 and October 30, with each site visited up to 10 times. During the site visits, water level, stream discharge, and water-quality field parameters were measured and recorded. Additionally, at 25 sites, water-quality instruments were deployed to measure field parameters over a 24-48 hour period. There were 245 streamflow measurements made with flows ranging from 0.004 to 142 cfs. There were 290 sets of discrete water-quality field parameter readings and 25 sets of time-series water quality data collected.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: McLaughlin M.R., Brooks J.P., Adeli A., Jenkins J.N.

Nutrient management plans (NMPs) for confined animal feeding operations (CAFOs) require a record of N and P loads from manure land-applications, including irrigation with lagoon water. Mississippi regulations require nutrient records for lagoon irrigation water be based on at least one annual analysis. Research on swine CAFOs in Mississippi has shown that N and P levels in lagoon water, and the N:P ratio, follow predictable annual cycles, but vary significantly through the April to October irrigation season. Nutrient estimates based on a single annual analysis may not account for this variability and may over- or underestimate nutrient loads and yield inaccurate NMP records. The present study reports an improved method to more accurately estimate N and P loads in irrigation water from swine lagoons. Derived by analyses of data from Mississippi lagoons and other lagoon studies, the method used predicable annual cycles of N and P in lagoon water to fit lagoon-specific models and produce date-based data on nutrient levels. Data were converted to tables displaying estimated N and P levels in the lagoon water for each day of the irrigation season. The farm manager uses the calendar table to find estimated nutrient levels for the date of a respective irrigation event, multiplies those values by the volume of water applied per irrigated area, and enters the results in the NMP record. Similarity of curves from analyses of lagoons in Mississippi and other states suggests that the method can be applied using data from a single nutrient analysis for each lagoon. Although annual cycles followed polynomial models, the irrigation season could be reduced to simpler linear models. An interesting mathematical result from the seasonal linear model showed that lagoon water samples from early July, midway in the irrigation season, represented the average N and P levels for the season, therefore, making it possible to estimate N and P loads using the single analysis data without fitting the data to a seasonal model and calendar table. The accuracy of the single early July analysis approach without curve fitting and a calendar table was, however, dependent on lagoon water volumes being uniformly distributed throughout the irrigation season. Fitting a curve and producing a lagoon-specific calendar table was more accurate for estimating nutrient loads when irrigation events and volumes were not evenly distributed through the season. Both methods were more accurate than using a single analysis from early or late season nutrient concentrations.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Miller C.R., Kern T.

River and seaports are important assets for regional economic development. Many industries need to be located in close proximity or with efficient transportation connections to ports. Therefore, ports are important site selection factors for industrial attraction. The industrial site selection process typically involves an initial web-based screening of potential locations by consultants or internal real estate teams. Those few communities or states that appear to meet the criteria based on their websites are sent a Request for Information (RFI) seeking specific information. There is a final screening based on the RFI information before economic development negotiations begin so to be successful in industrial attraction certain information needs to be on a port's website or readily available. This research, which was part of the 2014 Mississippi Department of Transportation Statewide Port Needs and Marketing Assessment study, reviews the port related information requested from RFIs to compile a content analysis tool for evaluating port websites. Each of the 16 port websites in Mississippi and their associated economic development organization are evaluated using this checklist. Recommendations for marketing are developed that will improve industrial attraction and retention efforts by ports.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Johnson K.

Mississippi State University's Gulf Coast Community Design Studio (GCCDS), in partnership with the Land Trust for the Mississippi Coastal Plain (LTMCP) and with input from community leaders and residents, is developing a Watershed Implementation Plan for Rotten Bayou Watershed in Hancock and Harrison Counties, Mississippi. In addition to developing a written plan, the work includes extensive education, community outreach, and demonstration projects of best management practices. Meaningful engagement is critical both to address conditions that cause nonpoint source pollution and to develop a plan that has good community buy-in to ensure implementation. Innovative engagement approaches are necessary in Rotten Bayou Watershed for two main reasons. First, there is currently very limited public access to the Bayou so few residents in the watershed have a direct connection to or an appreciation of the waterways they impact. Second, there are essentially two "communities" that make up the watershed: Fenton/Dedeaux and Diamondhead. Fenton/Dedeaux is a rural community with many residents that have deep roots in the area. Diamondhead is a planned retirement community that recently became Mississippi's newest city and is made up of many transplants to the area Effectively communicating with residents in these two communities; appealing to their different interests and values; and uniting them in the cause of improving water quality in Rotten Bayou requires multiple and creative approaches to outreach. The presentation will introduce conference attendees to the unique planning and outreach methods being utilized in developing the Rotten Bayou Watershed Implementation Plan. Strategies include working with non-traditional partners such as a churches, summer library reading programs, golf courses and an educational puppet show; utilizing social media and raffles to make participation appealing and accessible; and leveraging funding from NOAA's Gulf of Mexico B-WET Program to connect students at a local elementary school to the watershed planning work. The Watershed Implementation Plan for Rotten Bayou Watershed is funded in part by a grant from the EPA to the Mississippi Department of Environmental Quality under the provisions of Section 319(h) of the Clean Water Act along with State and local match.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Ingram R.B.

Humans are a terrestrial species, we're also a social species. Our activities impact all environmental media in which we live; surface and ground water quality and quantity, air quality, aquatic and wildlife habitat, ecosystem structure, and climate. In a recent national report on water quality in the United States, 45% of assessed stream miles, 47% of assessed lake acres, and 32% of assessed bays and estuarine square miles were classified as polluted. Mississippi's current 303(d) List identifies 21 impaired water bodies in the Coastal Streams Basin, Lower Pascagoula River Basin, and Lower Pearl River Basin. In this same area 45 TMDLs have been developed. During 2014, 44 beach closures and/or water contact advisories were issued. Water quality, ecosystem health, and human health are all inextricably linked. Backed by science, acknowledgement of this is reflected in the tiered surface water designated use categories inherent in Mississippi's water quality protection standards (public water supply, shellfish harvesting, recreation, and fish and wildlife) all designed to collectively protect water quality, ecosystem health, and human health. Likewise, a strong relationship exists between water quality and socioeconomics at all scales, from the individual to the local community to the larger society. A significant portion of the coastal economy depends upon water quality to support industrial development and the creation of jobs, for the maintenance of healthy ecosystems and harvesting of marine resources, and to sustain the Gulf Coast's traditions, cultures, and quality of life.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Linhoss A., Tagert M., Bukah H.

The Mississippi River Valley Alluvial Aquifer has seen dramatic declines due to pumping for irrigation in northwestern Mississippi. Irrigation scheduling saves water and energy without sacrificing yield through the optimal frequency and duration of water applications. Models, based on based on crop, soil, and climatic data, can be used for irrigation scheduling. The Mississippi Irrigation Scheduling Tool (MIST) is one such model. MIST uses the Penman-Montieth equation, along with crop coefficients, and the Soil Conservation Service curve number method to calculate runoff and evapotranspiration in a field. The resulting water balance can be used to schedule irrigation events. When using a model, such as MIST, for management purposes, it is important that the user be aware of the reliability or uncertainty of the model. Furthermore, model calibration can be optimized by identifying the most important driving parameters within a model. The objective of this research was to conduct a global sensitivity and uncertainty analysis of the MIST model to quantify model reliability and identify the most important model parameters. In order to provide a realistic representation of the model's uncertainty and sensitivity, parameter probability distributions were based on measured values and compared to results that used generic percentages. Six global sensitivity analysis methods were employed to understand how those methods differ (Sobol, FAST, Morris, random, quasi-random, and Latin-hypercube sampling). The results show that the sensitivity analysis methods return similar results. However, the method by which the probability distributions were determined were important in determining the results. These results are useful in developing better modeling tools and can help farmers and managers successfully apply MIST model recommendations.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Castillo C.

Watersheds in Mississippi provide many environmental and recreational benefits to the citizens and visitors of the state. The Nature Conservancy and the Pascagoula River Audubon Center are currently working to protect coastal Mississippi watersheds, in part through urban coastal preservation initiatives. The primary objective of this project was to aid these conservation efforts by delineating watershed extents for nine coastal streams within the three coastal counties of Jackson, Hancock, and Harrison. As these are small streams (<0.5 miles - 17 miles), most do not have individual watersheds delineated in the Watershed Boundary Dataset (WBD). Specifically, three analyses were conducted: watershed delineation of the urban streams, a Land Use Land Cover (LULC) map of the three coastal counties, and a wetland extent map of a subset of that area. The individual watershed delineation was conducted through open source Geographic Information Systems (GIS) platform Quantum Geographic Information System (QGIS) with the Geographic Resources Analysis Support System (GRASS) toolbar. These were then overlaid with watershed sub-basins created in ArcGIS for comparison. Earth Resources Data Analysis Systems (ERDAS) and QGIS were also used to perform a land cover classification. The analysis of wetland areas was performed using a Maximum Entropy (MaxEnt) model. Relevant inputs to these analyses included elevation, terrain aspect, thermal data, and vegetation indices. The analyses utilized Landsat 8 Operational Land Imager (OLI) data, and stream vectors. Our results reveal the distribution of wetlands, forests, and urban areas within these watersheds. Overall, this project illustrated the utility of open data, as well as open-source software. Furthermore, these watershed and wetland maps will aid in the current conservation efforts of endangered streams in southern Mississippi.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Castillo C., Crepps G.

Watersheds in Mississippi provide many environmental and recreational benefits to the citizens and visitors of the state. The Nature Conservancy and the Pascagoula River Audubon Center are currently working to protect coastal Mississippi watersheds, in part through urban coastal preservation initiatives. The primary objective of this project was to aid these conservation efforts by delineating watershed extents for nine coastal streams within the three coastal counties of Jackson, Hancock, and Harrison. As these are small streams (<0.5 miles - 17 miles), most do not have individual watersheds delineated in the Watershed Boundary Dataset (WBD). Specifically, three analyses were conducted: watershed delineation of the urban streams, a Land Use Land Cover (LULC) map of the three coastal counties, and a wetland extent map of a subset of that area. The individual watershed delineation was conducted through open source Geographic Information Systems (GIS) platform Quantum Geographic Information System (QGIS) with the Geographic Resources Analysis Support System (GRASS) toolbar. These were then overlaid with watershed sub-basins created in ArcGIS for comparison. Earth Resources Data Analysis Systems (ERDAS) and QGIS were also used to perform a land cover classification. The analysis of wetland areas was performed using a Maximum Entropy (MaxEnt) model. Relevant inputs to these analyses included elevation, terrain aspect, thermal data, and vegetation indices. The analyses utilized Landsat 8 Operational Land Imager (OLI) data, and stream vectors. Our results reveal the distribution of wetlands, forests, and urban areas within these watersheds. Overall, this project illustrated the utility of open data, as well as open-source software. Furthermore, these watershed and wetland maps will aid in the current conservation efforts of endangered streams in southern Mississippi.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Rebich R.A., Wilson D.T., Runner M.S.

The Mississippi barrier islands have undergone extensive changes in their formations over the past several decades primarily due to wind erosion and storm surge from hurricanes. In 1969 during Hurricane Camille, a "cut" formed through Ship Island bisecting it into what is known today as East and West Ship Islands. In addition, a tremendous amount of damage and erosion occurred on the two islands and to the shoreline of the Mississippi coast in the aftermath of Hurricane Katrina in 2005. In 2009, the Mississippi Coastal Improvement Program (MSCIP) was enacted by the U.S. Army Corps of Engineers (COE), in conjunction with other Federal and State partners, with the purpose of reducing future storm damage along the Mississippi Gulf Coast. MSCIP includes construction projects along the shoreline of Mississippi as well as major restoration efforts associated with the barrier islands. One such project is to restore Ship Island by filling in the "cut" (also known as "Camille Cut") between East and West Ship Islands thus creating one island again. The restoration effort to close Camille Cut and recreate a singular Ship Island could cause shifts in water quality and aquatic habitat in the vicinity of Ship Island and other areas within the Mississippi Sound. Of particular interest will be the potential increase in turbidity and suspended sediments during the construction phase. Adaptive management planning associated with MSCIP included establishment of a long-term monitoring network design to collect water-quality data to be used as indicators of change for comparison to biological response variables also collected during the study period, and to be used as input for modeling of the Mississippi Sound system to document longer-term change in response to restoration activities in the future. The U.S. Geological Survey (USGS), in cooperation with the COE-Mobile District, has implemented a water-quality monitoring network design in the Mississippi Sound to help achieve programmatic and adaptive management goals of MSCIP. Specifically, two locations near Ship Island have been outfitted to continuously monitor specific conductance (salinity), temperature, dissolved oxygen and turbidity. Nine locations located near Ship Island and near the remaining barrier islands will be visited eight times per year, and during each visit, the same water quality parameters are measured and discrete water quality are collected for nutrient and sediment analysis. This project is a 5-year project to include 1 year of pre-construction, 2 years of construction, and 2 years of post-construction data collection.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Cizdziel J., Bussan D.

Monomethylmercury (MMHg), a neurotoxin produced primarily by sulfate reducing bacteria in aquatic sediments, readily biomagnifies up the marine food chain. Consumption of fish containing high levels of MMHg can lead to adverse health effects in both humans and wildlife. This is of particular concern in the northern Gulf of Mexico (GoM) because, on average, residents of the Gulf Coast consume more marine fish than other U.S. residents, and because GoM fish tend to have higher levels MMHg than fish from other coastlines.^1,2 Moreover, because the economy of the Gulf coast states is intricately linked to the GoM through fishing (both commercial and recreational), understanding the distribution, levels and cycling of MMHg is vital to the long-term health and stability of the region. Whereas there has been much progress on understanding the fate, transport and transformation of mercury in aquatic and terrestrial environments, there remains a major gap in understanding of the sources and pathways of MMHg entry into food webs in the northern GoM. Recent advances in analytical techniques now offer an opportunity to answer fundamental questions such as where in the GoM is MMHg produced from inorganic mercury, and where is MMHg most bioavailable. Recent work demonstrates the potential of the use of enriched stable isotopes to simultaneously determine methylation and demethylation rates in sediments,3 and for stable isotopes to serve as probes for reaction pathways and to evaluate the source/history of mercury in samples.4 In this talk and associated poster, we will introduce these techniques and show how they can be used to advance our understanding of mercury cycling and transformation in the GoM. We will include recent results from our own research utilizing these techniques to study sediment from wetlands from the Mississippi Delta and from the cold seeps in the northern GoM.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Beard R.H.

The Gulf of Mexico Hypoxia Watch is a cooperative project of NOAA's National Marine Fisheries Service (NMFS), Southeast Fisheries Science Center (Pascagoula and Stennis Mississippi Labs), and NOAA's National Coastal Data Development Center (NCDDC). The purpose of the project is to collect measurements of bottom-dissolved oxygen using a Conductivity, Temperature, Depth (CTD) profiler with an oxygen sensor. The NOAA ship Oregon II goes to sea in June and July for the Southeast Area Monitoring and Assessment Program (SEAMAP) groundfish survey and collects the CTD measurements along with SEAMAP biological data. The CTD casts are done in a random pattern along the continental shelf, from the Texas/Mexico border to southern Florida, in water depths between 10 m and 200 m. After data processing, the bottom (deepest) oxygen values are sent via email to NCDDC where they are contoured and mapped. The contours show estimations of where high and low oxygen levels are likely occurring. The dissolved oxygen values range from 0 to 8 mg/L and the water is considered hypoxic if the value is 2 mg/L or less. During the cruise, values are often mapped daily, providing a near-real-time picture of the health of the Gulf. Currently, the Hypoxia Watch project includes data from 2001 through 2014. To access the data, view maps, or consult metadata for the project, please see http://www.ncddc.noaa.gov/hypoxia/.
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Final Project Report

Year: 2015 Authors: Davidson G.

Many oxbow lake-wetland systems in the Mississippi River floodplain are perched above the regional water table, resulting in a downward hydraulic gradient. Fine grained sediments that accumulate in these environments limit downward flow, but fallen tree trunks and limbs introduce heterogeneity and isolated pockets of higher hydraulic conductivity. Normally, flux is proportional to the gradient, but previous work by the PI suggested that the relationship between water depth and downward flow in these systems can be non-linear. Studies in Sky Lake, in the Delta region of Mississippi, have documented minimal vertical movement of water until a threshold water depth is reached. Above the threshold, abrupt changes in soil chemistry have been observed as water begins moving downward, which may in turn influence the growth of wetland trees. The role of oxbow lakes as points of groundwater recharge is also largely unknown. Though oxbow-lake bottom-sediments typically serve as barriers to flow, the heterogeneity that exists in the wetland perimeters may provide conduits for vertical flow that bypasses the surficial clay and silt deposits.

The project focused on the influence of changing water depth in Sky Lake, MS, in Humphreys County, where an elevated boardwalk into the heart of an old-growth bald-cypress wetland made it possible to mount equipment for long-term monitoring of a variety of environmental parameters (Fig. 1). The study focused on both the identification of non-linear responses to changing water depth, and its potential impact on tree growth and groundwater recharge. Possible non-linear downward flux in response to increases in wetland water depth was investigated using a series of redox probes at two depths in the sediment to monitor changes in redox potential that might accompany changes in water depth. Significant downward flow of oxygenated surface water should result in a shift to higher redox potentials. The impact on baldcypress tree growth was assessed using two sets of tree measurements: radial growth and sap flow rates. In order to link any changes in tree growth to water level, a series of additional variables were also measured that could also influence growth and mask a water-depth effect. These included temperature, relative humidity, and precipitation. Groundwater response was monitored by measuring the level of water in an abandoned irrigation well in the center of the oxbow meander loop.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Wade Steinriede R., Locke M.A., Testa S.

The Water Quality and Ecology Research Unit (WQERU) is part of the United States Department of Agriculture - Agricultural Research Service (USDA-ARS) National Sedimentation Laboratory located in Oxford, Mississippi. The stated research mission of the WQERU is to "address issues of water quality/quantity and watershed ecosystem function. Investigations pursue complimentary approaches that consider the entire landscape." This poster outlines some WQERU research that was designed to address issues relating to storm water and irrigation runoff associated with agricultural fields. Current research can be outlined in three main objectives: Objective 1) Evaluate farm and land management practices that have the potential to affect associated environmental issues such as sediment, nutrients, and water quantity. This type of research ranges from plot studies to monitoring and evaluation on the watershed scale. Objective 2) Characterize and quantify the structure, function, and processes of ecosystems associated with agriculture and their response to changes in land management. Objective 3) Perform integrated assessments of the effects of agriculture on ecosystem services for watershed-scale endpoints. This includes long-term watershed-scale monitoring programs along with modeling and using data collected from sampling and monitoring to improve the models. Through the use of a holistic grouping of studies, the WQERU is addressing needs for knowledge in the agricultural landscape.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Capps P., Surbeck C.

Man-made reservoirs are often used for both water supply and recreation. The Ross Barnett Reservoir in central Mississippi, a 33,000-acre man-made lake, provides drinking water to the city of Jackson, MS, and forty-eight surrounding communities. Further, an estimated 2.5 million people visit the reservoir each year for recreational purposes, including boating, fishing, water-skiing, and swimming. Protecting the water quality in the reservoir is important for these visitors and inhabitants along the shoreline, and for these reasons, the U.S. Environmental Protection Agency has selected it as a Priority Watershed in Mississippi. Presently, there is a concern regarding recent data collected that indicated increasing concentrations of bacteria in the Ross Barnett Reservoir. To detect possible harmful levels of bacteria in recreational waters, pathogen indicator monitoring is used. Sources of pathogens may include stormwater runoff, failing septic systems, lake-bottom sediments, and animals and humans in direct contact with the water. A collaborative study to investigate potential pathogen contamination in the reservoir is underway by the University of Mississippi, the U.S. Geological Survey, and the Mississippi Department of Environmental Quality. The goal of the study is to determine a method of pathogen indicator monitoring that takes less time than the standard 24 hours required by current methods for detecting bacteria. Such a method would improve the swiftness of notification to reservoir users when the water quality is not appropriate for contact. Pathogen indicators and other water-quality data such as water temperature, pH, turbidity, conductivity, dissolved oxygen, nutrients and solar strength, were collected at two recreational sites at the reservoir twice a week for 23 events through the spring and summer of 2013 as part of the collaborative study. Average concentrations for all E. coli, enterococci, and fecal coliform were 264 cfu/100mL, 175 cfu/100mL, and 298 cfu/100mL, respectively. The concentrations of pathogen indicators, nutrients, and values of physical parameters were statistically analyzed to provide insight about contamination sources. This research indicated that two water quality indicators of harmful bacteria levels in the water were turbidity at sites with low water circulation and days following rain events.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Janes L., Bowling T., Pennington D.

Over the last 30 years, withdrawals from the Mississippi River Valley Alluvial Aquifer (MRVA) have exceeded the aquifers natural ability to recharge resulting in a significant decline in the groundwater table in the Mississippi Delta. In an effort to decrease the overdraft of the MRVA, the Yazoo Mississippi Delta Joint Water Management District (YMD) has proposed implementing the Pecan Bayou Comprehensive Conservation Watershed to develop new water sources for irrigation water supply coupled with utilization of available conservation and management practices. Pecan Bayou is also a pilot planning component of a feasibility study with the USACE to import water into the Quiver River to enhance aquatic habitat and provide surface water for irrigation. This project has the potential to convert approximately 3000-5000 acres from groundwater to surface water irrigation and potentially offset the calculated overdraft within the project footprint. The project would consist of a re-lift station on the Quiver River to import approximately twenty-five (25) cubic feet per second (cfs) of surface water into the system for irrigation purposes. Imported surface water will be distributed through a network of improved natural channels and constructed zero-grade, lateral ditches. Weirs and water control structures will be constructed to divert and retain water in the system. The excavated channels and water control structures will not only provide water distribution and storage but also provide runoff recovery, improved drainage, and water retention. YMD also plans to implement available conservation practices, per landowner approval, to maximize the benefits of the system. YMD envisions the Pecan Bayou Comprehensive Conservation Watershed becoming a pilot-watershed to act as a blue-print for managing the natural resources of the Mississippi Delta.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Carmichael R.H., Darrow E., Wu W., Huang H., Calci W., Burkhardt W., Walton W., Pasch A.

We conducted a 4-year study to measure land-use related nutrient source and pathogen indicator changes through time using Grand Bay, on the Mississippi-Alabama coast, as a benchmark system. The study determined how land use changes in the past have affected water quality, natural resources, and potentially human health to provide data for local land use planning and decision-making. Data showed that historical and present-day land use, particularly increased wastewater and stormwater inputs to coastal areas, has affected water quality and potential for shellfish harvest. Of the five sites tested in the Grand Bay area, Bayou Chico in Mississippi was identified as having particularly poor water quality. Wastewater treatment was demonstrated as a method to reduce water quality impairment throughout the area. On August 1, more than 40 researchers, managers and members of the public met for a one-day workshop at the Grand Bay National Estuarine Research Reserve to discuss these findings and recommend data products to guide water quality improvements on the Mississippi-Alabama coast. Stakeholders identified two products as potentially most useful to promote water quality protection: a quantitative tool to predict how future land use change will affect water quality (nutrients and pathogens) and educational materials to raise awareness among local citizen groups, from eco-tourists to municipal officials. While full implementation of these products will take time, this workshop demonstrated that communication with stakeholders was useful to guide application of scientific data. To sustain water quality and shellfisheries safe for harvest, communities will need to balance land use, particularly area of impervious surface, with suitably designed wastewater treatment alternatives (e.g.; for runoff or combined sewage overflows) and water quality outcomes appropriate for natural resource and public health protection.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Appleton J.

Considering the projects that are the result of the Gulf Coast Restoration Act (GCRA), continued and on-going concerns with regards to water quality, agricultural and forestry activities, and the predicted impact of future warming on the rivers and streams of Mississippi, policy makers should consider a broad agenda of not simply providing water for future use and need, but these projects as the foundation of a new approach to the management of the states flowing water resources. These streams and rivers should not merely be considered for restoration, but for on-going mitigating management and development. In essence, in the context of warming temperatures, these resources are not and cannot be restored in the narrow sense, but can be managed in the dynamic sense. Such management should not be limited to, but could include wider civic participation in both the managerial goal setting, and in the care of the rivers and streams themselves. The rivers and steams should be evaluated with consideration for their ecosystems services, mitigation of the effects of a warming climate, and as the backbones of green corridors. Consideration should not include just the water itself, but the riparian ecology, the watershed, the management and perhaps the expansion and/or reintroduction of a range of species. The overall goal of future policies should be the provisioning and protection of water resources as part of a larger effort of environmental protection, and warming mitigation and adaptation.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Sui R.

Mississippi Delta is one of the most productive and intensively irrigated agricultural regions in US. Although there is more than 1000 mm of annual precipitation in this region, uncertainty in the amount and timing of precipitation is one of the most serious risks to the producers. Producers in this region have become increasingly reliant on supplemental irrigation to ensure adequate yields. There are more than 17,000 water wells in Mississippi Delta used to pump groundwater from the Mississippi River Valley Alluvial Aquifer for agricultural irrigation. Increasing groundwater withdrawal is resulting in a decline in the aquifer levels. It is necessary to develop improved water management tools for water resource preservation and sustainable agriculture in this region. To increase water use efficiency and productivity, novel sensing technologies are required to determine crop water status and conduct irrigation scheduling. Crop water status and the amount of supplementary water needed can be assessed by measuring soil moisture and plant physical response to water stress. A wireless sensor network (WSN) was built and deployed in three fields to monitor soil moisture status and collect weather data for irrigation scheduling. The WSN consists of soil moisture sensors, weather sensors, wireless data loggers, and a wireless modem. Soil moisture sensors were installed at three depths below the ground surface in various locations across the fields. Weather sensors were mounted on a 3-m instrument tower. An antenna mount was designed and fabricated for use in the WSN. When field equipment such as a fertilizer or chemical applicator impacted the mount, the mount was capable of protecting the antenna from damage by the equipment. The WSN has been deployed and operated in fields with cotton, corn, and soybean crops for three years. It performed well in data collection and transmission. No major operational issues occurred with the WSN except occasional data transmission interruptions by the thunderstorms during the summer. Using the WSN system, soil moisture and weather conditions including precipitation, solar radiation, wind speed, and humidity were measured every minute and the hourly averages were reported and stored at one-hour interval. The soil moisture data and weather data were automatically and wirelessly transmitted to the internet making the data available online. Data collected by the WSN have been used in irrigation scheduling research in cotton, corn and soybean crops.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Wilson G.V., Rigby J.R., Dabney S.M.

Flow through macropores can be sufficiently rapid to cause internal erosion and, thereby, create soil pipes. Soil pedology and hydrology interact to determine the location of soil pipes, flow rates through soil pipes and rates of internal erosion. Soil pipes tend to develop in duplex soil in that water restricting horizons cause a proliferation of biopores at the interface and foster lateral subsurface flow by perching water. Internal erosion can enlarge these preferential flow paths to the extent that soil pipe's collapse, thereby forming flute holes, sinkholes and ephemeral gullies at the surface. The soil hydropedologic properties determine the erodibility of the pipe surfaces and shear forces acting on pipe walls. Little is known about the impact of past land management practices on soil pipe formation. This paper will review the connections between hydrologic and pedologic soil properties and the impact of changes in land use from cropland to forest and forest to pasture on soil pipeflow processes using observations of soil pipes in Goodwin Creek Experimental Watershed. Three adjacent catchments, all classified as the same soil series, were surveyed for pipe collapse features. One contained no pipe collapse features, while the other two exhibited 32.6 and 15.7 collapse feature ha-1. Soils in these catchments contain a fragipan that perches water and fosters lateral flows. Subsurface layers exhibit vulnerability to internal erosion. It appears that past land management practices, including removal of forested buffers and filling in historical gullies control to a large degree the location of soil pipes and the current hydrologic response of the catchment. This paper will use field observations to highlight gaps in our understanding of the hydropedologic processes associated with soil piping and their interaction with and/or response to land management practices.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Bowling T., Janes L., Pennington D.

Over the last 30 years, withdrawals from the Mississippi River Valley Alluvial Aquifer (MRVA) have exceeded the aquifers natural ability to recharge resulting in a significant decline in the groundwater table in the Mississippi Delta. As water levels in the aquifer begin to drop, the dry season stream flows also begin to decline because less water is flowing from the aquifer into the streams. The portion of the aquifer underlying lands in close proximity to the Mississippi River are influenced by the fluctuations of water levels of the river system. During high and normal river stages, the Mississippi River can assist recharge of the groundwater aquifer near the river. During low river stages, groundwater from the aquifer can actually be lost by flowing back into the river. The Yazoo Mississippi Delta Joint Water Management District (YMD) has implemented and operated a working well field near Friar's Point, MS to better utilize Mississippi River recharged groundwater. Since 2005 YMD has used Mississippi River influenced groundwater to augment flows in the Sunflower River. Groundwater is extracted from a series of 11 wells and discharged into a tributary of Swan Lake. Water then flows through a water control structure at the Swan Lake outlet into a series of tributaries before joining the Sunflower River north of Clarksdale, MS. Pumps are operated in order to maintain a 50 cubic foot per second flow rate at the Sunflower, MS river gauge. Since 2012, YMD has monitored wells along the Mississippi River to develop a dataset in order to determine the extent of the Mississippi River's influence on the MRVA. By installing extraction wells in areas where the Mississippi River is in direct contact with the MRVA, well fields have the potential to capture clean, filtered Mississippi River water without adversely affecting the MRVA. Captured Mississippi River water can then be conveyed inland to aid in times of low flow to assist aquatic ecosystems and provide an abundance of surface water irrigation opportunities for the Mississippi Delta.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Ingram R.

A significant portion of Mississippi State University's (MSU) campus and property resides within the Catalpa Creek Watershed (referenced by USGS as the Red Bud-Catalpa Creek Watershed, HUC 12 #031601040601, and by MDEQ as MS #8090). This includes important MSU education and research facilities, such as the Mississippi Agricultural and Forestry Experiment Station's (MAFES) South Farm, which is used by numerous departments and programs. Unfortunately, some of MSU's land uses in this watershed may have contributed to the pollution of Catalpa Creek. Total Maximum Daily Load (TMDL) studies that apply to this watershed include those for sediment, nutrients, and pathogens. Each of these TMDLs recommend practices to reduce pollutant amounts to acceptable levels thereby providing improved habitat for the support of aquatic life and allowing for the attainment of applicable water quality standards.

On April 2013, MSU, through the Mississippi Water Resources Research Institute (MWRRI), was designated a Center of Excellence for Watershed Management with the signing of a Memorandum of Understanding (MOU) between the Mississippi Department of Environmental Quality (MDEQ), Region 4 of the U.S. Environmental Protection Agency (EPA), and MSU. The MOU recognized that MWRRI had "demonstrated to the satisfaction of EPA and MDEQ that it has the capacity and capability to identify and address the needs of the local watershed stakeholders" and was charged to "work with colleges and universities in Mississippi to engage students (graduate and undergraduate), faculty and staff from the full suite of disciplines needed to adequately address specific watershed issues" and to "draw upon other local, state, federal resources and expertise".

MWRRI, in its role as a Center of Excellence for Watershed Management, is advantageously positioned to bring resources together from various MSU departments and programs; nongovernmental organizations; and state and federal agencies to address the needs in the Catalpa Creek Watershed. This project will not only put appropriate BMPs on the ground in strategic locations in the watershed to restore water quality and habitat, but also establish a venue for watershed-based demonstrations, research, education, application and management.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Barrett J.

Mississippi has an abundant supply of underground aquifers which are utilized by community water systems as their source for drinking water. As the demand for water increases through the increasing population and the influx of industries, there is a need to manage the consumption and distribution of this valuable resource. The initial management forms created with the constructing of Mississippi's water supplies have experienced peaks and valleys of performance. Since their inception, the Mississippi drinking water industry has spawned new regulations, new management options, and creative ideas to promote a safer more efficient community water system. Over the past 15 years, Mississippi has seen several centralization efforts occur, where a municipality, utility district, or a rural water association merges with one or multiple adjoining or close proximity community water systems. This results in one of the three legal structures of a community water systems increasing in size in an effort to heighten performance. It will be valuable to see which of the consolidating government structures has been able to achieve optimal performance. This research analyzes the size (population) and government structures of Mississippi community water systems and will determine if economies of scale and economies of scope exist. This study will reveal the affect that size and government structure have on the overall performance of Mississippi community water systems.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Johnson D.R.

Mankind has been overdrawing its aquifers for more than 20 years in order to feed the ever expanding population. Is this a sustainable policy? In parts of the high plains aquifer of the U.S., many landowners who have been irrigating crops for over 50 years no longer can draw water from their wells. Closer to home in Arkansas, producers are now drawing water from the Sparta aquifer, which is generally reserved for drinking water, to supplement their withdrawals from the MAA for crop irrigation. USGS groundwater modeling studies show that the water level in the MAA will continue to decline for the foreseeable future. This presentation will discuss the actions the state or producers can take to reverse the decline in the MAA.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Locke M.A., Krutz J., Steinriede W., Dabney S.

Conservation management systems need to be assessed in the lower Mississippi River alluvial basin to balance production goals with environmental concerns. Complementary approaches for assessing effects of tillage and cover crops on water and soil quality in cotton (Gossypium hirsutum L.) production are reviewed here. In Study 1, no-tillage (NT) or minimum tillage (MT) with or without cover crop (rye [Secale cereale], balansa clover [Trifolium michelianum ssp. Balansae], or none) treatments were assessed from 2001 to 2006 for changes in soil characteristics and production. In 2007, a rainfall simulation study was conducted to evaluate treatment effects on runoff. In Study 2, NT, MT, MT with rye cover, and conventional tillage (CT) were assessed for effects on soil changes (2003 to 2011) and runoff water quality (2007 to 2011). Synthesis of results from these studies indicated that: (a) Cover crop and reduced tillage resulted in modest increases in soil organic matter and soil nitrogen; (b) Soil biological activity was enhanced by cover crops (e.g., enzymes, mycorrhizae); (c) Total runoff sediment loss was reduced by no-tillage and cover crop; (d) Nitrogen and phosphorus associated with runoff sediment were reduced in no-tillage and cover crop; (e) Soluble nitrogen and phosphorus in runoff was variable, sometimes higher in no-tillage and cover crop plots.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Faust D.R., Kroger R., Rush S.

Agricultural fertilizer applications have resulted in excessive nitrogen loading to agricultural drainage ditches, contributing to the Gulf of Mexico hypoxic zone. The purpose of this study was to assess relationships between organic carbon and nitrogen content of drainage ditches and evaluate the spatial scope in which organic carbon amendments may be used in remediating nutrient loading throughout the Lower Mississippi Alluvial Valley. Water and sediment samples were obtained from agricultural drainage ditches in Missouri, Arkansas, Mississippi, and Louisiana. Nitrate, nitrite, ammonia, and total nitrogen concentrations were determined in overlying and pore water, along with characterizing dissolved organic carbon aromaticity (spectral absorbance at 254 nm) and molecular weight (ratio of spectral absorbance at 254:365 nm). Concentrations of ammonia and nitrate nitrogen and total organic carbon in overlying and pore waters were variable, with ranges of 0.0117 to 20.4 mg L^-1, 0.05 to 17.0 mg L^-1, and 0.0 to 17.0 mg L^-1. However, concentrations of nitrogen species and dissolved organic carbon were generally higher in the pore water compared to those in overlying water. Pore waters generally had lower molecular weight character of dissolved organic carbon than overlying water, although this trend was dependent on the state and site from which the sample was collected. The results of this study show that there is spatial variability in nitrogen species and organic carbon throughout the Lower Mississippi Alluvial Valley and demonstrate the importance of evaluating where organic carbon may be limiting nitrogen removal in agricultural drainage ditches.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Rigby J.R., Locke M.A.

The Lower Mississippi River Basin is one of the most productive agricultural regions in the country links agricultural practices and associated runoff and nutrient loads from the Upper Mississippi, Missouri, and Ohio basins with the ecology of the Gulf of Mexico. In 2013 the USDA-ARS founded the Long-term Agroecosystem Research (LTAR) network consisting of 18 member locations across the United States to address long-term research and monitoring goals for U.S. agriculture. The Lower Mississippi River Basin (LMRB) is a member location of the network administered by the USDA-ARS National Sedimentation Laboratory. The LTAR network will focus activity on development of agroecosystem observatories with common standards for cross-site monitoring at all locations as well as a set of experiments to address the long-term sustainability of agriculture and the broader agricultural landscape in the U.S. A number of sustainability challenges face the Lower Mississippi River Basin including increased concerns around water quantity and quality issues.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Pennington D.

Recent development in electronic and software systems have made the use of small unmanned aerial vehicles (UAVs) practical for a wide range of applications. In the research presented here, an electric powered, 5 lb, 66 inch wing span, foam fixed wing model airplane was fitted with a 3D Robotics, APM 2.6 autopilot for guidance and two point-and-shoot Canon cameras for imagery collection. One camera is a 1.2 MP RGB camera and the filter in the second camera was changed to allow the red band to receive and record intensity of near infrared electromagnetic energy. Programmed flight missions were flown over 3 different fields at 100 meters above ground level or less. The same missions were flown over each field on several dates. The total number of individual images collected for each field ranged from 80 images for small plot areas to 325 images for a 65 acre production soybean field. Individual georeferenced tagged images were stitched into a single georeferenced orthophotograph mosaic for each field using the Dronemapper data system available commercially through the internet. Yield data was collected from the plot areas using conventional plot harvesting methods. Yield data from two production fields were obtained from yield data collected during harvest with combines fitted with yield monitoring systems. The remotely sensed imagery data and the spatial yield data were compared and analyzed with QGIS (free GIS software) and spreadsheets. Comparisons of spatial imagery and yield data are being made and the results of those analysis will be presented. Operational experience of a UAV system will also be discussed.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Pennington D.

Recent development in electronic and software systems have made the use of small unmanned aerial vehicles (UAVs) practical for a wide range of applications. In the research presented here, an electric powered, 5 lb, 66 inch wing span, foam fixed wing model airplane was fitted with a 3D Robotics, APM 2.6 autopilot for guidance and two point-and-shoot Canon cameras for imagery collection. One camera is a 1.2 MP RGB camera and the filter in the second camera was changed to allow the red band to receive and record intensity of near infrared electromagnetic energy. Programmed flight missions were flown over 3 different fields at 100 meters above ground level or less. The same missions were flown over each field on several dates. The total number of individual images collected for each field ranged from 80 images for small plot areas to 325 images for a 65 acre production soybean field. Individual georeferenced tagged images were stitched into a single georeferenced orthophotograph mosaic for each field using the Dronemapper data system available commercially through the internet. Yield data was collected from the plot areas using conventional plot harvesting methods. Yield data from two production fields were obtained from yield data collected during harvest with combines fitted with yield monitoring systems. The remotely sensed imagery data and the spatial yield data were compared and analyzed with QGIS (free GIS software) and spreadsheets. Comparisons of spatial imagery and yield data are being made and the results of those analysis will be presented. Operational experience of a UAV system will also be discussed.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Baker B., Kroger R., Prevost D., Pierce T.

Widespread concern for nutrient enrichment of freshwater and marine environments led to the formation of the Mississippi River/Gulf of Mexico Hypoxia Task Force, which aims to reduce riverine loads of total phosphorus from the Mississippi and Atchafalaya River Basins by 45% by 2015. Recent studies highlighted advantages of using low-grade weirs, situated in drainage ditches, to reduce effluent nutrient loads, as opposed to traditional control drainage practices such as variable height risers. The overall objective of this study was to quantify the effects of low-grade weir frequency and spatial arrangement on phosphorus and sediment reduction efficiencies of agriculture runoff using field-based experimental design in the Mississippi Delta. Low-grade weirs are an innovative, relatively low-cost and low-technology best management practice in comparison to large water reservoir systems or bioreactors, making them a suitable option for large and small-scale farmers alike. Study sites were located in the Yazoo Delta Region of Northwestern Mississippi. Results of the phosphorus and sediment load reduction efficiencies of low-grade weirs showed positive reductions in most ditches, with and without weirs. Low-flow and storm-flow outflow concentrations were found to be variable between sites, with no clear significant differences between sites with or without weirs. Mean percent differences between low flow and storm flow at each site resulted in low-flow samples having significantly lower phosphorus and sediment concentrations than during storm flows. A complimentary investigation of hydraulic retention highlighted that control ditches, while not engineered for such purposes, retained water. However, because this was an unintended consequence, these systems also exhibited flooding into producer fields; this phenomenon did not occur in ditches with weirs.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Barrett S., Beasley B., Wylie L., McDaniel B.

Coastal and migratory bird habitats in Mississippi are highly dynamic and constantly threatened by human activity. Today, these coastal and migratory species can be found on managed public lands. However, as of 2014, the Pascagoula River Audubon Center (PRAC) and the National Fish and Wildlife Foundation (NFWF) reported shorebird populations in coastal Mississippi have declined. In response, the Mississippi Audubon Coastal Bird Stewardship Program (CBSP) plans to focus habitat management on approximately twenty sites in coastal Mississippi. Activities includes planning and conducting standardized monitoring, implementing best-practice restoration projects, and a campaign to educate diverse audiences to increase understanding of the threats to and environmental and societal benefits of coastal and migratory birds. To support these efforts, this NASA DEVELOP project used current Landsat 8 OLI imagery to produce habitat classification maps that incorporated land use land cover, vegetation health, and water quality indices of areas in coastal Mississippi where these vital bird habitats are located. The project yielded maps for declining coastal bird species such as the least tern. End products and methodologies aided end-users in focusing habitat restoration efforts based on individual species' propensity to a particular area.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Barrett S., Beasley B., Wylie L., McDaniel B., Bosarge A.

Coastal and migratory bird habitats in Mississippi are highly dynamic and constantly threatened by human activity. Today, these coastal and migratory species can be found on managed public lands. However, as of 2014, the Pascagoula River Audubon Center (PRAC) and the National Fish and Wildlife Foundation (NFWF) reported shorebird populations in coastal Mississippi have declined. In response, the Mississippi Audubon Coastal Bird Stewardship Program (CBSP) plans to focus habitat management on approximately twenty sites in coastal Mississippi. Activities includes planning and conducting standardized monitoring, implementing best-practice restoration projects, and a campaign to educate diverse audiences to increase understanding of the threats to and environmental and societal benefits of coastal and migratory birds. To support these efforts, this NASA DEVELOP project used current Landsat 8 OLI imagery to produce habitat classification maps that incorporated land use land cover, vegetation health, and water quality indices of areas in coastal Mississippi where these vital bird habitats are located. The project yielded maps for declining coastal bird species such as the least tern. End products and methodologies aided end-users in focusing habitat restoration efforts based on individual species' propensity to a particular area.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Diaz J.

The goal of this presentation is show current water and environmental science programs developed at Alcorn State University. Alcorn State University - ASU, a Land Grant and Historically Black University located in southwest Mississippi, offers a Bachelor of Science in Agricultural Sciences with emphasis in Environmental Science. This program prepares highly skilled individuals for lifelong environmental career in private and public organizations. Students are trained to understand, investigate, and manage the environment and the many interactions among physical, chemical, biological, economical, and societal components towards a sustainable society. The program consists of 21% social science courses, 24% basic science classes, and 55% applied science subjects. Applied environmental classes include: water quality, concepts of environmental science, geographical information systems applications in natural resources, watershed hydrology, agricultural and environmental law. ASU's Mississippi River Research Center - MRRC is actively involved in mentoring and outreach activities which support the MRRC's mission in reaching out to students and general community as well as training the next generation of minority professionals in science and applied technology areas. Since January 2013, staff and students from the MRRC have prepared and performed eight outreach activities reaching about 200 school students. Through a National Science Foundation grant, the MRRC developed an environmental science activity manual and trained 16 middle-school teachers by providing content and hands on activities in three major themes: water, erosion, and environmental consciousness. Major accomplishments in student involvement include mentoring eight students; hosting two undergraduate students from Oberlin College, OH and University of Florida, FL through the NOAA-NGI Diversity Internship Summer Program; attending six professional meetings; and reaching third place in graduate poster competition in the 71st professional Agricultural Workers in Tuskegee University, Alabama. Currently, the MRRC is leading five projects funded by the State of Mississippi, US Department of Agriculture, US Forest Service, and Monsanto. Projects are focused on evaluating the temporal and spatial water quality variation and the indication of total coliform bacteria and Escherichia coli in four small lakes at ASU; assessing climate change impacts on southern Mississippi watersheds; measuring the acid neutralizing capacity of forest and aquatic ecosystems in Louisiana and Mississippi national forests; understanding factors influencing the adoption, efficiency, and impact of irrigation systems and scheduling methods for irrigation on small and limited resource vegetable and fruit farms in Mississippi; and promoting water quality management techniques for vegetable production. Summary of major project accomplishments will be presented at the conference.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Pérez-Gutiérrez J.D., Paz J.O., Tagert M.L.

Agricultural practices adversely alter the nutrients' natural cycle. The changes are due in large part to the dramatic increase in the use of fertilizers to support agricultural production. A substantial portion of nutrients is transported to groundwater and adjacent waterbodies via surface and irrigation runoff. This environmental issue is of special concern in the Mississippi River Basin, as it is the main source of nutrients that stimulate the development of the hypoxia zone in the northern Gulf of Mexico. To address this issue, Best Management Practices (BMPs) have been implemented with the aim of reducing nutrient loading from agricultural lands in the Mississippi Delta region. Recently, On-Farm Water Storage (OFWS) systems have attracted much attention because of their benefits to the environment, farmers and landowners. However, little is known about the watershed-scale impacts of these systems, as well as the effectiveness of OFWS systems in reducing nutrient loading downstream. This study discusses water quality changes in OFWS systems by analyzing the seasonal variability of several water quality parameters collected from OFWS systems at two farms in Porter Bayou watershed, Mississippi. Preliminary results reveal considerable differences in nitrogen and phosphorus concentrations between the influent and effluent water samples. The OFWS systems examined in this study show significant nutrient loading reduction downstream.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Dillon K., Caffrey J., Carmichael R., Holcomb S., Griffin C., Allen J., Jones T., Price K.

Bangs Lake, an estuarine water body in the Grand Bay NERR, has been the site of three industrial phosphate spills from a nearby fertilizer plant since 2005. Due to restricted tidal exchange in Bangs Lake, these events have had long lasting effects on water column phosphate concentrations which may stimulate biological activity and alter the biogeochemical cycling of essential elements within the water column and the sediments. To determine the fate of excess phosphate from the industrial spills, we measured soluble reactive phosphate concentrations in sediment pore water and total particulate phosphate concentrations from sediment cores (0-25 cm depth) from four locations: North Bangs Lake (closest to spill locations), Bangs Lake, and two low impact reference sites (Bayou Cumbest and Bayou Heron). We also conducted phosphate adsorption experiments and measured benthic chlorophyll concentrations with sediments from these sites to determine if the excess PO4 was fertilizing benthic microalgae to determine the fate of this excess PO4. Pore water phosphate concentrations were highest (21 uM) from 10 to 20 cm depths in North Bangs Lake cores however pore water from the surface sections of these cores had much lower phosphate concentrations (<0.5 uM). Pore water from the Bangs Lake cores consistently had elevated phosphate concentrations (2 to 5 uM) throughout the core length while pore water phosphate concentrations from one reference site were much lower (<0.7 uM), likely reflecting background levels. Phosphate adsorption experiments show that surface sediments from North Bangs Lake and Bayou Cumbest rapidly stripped phosphate from solution to final concentrations of <3 uM while surface sediments from Bangs Lake had greatly reduced phosphate adsorption capacity with much higher final concentrations (24 to 32 uM) indicating these sediments are near saturation. In 2013 and 2014, Sediment chlorophyll a concentrations were higher in Bangs Lake compared to the reference site. Sediment chlorophyll a was significantly correlated with extractable phosphate concentration in sediments (r = 0.88). In addition, grow out experiments with amendments of phosphorus to water and sediment samples stimulated the growth of cyanobacteria capable of fixing nitrogen.

Final Project Report

Year: 2015 Authors: Dillon K., Caffey J., Carmichael R.H., Cressman K., Woodrey M.

Bangs Lake, an estuarine water body in the Grand Bay NERR, has been the site of three industrial phosphate spills from a nearby fertilizer plant since 2005. Due to restricted tidal exchange in Bangs Lake, these events have had long lasting effects on water column phosphate concentrations which may stimulate biological activity and alter the biogeochemical cycling of essential elements within the water column and the sediments. To determine the fate of excess phosphate from the industrial spills, researchers measured soluble reactive phosphate concentrations in sediment pore water and total particulate phosphate concentrations from sediment cores (0-25 cm depth) from four locations: North Bangs Lake (closest to spill locations), Bangs Lake, and two low impact reference sites (Bayou Cumbest and Bayou Heron). Researchers also conducted phosphate adsorption experiments and measured benthic chlorophyll concentrations with sediments from these sites to determine if the excess PO4 was fertilizing benthic microalgae to determine the fate of this excess PO4. Pore water phosphate concentrations were highest (21 uM) from 10 to 20 cm depths in North Bangs Lake cores however pore water from the surface sections of these cores had much lower phosphate concentrations (<0.5 uM). Pore water from the Bangs Lake cores consistently had elevated phosphate concentrations (2 to 5 uM) throughout the core length while pore water phosphate concentrations from one reference site were much lower (<0.7 uM), likely reflecting background levels. Phosphate adsorption experiments show that surface sediments from North Bangs Lake and Bayou Cumbest rapidly stripped phosphate from solution to final concentrations of <3 uM while surface sediments from Bangs Lake had greatly reduced phosphate adsorption capacity with much higher final concentrations (24 to 32 uM) indicating these sediments are nearing saturation. Sediment chlorophyll a concentrations were higher in Bangs Lake compared to the reference site. Sediment chlorophyll a was significantly correlated with extractable phosphate concentration in sediments (r = 0.88). In addition, grow out experiments with amendments of phosphorus to water and sediment samples stimulated the growth of cyanobacteria capable of fixing nitrogen.

Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Ervin G.N.

Restoration of former agricultural land to wetlands, through programs such as the Wetlands Reserve Program (WRP) and Conservation Reserve Program (CRP), often focuses on restoring functions such as water quality improvement and wildlife habitat enhancement. However, results are inconclusive as to the long-term successes of these restorations. Our work is aimed at determining whether wetland restorations in the Mississippi Delta achieve sustained water quality improvements, and whether key water quality parameters are influenced by surrounding land use. During the summer of 2014, we assessed vegetation, land use, soils, and water quality in and around 24 restored and 6 naturally occurring wetlands across a gradient of human land use in the Delta. Initial analyses were based on classifying wetlands into watersheds with high, medium, or low levels of agricultural intensity, based on data from the USDA National Agricultural Statistics Service. We found differences in soils and surrounding land use of natural vs. restored wetlands but few differences attributable solely to our a priori classification of wetlands based on surrounding agricultural land use. When we examined correlations between water quality parameters and land use within 200m of the wetlands, we unexpectedly found no significant correlations. Nutrient concentrations were quite high in these wetlands; thus, it is possible that concentrations alone may be uninformative about impacts of surrounding land use. Additional work is planned to examine changes in water quality as surface waters move through these wetlands, as this may be a better metric of ecological function for Mississippi Delta wetlands.
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Proceedings of the 44rd Mississippi Water Resources Conference

Year: 2015 Authors: Pennington D.

The YMD Joint Water Management District was created in 1989 to develop and implement solutions to many of the Delta's water supply and quality problems. Heavy use of groundwater by agriculture has resulted in declining groundwater levels which are not sustainable and also contribute to loss of stream base flows. YMD has always recognized that efficient use of existing water supplies (conservation) and the development of new water supplies were the only non-regulatory solutions available to address the Delta's water supply problems. A simple spreadsheet model has been developed to provide 50 year scenario analysis of different conservation and water supply plans. The primary variables of the model are levels of conservation implementation, new water supplies and irrigation expansion. Results of the model indicate that, individually, conservation or new water supply will not have sufficient capacity to create a balanced water budget in the Delta. Both conservation and new water supplies will be needed if we continue to expand irrigated acres at historic rates. Following presentations in the session will go into greater detail about some of YMD's major efforts to collect water resources information to support planning efforts and our activities related to on-the-ground solutions.