Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Mamo T.G.

Climate change is a reality that planners and designers of drainage infrastructures must consider. The cumulative effects of gradual changes in hydrology due to climatic change are expected to alter the magnitude and frequency of peak flows over the service life of urban stormwater networks. Potential future changes in rainfall intensity are expected to alter the level of service of urban storm water networks, with increased rainfall intensity likely resulting in more frequent flooding of storm and surcharging of culverts.

The expected effects of climate change necessitate a change in the approach used to plan for and design urban stormwater networks. New development should ideally be served by both a minor storm drainage system, such as a traditional storm drainage system, and a major overland storm drainage system designed to convey the excess runoff when the capacity of the minor system is exceeded.

The planning and design of new urban stormwater networks should incorporate development features and sustainable urban drainage systems that provide multiple benefits such as a reduction of localized urban flooding and harmful environmental impacts, so the future urban stormwater networks design may be subject to a future rainfall regime that differs from current design standards.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Ervin G.N.

Coastal habitats being impacted by the Deepwater Horizon oil spill include beaches, barrier islands, shallow water habitats (seagrass beds and other submersed vegetation), and coastal marshes and estuaries. Some effects of this spill are obvious, but there are more subtle effects of the oil and dispersants that will cascade throughout coastal ecosystems of the Northern Gulf of Mexico, and unfortunately, little is known regarding those complex, ecosystem-level impacts. We are engaged in research that aims to improve understanding of environmental effects of oil and dispersant mixtures on shallow water habitats, wetlands, and beach sediments, and biological degradation of the oil and dispersant mixtures. Our approach is to assess early responses of intertidal habitats to oil/dispersant contamination, and interactions between oil/dispersant systems and soil/sediment microbial assemblages. Remote sensing analyses are being used to develop algorithms for diagnosing stress and/or dieoff of intertidal marsh vegetation. Multiple methodologies are being used to investigate impacts on microbial assemblages, including rates of incorporation of oil/dispersants into microbial biomass, metabolic shifts in the microbial assemblages, and factors influencing microbial metabolism of the oil and dispersants.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Tagert M.L., Ballweber J., Manuel R.

The Southeast Regional Small Public Water Systems Technical Assistance Center (SE-TAC), located at Mississippi State University and established via funding from the Environmental Protection Agency, is working with the City of Bay St. Louis and the Hancock County Utility Authority on an asset mapping and management demonstration project. This project builds on the implementation of Mississippi’s post-Katrina Gulf Regional Utility Plan and the creation of five (5) new county-wide utilities. This project will map the construction of the City’s post-Katrina water supply infrastructure and aid in its integration into the new Hancock County Utility Authority’s asset management system. The results of this effort will be immediately transferable to other coastal small public water systems and county-wide utilities in Mississippi. SE-TAC is working with the private sector to identify and assess public domain asset mapping and management tools. An evaluation matrix will be developed to compare various aspects of the available tools, such as hardware requirements, ease of use, expandability, training requirements, and more. The highest ranking public domain tool(s) will be applied to a defined subset of the City’s new drinking water infrastructure and integrated, to the extent possible, with the newly established Hancock County Utility. Results and lessons learned will be compiled in a final report to help accelerate adoption of asset mapping and management tools by small public water systems throughout Mississippi and the SE-TAC region.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Lawson A., Arnone R.A., Gould R.W., Scardino T.L., Martinolich P., Ladner S.W., Lewis D.

For calibration and validation, satellite products are often compared against in situ measurements. Over time, the satellite-measured data drift due to sensor degradation, resulting in errors of unknown magnitude: comparison against ground truth data allows the satellite sensor to be recalibrated. This process is known as vicarious calibration because pre-launch sensor calibration information can be adjusted once the complete system is operational in space. It is an essential component for any long-term satellite operation in order to ensure optimal accuracy in the satellite-derived products. We have developed an automated, continuous vicarious calibration system for satellite ocean color sensors (MODIS, MERIS, SeaWiFS) that employs a website interface to extract and visualize both satellite and in situ data. The data are graphed over time to allow instant visual comparison between the satellite sensor and the in situ data points and to help detect trends (drift) in the satellite measurements. In this case ,we are using the NASA Aeronet-OC sites, including those in the Northern Adriatic, Martha’s Vineyard, and the Gulf of Mexico. In addition, we are using multiple satellite resolutions to assess within pixel variation to allow further fine-tuning of the calibration factors and a better understanding of how the remote sensing data relates to the in situ truth. Various products are analyzed in the comparisons including the water-leaving radiance, remote sensing reflectance, chlorophyll concentration, and absorption, scattering, and backscattering coefficients. Because of the signal loss to atmosphere and water absorption of light with remote sensing, we consider two box sizes around the center satellite pixel that covers the Aeronet sites: a five-by-five box and a three-by-three box. Upon ingestion into our database various statistics are compiled on the data, including the standard deviation within the box, the mean, and the minimum and maximum values. These are used to generate error bars both spatially and temporally and detect outliers. With these statistics compiled daily and graphed in a time series format at daily, monthly, and yearly intervals, we are better able to understand sensors degradation through time and the impact on data retrievals; deviations between sensor-derived values and in situ measurements; the impact of varying sensor resolutions; and intercomparison of multiple sensors.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Brown G., Cizdziel J.

Mercury is a global health concern due to its toxicity, potential to bioaccumulation up the aquatic food chain, and global dispersion through atmospheric pathways. Mercury is mobilized through natural (e.g., volcanism, erosion) and anthropogenic (e.g., combustion of fossil fuels) means. Elemental mercury (Hg⁰), the most long-lived and stable form of mercury in the atmosphere, undergoes photochemical oxidation to the more soluble ionic mercury species (Hg²⁺), which falls to terrestrial and aquatic systems through wet and dry deposition. Sulfate-reducing bacteria, found primarily in low-oxygen aquatic environs, are capable of converting inorganic mercury to the neuro-toxic methylmercury (MeHg) form, which readily concentrates up the aquatic food chain. Human exposure to mercury is primarily through consumption of contaminated fish. In this study, results from a new methylmercury analyzer (Tekran 2700) will be presented. The system uses aqueous phase ethylation, gas chromatography, and atomic fluorescence detection. Samples were collected using clean techniques from areas in the Gulf Coast impacted by the oil spill, and from wetlands and groundwater in northern Mississippi. This poster will present relevant background, an overview of the instrumentation, and compare and contrast results for the saltwater and freshwater samples.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Johnson D.R.

The Delta Headwaters Project (DHP-formerly Demonstration Erosion Control Project) was initiated by Congress in 1984 in six Yazoo Basin headwater streams. The project has since been expanded into sixteen watersheds, which encompass over 6,800 square kilometers. DHP seeks to develop and demonstrate a watershed systems approach to address problems associated with watershed instability including: erosion, sedimentation, flooding and environmental degradation. DHP provides for the development of a system for control of sediment, erosion and flooding in the hill areas of the Yazoo River Basin, Mississippi. The project uses a variety of features for sediment control, which include: riser pipes, bank stabilization, and grade control structures. This study uses daily suspended sediment and discharge measurements from 16 sites to evaluate the effectiveness of DHP with regard to sediment control. The annual sum of these two parameters were calculated and compared by site. Most sites displayed a large decrease in the sum suspended solids over the life of the project. The ratio of the sum of suspended solids to discharge was also calculated. This ratio was used to adjust the suspended sediment changes with discharge. Again most sites displayed large decreases in this ratio over time. Hotopha Creek had a sediment:discharge ratio of 3.7 in 1987, which was reduced to 1.4 in 1997. This produced a reduction in the average daily sediment load from 111 tons/day in 1986 to 44 tons/day in 1997 under similar hydrologic conditions.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Irvin S., Paz J.O., Tagert M.L., Parajuli P., Cathcart T.

Assessing water quality on impaired streams helps determine the magnitude of its impairment and identify the exact location where the impairment is most severe. Advances in remote sensing and geospatial technology have allowed researchers and environmental agencies to assess streams by monitoring large areas. Using both in situ measurements and aerial imagery and comparing the differences can provide a more specific view on the streams health. The main goal of this study was to demonstrate the use of aerial imagery in detecting water quality indicators in impaired streams. A 3-mile segment of Tibbee Creek in Clay County, Mississippi, an impaired water body listed on the Mississippi 303(d), was selected for this study. Water samples were collected at different points along the river, with transects at each point between May and July 2010. The temperature differences and dissolved oxygen levels were measured at each transect. Samples were tested for turbidity, total suspended solids (TSS) and biological oxygen demand (BOD5). High resolution (0.5 m) aerial images that covered the entire study area were obtained in order to capture spatial differences along the channel. Preliminary analysis shows that turbidity readings were higher in the downstream segment of the river during the early part of testing and toward the end of testing. This was not the case during the middle of the summer and after rain events. Relationships between spectral bands and observed water quality parameters were used to estimate the water quality parameters at different locations of Tibbee Creek. The results of this research are expected to assist in the development of near real-time maps for the evaluation and monitoring of water quality of streams and rivers, providing large spatial coverage resulting in significant cost-savings over conventional in situ water quality.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Brzuszek R.F., Schauwecker T.J.

The mission of the Crosby Arboretum, Mississippi State University Extension (located in Picayune, MS) is to preserve, protect, and display plants and their communities in the Pearl River Drainage Basin. The Crosby Arboretum’s nationally award-winning master plan has designated a portion of its facility for the creation of a gum swamp educational exhibit. Gum swamp forests are semi-permanently flooded forests that are predominated in species type and frequency by black gum (Nyssa biflora) and tupelo gum (Nyssa aquatica). As specified in Mississippi’s Comprehensive Wildlife Conservation Strategy by the Mississippi Department of Wildlife and Fisheries (MDWF), Bald Cypress/Gum Swamp Forest Communities are considered vulnerable in the state of Mississippi. The proposed gum pond exhibit will address MDWF priorities through the construction and management of the exhibit; as well as providing a public venue for public education and experience for this vulnerable forest type.

The Crosby Arboretum Foundation was awarded a grant to create .5 acres of Arboretum property for a gum pond wetland exhibit. Graduate students in the Department of Landscape Architecture at Mississippi State University utilized a semester-long class project in spring 2010 to research and design the proposed gum pond exhibit. Students conducted a literature search on gum ponds and related wetlands and visited several in situ natural gum swamps in Mississippi. Students recorded environmental data at the natural wetlands to inform the restoration design. Students also conducted an environmental inventory and analysis at the proposed exhibit site that recorded the site’s hydrology patterns, plant species, soils, and other data. A design charrette, or a collaborative session to determine solution to the design problem, was conducted with wetland specialists and landscape architects to develop the preliminary design. This presentation will discuss the method used to develop the exhibit design and will exhibit the drawings for the proposed gum pond. Construction for the exhibit is slated to begin in summer 2010.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Spencer A.B., Kaminski R.M., D'Abramo L.R., Avery J.L., Kroger R.

Moist-soil wetlands in the Mississippi Alluvial Valley (MAV) are dewatered in spring through summer to promote production of grasses, sedges, and other herbaceous vegetation which are prolific producers of seeds and tubers for migrating and wintering waterfowl. Moist-soil wetlands are also potential sites for production and harvest of native crayfish (Procambarus spp.). Harvests of crayfish for human consumption in the United States amounts to $115 million annually. In springs 2009 and 2010, we harvested crayfish from moist-soil wetlands in Arkansas, Louisiana, and Mississippi. We harvested 92.2 kg of crayfish over 1,298 net nights in 2009 and 94.3 kg over 2,005 net nights in 2010. Mean daily harvest of crayfish from moist-soil wetlands was 1.75 kg/ha (CV = 16%, n = 9) in 2009, 1.25 kg/ha (CV = 17%, n = 13) in 2010, and 1.56 (CV = 13%, n = 22) for years combined. Whereas these yields are lower than reported for Louisiana cultured crayfish (i.e., 10 kg/ha), the economic value of native crayfish harvested from moist-soil wetlands may be significant to landowners considering the practice neither requires planting a forage crop for crayfish nor their capture and transport to rice fields. Additionally, within the MAV, strategic location of moist-soil wetlands amid farmed landscapes can reduce dispersal of sediments and other nutrients into surrounding watersheds. In July 2010, we installed water quality monitoring stations at six moist-soil wetlands and six adjacent agriculture fields in the Mississippi portion of the MAV. We will present preliminary estimates and comparisons of concentrations (mg L^-1) and loads (kg) of nitrate, NO_3--N; nitrite, NO_2--N; ammonium, NH4+-N; total phosphorus, TP; total dissolved phosphorus, TDP; particulate phosphorus, PP and; total suspended solids, TSS exported from moist-soil wetlands and agriculture fields. Quantifying these ancillary ecosystem services of moist-soil wetlands will encourage further establishment and management of these wetlands in the MAV and elsewhere for wildlife and associated environmental benefits.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Dyer J.

Agricultural production in the Mississippi Delta is critically dependent on precipitation; however, warm-season rainfall patterns within northwest Mississippi show that the Mississippi Delta receives a minimum of precipitation relative to adjacent regions. The reasons for this may be associated with gradients in heat and moisture fluxes along the eastern periphery of the Mississippi Delta arising from sharp changes in land cover. Using high spatial resolution simulations from the Weather Research and Forecasting (WRF) model, atmospheric patterns associated with defined non-frontal warm-season convective precipitation events are analyzed to determine the conditions related to rainfall modification in northwest Mississippi. Results show that decreased latent heat flux over the cultivated Mississippi Delta relative to adjacent forested land leads to an increase in localized lower atmospheric temperature. Combined with low-level moisture advection from the Gulf of Mexico, localized convection along the edge of the temperature gradient leads to precipitation generation and subsequent rainfall. Due to climatologically prevalent westerly flow over the region, this rainfall reaches the surface east of the Mississippi Delta. This defined pattern indicates that there is a potential for inter-basin water transport through atmospheric processes, leading to a decrease in precipitation over the Mississippi Delta due to local land cover characteristics. Future research on the quantification of the depth of water associated with atmospheric transport of moisture is imperative to defining regional water resource patterns in northwest Mississippi.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Welch H.L., Coupe R.H.

In the search for renewable fuel alternatives, biofuels have gained strong political momentum. In the last decade, extensive mandates, policies, and subsidies have been adopted to foster the development of a biofuels industry in the U.S. The manifestation of the Biofuels Initiative in the Mississippi Delta was a 47-percent decrease in cotton acreage with a concomitant 288 percent increase in corn acreage in 2007. Because corn uses 60 percent more water for irrigation than cotton, and more nitrogen fertilizer is recommended for corn cultivation, this crop type change has implications for water quantity and quality in the Delta. Increased water use for corn is accelerating water-level declines in the Mississippi River Valley alluvial aquifer at a time when conservation is being encouraged due to concerns about sustainability. A mathematical model calibrated to existing conditions in the Delta shows that increased fertilizer applications on corn will increase the extent of nitrate movement into the alluvial aquifer. Estimates based on surface-water modeling results indicate that higher application rates of nitrogen from increased corn production increases the amount of nitrogen exported from the Yazoo River basin to the Gulf of Mexico by about 7 percent; increasing the Delta’s contribution to hypoxic conditions in the Gulf of Mexico.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Rasmussen M., Orsi T.H., Dye T., Patrick D., Floyd I., Buck J., Carter G., Newcomb A.

Located in Perry County, MS, the Camp Shelby Training Site (CSTS) faces the challenge of meeting the ever increasing demands of military training to ensure combat readiness while adhering to numerous federal and state environmental laws and regulations. On occasion, training requirements result in unavoidable construction and/or operations within or around environmentally sensitive areas such as wetlands. As an example, construction of the Sonny Montgomery Multi Purpose Range Complex-Heavy (MPRC-H) adversely affected wetlands within its boundaries and resulted in the creation of the Cypress Creek Mitigation Site (CCMS) in the eastern part of the training site. The CCMS is located within the Cypress Creek Watershed that drains into Black Creek. Of the total 246.5 acres, the CCMS consists of 164.7 wetland acres and 81.8 acres of uplands. The CCMS was initially surveyed in 1999 and permitted by the US Army Corps of Engineers Mobile District in 2000.

Physiographically, the CCMS consists of three provinces. The Upland pine flat is characterized by very well drained, non-hydric, fine loamy sand with 55% FACU species, such as the longleaf pine (Pinus palustris). The slope province within the mitigation site is a well drained sandy loam that begins to exhibit stripping in the lower (6-8 inches) portion of the soil profile. This mixed pine-blackgum-oak forest contains 38% FAC and 15% FACU species. Wetland soils at CCMS are a hydric stripped matrix sandy loam that grades into a silty clay loam near a Cypress Creek tributary that traverses the site. This Cyrilla-Cliftonia-Nyssy bottomland is comprised of 39% OBL and 30% FACW species.

Restoration actions at the CCMS have consisted of removing roads and/or fire lanes that might impede water flow into the wetlands, controlled burning to remove unwanted species from both the wetland and upland areas, and removal of pine plantations in certain sections to allow native hydrophytic vegetation to recover or repopulate areas of historical wetland. After two controlled burns, the buckwheat (Cliftonia monophylla) and swamp titi (Cyrilla racemiflora) heavy shrub layer is beginning to thin allowing bald cypress (Taxodium distichum) saplings to emerge as well as numerous forbs and herbs that had been previously shaded out. At least one more controlled burn is needed for the understory to open completely. More recently, girdling has been considered as an alternative to downing large Pinus palustris individuals; the approach would reduce soil water demand, decrease overstory density, and create snag habitat for species that require it for nesting.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Mills M.C., Ervin G.N., Baldwin B.S.

The genus Arundinaria includes three species: Arundinaria gigantean (Walter) Muhl. (rivercane), Arundinaria tecta (Walter) Muhl. (switchcane) and Arundinaria appalachiana Triplett, Weakley, & L.G. Clark (hillcane). Arundinaria gigantean and A. tecta are both found in Mississippi, but in slightly different habitats. Arundinaria gigantean typically occurs on the floodplains of large to small rivers, sometimes on the edge of mesic slopes, while A. tecta usually occurs along small to medium blackwater rivers and in small seepages with organic soils. Thus, A. tecta usually is found on moister sites than A. gigantean. Our study assessed the responses of A. gigantean and A. tecta to different periods of inundation (0-week, 2-week, 4-week, and 6-week) under greenhouse conditions. Plant growth parameters, mean net photosynthesis (Pn), and stomatal conductance (Gs) were measured on a weekly basis for each ramet. At the conclusion of the experiment, cane biomass, including root and rhizome mass, were measured. Once flooded, Arundinaria spp. ramets in the 6-week flood treatment had lower Pn rates than those ramets not flooded. During the last week of flooding, A. tecta had a higher Pn rate than A. gigantean. Once flooding was stopped, A. tecta continued to have higher Pn and Gs rates than A. gigantean. Additionally, A. tecta grew more culms post-flood than A. gigantea. In conclusion, A. tecta appeared to be more flood tolerant than A. gigantea, in agreement with habitats in which A. tecta is known to occur. This research should contribute to improving the success of future canebrake restoration projects by increasing understanding of cane’s tolerance of inundation as well as aiding decisions of land managers choosing potential restoration sites or restoration species, based on hydrologic conditions.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Camacho R.A., Martin J.L.

The Estuarine Residence Time (ERT) is an important hydrodynamic-water quality parameter that evaluates the amount of time a substance remains in an estuary. The water quality of estuarine systems is often closely linked to the ERT. For example, estuarine systems with a low ERT are less vulnerable to algae blooms than estuarine systems with a higher ERT. Also, this parameter can be used to assess the characteristics of the transport of contaminants within estuaries as well as to evaluate the auto-depurative (self-cleansing) capacity of these systems.

This paper presents the results of an initial analysis of the ERT of the St Louis Bay Estuary, MS, using the linked hydrodynamic and water quality models EFDC and WASP. The computation of the ERT is based on the method described by Miller and McPherson as computed by the time required to reduce the concentration of a conservative constituent to some percent of its original concentration. For the analysis, an initial dye concentration was set to 100 units within the system, with all boundary conditions set to zero, and the models run until the dye concentration was less than 1 percent of the original value (a value of 10 percent remaining is usually used to estimate the ERT). The ERT was also evaluated using water age, a state variable in EFDC. Low and high hydrologic conditions were estimated for the inflows of the system using the information developed by previous studies to evaluate the response of the system. Results suggest that the estuary is characterized by a relatively low ERT and demonstrated that the use of a hydrodynamic model as EFDC is an effective means to evaluate the ERT in an estuary.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Ramirez-Avila J.J., Ortega-Achury S.L., Sotomayor-Ramirez D.R., Martinez-Rdoriguez G.A., Mas E.G.

A vegetated filter strip (VFS) is intended to remove pollutants from runoff flowing through it as sheet flow. VFS can be effective in reducing sediments and associated pollutants such as hydrocarbons, metals and nutrients through sedimentation and filtration. Soluble pollutants may also be removed through uptake by vegetation. In a properly designed VFS, water flows evenly through the strip, slowing the runoff velocity and allowing contaminants to settle from the water. In addition, where VFS are established, fertilizers and herbicides no longer need to be applied right next to susceptible water sources. Vegetative filter strips also increase wildlife habitat. This study evaluated the relationship between VFS width and trapping efficiency for sediment, phosphorus and nitrogen and to produce a design aid for use where specific water quality targets must be met. Runoff collection devices were placed at 0, 10 and 20 m within a grassed VFS established at the outlet of two dairy farm fields in Puerto Rico, which received periodic application of inorganic and dairy sludge irrigated amendments. Collected runoff samples were analyzed for suspended solids (SS), dissolved phosphorus (DP), total phosphorus (TP) and total Kjeldahl nitrogen (TKN) concentrations. Nutrients concentrations high above environmental targets were observed in runoff events that occurred within 10 days after organic amendment irrigation. Runoff DP and TP concentrations were significantly reduced, while an important but not significant reduction in runoff TKN concentration was observed at the wider VFS. Results showed that SS concentrations in runoff were not significantly reduced because the entering concentrations were minimal. The 20-m VFS wide was effective to reduce runoff nutrient concentrations below target levels; however other best management practices (BMPs) such reducing application volumes but increasing frequency of application and by spreading and/or irrigating the amendments on dates when significant precipitation events are less expected, are needed to reduce the potential impact of nutrient losses on water quality of waterbodies.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Byrd C.B.

Over the last ten to twenty years, most of the streams in the interior of the Mississippi Delta have lost most, if not all, of their base flow from the shallow aquifer that is used for irrigation and fish culture. There are several reasons for this situation, some of which date all the way back to the early 1900s and perhaps even as far back as the mid 1800s.

Shortly after Mississippi became the nation’s 20th state in 1817, settlers began coming to the Delta area to try to establish a new life for themselves and their families. They found vast swamps and thick, thick forests. Most of these first pioneers arrived between 1825 and 1827 and brought with them the means of making a living they had known all their lives—cotton farming. But before they could farm, they had to clear the land. Then once the land was cleared, drainage was a tremendous problem. As far back as the early 1900s, farmers banded together to form drainage districts. Within these drainage districts, they voluntarily taxed themselves so that drainage ditches could be dug to take excess water more quickly to the nearest Delta streams.

Approximately 9.2 million acres of forest in the Lower MS Valley had been removed. And even by the 1960’s, areas that were frequently flooded, but were mostly undisturbed, were converted from forests to fields as a result of federal agencies’ flood control projects. As virgin forests disappeared, farmland increased. For many, many years cotton was considered the King of all the crops grown in the Delta. In 1950 soybeans and rice began to be grown. Then in the early 1960s catfish farming developed as an important source of income.

With more land dedicated to crops other than cotton, especially rice and catfish, irrigation from groundwater became extremely important. The volume of water pumped from the shallow aquifer known as the Mississippi River valley alluvial aquifer, or MRVA, has increased significantly from approximately million gallons per day annually in 1954 to a current estimate of perhaps as much as 1.5 billion gallons of water per day.

Along with the increased usage of the MRVA, there has been a decrease in the water level in this aquifer. So much so that at least for the northern half of the Delta, the water level has fallen below the channel bottoms of the interior streams—thus causing baseflow from the aquifer to those streams to either be reduced significantly or to totally disappear.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Costanza K.E.

Flash flooding is a serious threat that accounts for the largest number of weather related deaths per year in the United States. The National Weather Service realized the severity of this threat during the Independence Day flooding event of 1969 which killed 41 people over a few counties in Ohio. That event sparked the National Weather Service to begin issuing some form of flash flood guidance that could effectively warn communities of potential flash flooding risks associated with a rain event. Over the years, the models for determining the flash flood guidance values have evolved from simple "rules of thumb" to a more scientific basis.

The current model, the Gridded Flash Flood Model (GFFG), used to determine flash flood guidance is based on a 4km by 4km grid scale and uses the National Resources Conservation Service (NRCS) Curve Number methodology. This method was chosen because of its ability to take into account the antecedent soil moisture conditions of a system, calculate the abstractive losses based on a Curve number, and calculate a peak flow by way of the Triangular Unit Hydrograph method. The determination of the antecedent soil moisture conditions are determined by a distributed hydrological model and relayed to the GFFG Model. The NRCS Curve Number method is also appealing because it can be tied to the physical world through the determination of a curve number which can take into account the spatial variability of soils types, vegetative cover and slope of a watershed. The final guidance of the model is varying rainfall amounts associated with the appropriate temporal scales (1, 3, 6, 12 and 24 hour) likely to cause flooding for an area.

Due to the serious nature of flash flooding, the need for improvement to the current model is imperative. Although the current model is a drastic improvement relative to the past models, there is still room for further improvement. One example would be incorporating finer spatial resolution data, such as soil data, to determine new Curve Numbers used in the model. With current GIS applications, the incorporation of this type of data is relatively simple. Other more advanced improvements could include evaluating different infiltration models to determine the abstractive losses of the system. The methods used in the current model are strictly empirical and the use of more physically based infiltration models could produce better results. In addition, the current model lacks connectivity between grid cells which could cause issue if there is a rain event upstream of a "problem cell". This connectivity could be gained by routing flow from one cell to another. Continued scrutiny of the current model will only yield improved guidance issued to communities resulting in more credibility of products rendered by the National Weather Service.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Stokes C.E., Prewitt M.L., Borazjani H.

Pentachlorophenol (PCP), a highly toxic and recalcitrant wood preservative, contaminates groundwater aquifers in many areas of the United States. Improper handling, storage, and disposal practices in the past have led to the contamination of groundwater at many wood treatment facilities. Air sparging, the injection of clean air under pressure into the groundwater system, has emerged as a viable in-situ treatment option for removal of this type of contamination. Previous studies have relied on morphological studies for identification of the bacterial community that is responsible for PCP degradation. However, molecular identification of DNA extracted from the bacterial community present in the groundwater will provide a more accurate description of the microbial community. Groundwater samples from eight biosparging wells were taken quarterly and analyzed for total PCP concentration, nutrient content, and monthly samples were used for microbial identification. Microbial counts were taken for each well on selective media, and changes over time were compared between wells within the sparging wells’ zone of influence and wells not directly impacted by air sparging. PCP concentration was below 1 ppb and nutrient levels were within the normal range. Well 14 (above air injection) revealed Burkholderia sp., Denitratisoma oestradiolicum, Thauera sp., and Rhodoanobacter thiooxydans, along with >40 other species that were listed as "e;uncultured" in BLAST. Well 51 (below air injection), presented a greater variety of bacterial species than Well 14, including the known PCP degrader Flavobacterium, in addition to numerous "uncultured" species. DNA extracted from other wells is currently being sequenced and T-RFLP analysis is underway to provide a comparison over time of microbial communities between aerated and non aerated wells.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Chakravarty P., Cizdziel J.

Mercury, a non essential element with a complex biogeochemical cycle, has emerged as a serious public health concern in Mississippi. Fish consumption advisories were issued for the Enid Reservoir in May 1995 and Yocona River in September 1996. The origin of Hg in these water bodies is unclear but may include atmospheric deposition, geological formations that leach Hg into the watershed, and historic land use practices. The atmosphere is recognized as an important source of trace metals to aquatic ecosystems through wet and dry deposition. Sediments constitute an important storage compartment for the inorganic forms of mercury that are precursors of the toxic and bioaccumulatable methylated form generated primarily by sulfate-reducing bacteria. In sediments, mercury is normally present at low concentrations typically ranging from 0.003–4.6 mg/kg. In this study, intervals of sediment cores from wetlands in northern Mississippi were analyzed for total mercury using a direct mercury analyzer based on combustion, amalgamation with gold, and atomic absorption spectrometry. The goal is to determine the extent of mercury contamination in the wetlands and search for temporal and spatial patterns of mercury deposition. This poster will discuss the technology and presents results for the various samples.

Final Project Report, Project #2009MS87B

Year: 2010 Authors: Prewitt M.L., Borazjani H., Diehl S.V.

Pentachlorophenol (PCP) is a toxic and recalcitrant compound used predominately as a wood preservative to protect wood from decay caused by insects and microorganisms. Past storage, treatment and disposal practices of PCP have resulted in groundwater contamination near wood treating sites in Mississippi and nationwide. Because of PCP’s recalcitrant nature and toxicity, it has been listed as a priority pollutant by the Environmental Protection Agency. Methods to remediate PCP in groundwater include pump and treat, filtration, and biosparging. Of these methods biosparging is the only in-situ method which substantially should reduce the remediation costs. Biosparging forces clean air under the groundwater table stimulating the indigenous microorganisms to degrade the pollutant. In this study eight biosparging wells were installed at a wood treating site in central Mississippi with contaminated groundwater. Two wells (#14 and #44) were located above and 6 wells (#42, #52, #43, #51, #41 and #17) were located beneath the air sparging lines. Water samples were collected quarterly for nutrient analysis, PCP concentration and microbial identification. In addition water samples were also collected monthly before and after nutrient amendment for microbial enumerations. Nutrients added were nitrogen, phosphorus, and potassium. After nutrient addition the largest increase in nutrient levels occurred for nitrogen and ortho-phosphorus in well numbers 52 and 17 both located near and far respectfully below the air sparging lines. Wells 52 and 17 also showed greater changes in Total Organic Phosphorus (TOP), Total Organic Carbon (TOC) and chloride ion (Cl^-) over time than the other wells. Total bacteria and PCP tolerant bacteria were highest in well # 14 located slightly above the sparge lines after eight monthly nutrient additions. PCP concentrations varied during the sampling period but did not decrease. Identification of PCP tolerant bacteria based on molecular methods revealed 17 bacterial species of which two were known PCP degraders, Burkholderia cepacia and Flavobacterium sp.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Roth K.

The Lower Mississippi River Forecast Center (LMRFC) uses the National Weather Service River Forecast System (NWSRFS). This system includes a variety of hydraulic and hydrologic techniques and operations that handle everything from the initial processing of historical data to the preparation of river forecasts. At the time of development (1971) NWSRFS was run on a mainframe computer and the code was streamlined to function with the limited computer resources of the day. Computer hardware and software development architecture have advanced in the last 40 years so that much of the NWSRFS functionality is no longer necessary. NWSRFS requires a large amount of maintenance and is no longer cost effective to keep it in service.

In 1997, the Office of Hydrologic Development (OHD) and a team of hydrologists began the process of investigating solutions for the aging NWSRFS. After much research and testing of software, FEWS (Flood Early Warning System), developed and maintained by the Dutch Company, Deltares, was chosen as the replacement for NWSRFS. The FEWS software is platform independent and offers a service oriented architecture that is modular in a sense like NWSRFS, but lent itself to more readily incorporating new modules and techniques. The FEWS software communicates with the hydrologic/hydraulic models and modules using a standard XML based protocol for which an adapter can be developed to pass information to and from and execute. To make it usable for the River Forecast Centers, FEWS adapters were developed to use many of the existing hydrologic operations, techniques, and models from NWSRFS. The Community Hydrologic Prediction System (CHPS) became the NWS’s customized application of FEWS. CHPS runs models that are compatible with FEWS including those migrated from NWSRFS.

Currently CHPS is installed at the LMRFC but is not fully operational. To make it operational, the staff is migrating all of the hydrologic data necessary, to make a forecast, from NWSRFS to CHPS. This process is largely done automatically by scripts but some local customization is necessary. Once the migration to CHPS is complete and the model is running and stable, the LMRFC will begin parallel operations where we will produce forecasts using NWSRFS and CHPS. These forecasts will then be compared to verify that similar results are being achieved. After a period of evaluation, NWSRFS will be retired and CHPS will be the operational forecast system used at the LMRFC.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Moran M., Young A., Diaz-Ramirez J.

The Mississippi Delta region is filled with fertile farmland formed from rich sediment deposits of the Mississippi River. The Big Sunflower Watershed comprises a large majority (221,270 acres) of the fertile Mississippi Delta region. Approximately 75% of the Big Sunflower Watershed is used for agricultural purposes. The heavy agricultural activity increases the impairment of water bodies due to excess nutrient loads. The excess nutrient loads increases the occurrence of hypoxia and harmful algal blooms. Best Management Practices (BMPs) are a cost-effective way of reducing the non-point source nutrient loads in water bodies. Hydrologic models are to be used to estimate nutrient loads under existing conditions, then estimate the conditions following the implementation of Best Management Practices. Through the use of Better Assessment Science Integrating point & Nonpoint Sources (BASINS) and Hydrological Simulation Program—FORTRAN (HSPF) the nutrient loads in the Big Sunflower Watershed can be effectively modeled. Better Assessment Science Integrating point & Nonpoint Sources (BASINS) is a multi-purpose environmental analysis system that integrates a geographical information system (GIS), national watershed data, and environmental assessment tools into one package. Built into BASINS is the Hydrological Simulation Program—FORTRAN. HSPF simulates the hydrologic and associated water quality processes on pervious and impervious land surfaces and in streams and well-mixed water bodies [USGS]. These tools will be used to conduct a nutrient management study on three sub watersheds within the Big Sunflower Watershed (two sub watersheds of Porters Bayou and one of Harris Bayou). After applying the hydrologic models to the existing conditions, the models will be used to predict nutrient loads after the implementation of BMPs. The Best Management Practices being used are input management, edge of field practices, and constructed wetlands. The nutrient study on these areas will test and validate the hydrologic tools, BASINS/HSPF, for nutrient load predictions in watersheds.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Welch H.L., Kingsbury J.A., Coupe R.H.

Previous localized studies of groundwater samples from the Mississippi River Valley alluvial (MRVA) aquifer have demonstrated that dissolved phosphorus concentrations in the aquifer are much higher than the national background concentration of 0.03 milligram per liter (mg/L) found in 400 shallow wells across the country. Forty-six wells screened in the MRVA aquifer in northwestern Mississippi were sampled from June to October 2010 to characterize the occurrence of phosphorus in the aquifer, as well as the factors that might contribute to high dissolved phosphorus concentrations in groundwater. Dissolved phosphorus concentrations ranged from 0.12 to 1.2 mg/L with a median concentration of 0.62 mg/L. The predominant subunit of the MRVA aquifer in northwestern Mississippi is the Holocene alluvium in which median dissolved phosphorus concentrations were higher than the Pleistocene valley trains deposits subunit. Highest phosphorus concentrations occurred in water from wells located along the Mississippi River. A general association between elevated phosphorus concentrations and dissolved iron concentrations suggests that reducing conditions that mobilize iron in the MRVA aquifer also might facilitate transport of phosphorus. Using baseflow separation to estimate the contribution of baseflow to total streamflow, the estimated contribution to the total phosphorus load associated with baseflow at the Tensas River at Tendal, LA, and at the Bogue Phalia near Leland, MS, was 23 percent and 8 percent, respectively. This analysis indicates that elevated concentrations of dissolved phosphorus in the MRVA aquifer could be a possible source of phosphorus to streams during baseflow conditions. However, the fate of phosphorus in groundwater discharge and irrigation return flow to streams is not well understood.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: McAnally W.H., Martin J.L., Alarcon V., Diaz-Ramirez J., Amburn P.

Oil spilled from the Deepwater Horizon incident has been reported washing ashore from Florida to Texas, affecting shoreline over thousands of km. Beyond the effects of the oil itself are those of the dispersants that have been used and the combined oil-dispersant emulsions. BP, Inc. has asked the Northern Gulf Institute (NGI) to provide research results that will, among other objectives, predict the distribution, dispersion and dilution of these contaminants under the action of currents and storms in estuaries. In response, an integrated assessment of physical and biological processes and effects of oil spills in the Gulf of Mexico is being performed by an interdisciplinary NGI team. This paper reports on the use of numerical models to examine the transport and fate of those contaminants in nearshore waters.

The use of mathematical models is well established, such as in the regulatory environment to estimate impacts of remediation of contaminated sediments and a variety of other purposes. Predictive water quality models are typically used to develop linkages between sources and targets. The models provide a quantitative link between sources and targets, or cause-and effect relationship, in order to determine the capacity of the waterbody to assimilate contamination and to address the site-specific nature of the problem. Models of open waters and Gulf estuaries most commonly include hydrodynamic, sediment, and water quality models, due to the importance of transport on the fate of water quality constituents. The models may then be focused on the kinetic and transformation process impacting the specific issue of concern (oil spills, etc.) in order to address specific concerns such as algal growth, hypoxia, and others.

The research is focusing on quickly applying available models of Gulf estuaries, demonstrating how they may be used to assess the long-term impacts of the oil spill (e.g. on hypoxia, sequestration in sediments, toxicity to algae, etc.), establishing and prioritizing remedial actions, and indentifying deficiencies in the literature impacting or introducing uncertainty into those predictions, such as kinetic rates impacting fate. Visualization and interpretation of the results is a key component of the assessment, so 2D and 3D visualization tools have been employed.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Dornback M., Lohrenz S.

This study is observing the temporal and spatial fluctuations in phytoplankton biomass in the water column in relation to light availability, nutrients, and environmental factors such as salinity and temperature. The focus will be on what factors promote changes in phytoplankton biomass above and below the stratified layer and in a mixed water column. This is particularly important because harmful algal blooms and summertime hypoxia are both linked to water column stratification.

Monthly cruises (9/07-Present) are conducted to collect the samples. Optical instruments are used to measure in situ light absorption (ac-9), attenuation (ac-9), and backscatter (bb-9) in nine different wavelengths. Phytoplankton biomass is measured through the proxy of in situ chlorophyll a (chl a) fluorescence intensity using a FL-3. A CTD is used for measurements of salinity (converted from conductivity), temperature, and depth.

Water samples from the start, middle and end of the transect are collected at multiple depths and returned to the lab for analysis of nutrients (N, P, Si), chromophoric dissolved organic matter absorption, the pigmented and non-pigmented absorption fractions of suspended particulate matter and the bulk mass of the suspended particulate matter.

The western Mississippi Sound is a vital economic and ecological resource to the surrounding region. A large percentage of coastal residents between Bay St. Louis and Biloxi and rely on the Sound for revenue from tourism and fisheries. The water quality of fishery habitats and nurseries can greatly affect fauna health and the health of human consumers. It is important for coastal water quality to be properly assessed in order to understand the threats to the local ecosystem and to mitigate any anthropogenic causes.

Preliminary results show fluctuations in chlorophyll a abundance through the months and between sampling stations on a single month. Distinct phytoplankton blooms are detected above and below the pycnocline. More analysis of the water column properties will need to be conducted to understand the reason between the fluctuations.

In addition, major environmental disturbances such as hurricanes (Gustav 9/1/08-9/2/08, Ida 11/9/09-11/10/09) and the Bonnet Carre Spillway opening (4/11/08-5/12/08) have been detected in the monthly optical profiles. Further analysis of the data will have to be conducted to see if any anomalies are detected due to the Deepwater Horizon oil spill.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Hicks M., Stocks S., Wright J.

A multi-agency task force forum, The State Nutrient Strategy Work Group, was formed in 2009 for the purpose of developing a consistent approach among Mississippi/Atchafalaya River Basin states to reduce nutrient loadings from streams and rivers draining into the Gulf of Mexico. As part of this forum, a nutrient reduction strategy for the Delta region in northwestern Mississippi was developed. One of twelve critical elements identified in the nutrient reduction strategy was to implement "Monitoring Programs" for the purpose of documenting nutrient concentration and load reductions, lag times, and watershed system responses. To address this element, two project areas were identified: Harris Bayou watershed, Coahoma County, MS, and Porter Bayou watershed, Sunflower County, MS. Project areas were chosen based on areas where there has been historically high nutrient concentrations and where land-owners are willing to participate in this effort. These two watersheds are also located in a focus area watershed of the Mississippi River Basin Initiative. Efforts have begun to implement various Best Management Practices (BMPs) in four catchments, two in each of Harris and Porter Bayous, for the purpose of improving water quality by reducing nutrient loading to streams affecting downstream aquatic ecosystems. In 2010, the U.S. Geological Survey, in cooperation with Mississippi Department of Environmental Quality, U.S. Army Corps of Engineers, and Delta Farmers Advocating Resource Management (F.A.R.M.) began implementation of a monitoring strategy at two stations in Porter Bayou watershed and four stations in Harris Bayou watershed. The strategy involves monitoring before and after BMPs have been implemented, as well as using a paired basin approach for data analysis of changes due to the BMP project. Data collection activities at each site include base and storm flow sampling for flow, total nitrogen and other nitrogen species, total phosphorus, suspended sediment, and other physical and chemical water quality indicators of ecosystem health, including response indicators such as benthic macroinvertebrate community assemblages and chlorophyll-a concentrations.

Proceedings of the 40th Mississippi Water Resources Conference

Year: 2010 Authors: .

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Rose C.E., Detavernier A.C., Coupe R.H.

End-member mixing analyses use chemical signatures of water sources to determine the contribution of each source to a stream. Low flow in the Bogue Phalia, a river in northwestern Mississippi, during the summer season is typically from two primary sources; (1) baseflow from shallow groundwater and bank storage, and (2) irrigation return flow. Irrigation return flow originates from the Mississippi River Valley alluvial aquifer’s deep irrigation wells. This water has sometimes been shown to have dissolved phosphorus concentrations (0.01 to 1.0 mg/L), and sometimes have exceeded the USEPA surface water criteria. There is concern that irrigation return flow might be adversely affecting the quality of the surface water. The chemical signature of the shallow groundwater was determined from water samples collected from the Bogue Phalia in the fall, during baseflow. Water samples from the alluvial aquifer were used to determine the chemical signature of the irrigation return flow. These two water sources have distinctly different specific conductance values; this enabled the determination of the contribution of water from both sources to the Bogue Phalia during the irrigation season, when the influence of rainfall or other water sources would be minimal. An end-member mixing analysis was used to estimate of the percentage of both water sources. From this method, which consisted of the use of a numerical formula, discharge and continuous specific conductance data from the Bogue Phalia from 2001 to 2008, the influence on the in-stream concentration of phosphorus from irrigation return flow can be determined.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Ramirez-Avila J.J., Langendoen E.J., McAnally W.H., Ortega-Achury S.L., Martin J.L.

A combination of in situ monitoring and characterizing methods were performed on different locations along the principal channel of the Town Creek in Northeastern Mississippi to quantify the contributions of streambanks to stream sediment loads and better understand the processes of streambank erosion. Results and field observations demonstrate that streambank instability is widespread and the highly erodibility of the streambank materials made streambanks important potential sources of sediment along the entire watershed. Streambanks predominantly lost materials through gravitational failures and removal of sediments by hydraulic forces along the watershed headwaters, commonly represented as incised channels near agricultural areas. Headwaters would represent up to 70% of the total sediment load exported from the entire watershed. Changes in channel morphology, vegetation and streamflow patterns favored the significant amount of sediment deposition amounts observed along the middle area of the watershed. Reduction of suspended sediment loads should focus on the attenuation of geomorphic processes and stabilization of reaches and agricultural lands near streambanks at the headwaters within the Town Creek watershed. Observed results and modeling process offer important insights into the relative effects of land and streambank erosion on the sediment budget for Town Creek watershed, on stream water quality and how management measures can effect improvements.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Wax C.L., Pote J.W., Thornton R.F.

The shallow alluvial aquifer in the Mississippi Delta region is heavily used for irrigation of corn, soybeans, and cotton, as well as for rice flooding and filling aquaculture ponds in the prominent catfish industry. Water volume in the aquifer is subject to seasonal declines and annual fluctuations caused by both climatological and crop water use variations from year-to-year.

Available climate, crop acreage, irrigation water use, and groundwater decline data from the 19 counties in the Delta were used to construct a model that simulates the effects of climatic variability, crop acreage changes, and specific irrigation methods on consequent variations in the water volume in the aquifer. Climatic variability was accounted for by predictive equations that related annual measured plant water use (irrigation) to total growing season precipitation amounts. This derived relationship allowed the application of a long-term climatological record (50 years) to simulate the cumulative impact of climate on groundwater use for irrigation.

The relationship between rainfall and anticipated crop water use was initially estimated by a simple regression between total growing season rainfall and measured irrigation water use for the period 2002-2007, with a resulting R² value of 0.93. Adding data from 2008 caused R² to drop to 0.63. It was recognized that total growing season rainfall was not representative of the timing, or episodic nature, of rainfall compared to plant water demand day-by-day through the growing season. To account for this timing issue, weekly rainfall amounts were compared to weekly expected crop water demand to produce an effective rainfall estimate. The resulting improvements are shown. This effective rainfall compared to irrigation use is expected to provide a much-improved rainfall-irrigation coefficient for use in the model.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Clifton N.

The Mobile Bay watershed covers two thirds of the state of Alabama and portions of Mississippi, Georgia, and Tennessee. It is the fourth largest watershed in the United States in terms of flow volume and is the sixth largest river system in the U.S. in terms of area. The lower Mobile Bay is a designated national estuary under the EPA’s National Estuary Program. The Mobile Bay and the rivers draining into it support major uses with national implications which include the Tennessee-Tombigbee Waterway, the Port of Alabama, various commercial fisheries, large industry, tourism and recreation, and abundant development. Water in the upper-most reaches of the watershed makes its way to the Gulf of Mexico through Mobile Bay. Throughout this process sediments and nutrients are transported and deposited along the way. It is important to understand the mechanisms and processes of how sediments move through the entire watershed to aid in making informed management decisions relating to sedimentation, water quality, environmental resources, habitat management, and human uses.

One of the primary tasks of the Mobile Basin Regional Sediment Management project is to develop a Regional (Watershed) Sediment Management Plan to provide the necessary elements for the management of sediment resources while considering environmental restoration, conservation, and preservation. The plan is intended to also maximize interagency collaboration to assess current management practices towards improving water quality and optimize beneficial use of sediment resources. The management plan will:

• Develop understanding of system dynamics and provide for better management of resources in the region including sources, movement, sinks, related watershed and coastal processes, and influences of structures and actions that affect sediment movement, use, and loss
• Provide guidelines and recommendations towards a holistic watershed management approach
• Encourage more effective management of watershed resources, recognizing they are a part of a regional system involving natural processes and man-made activities.
• Develop technical framework that provides the foundation associated with holistic watershed processes
• Provide understanding of regional sediment systems and processes
• Facilitate cooperation among stakeholders to enhance abilities to make informed cooperative management decisions and develop regional strategies across jurisdictional boundaries.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Martin C.L., Milroy S.P.

While several studies on chromophoric dissolved organic material (CDOM) have been conducted in a variety of coastal regions throughout the world, only a handful have focused in the area of the northern Gulf of Mexico (Bissett et al, 1999, Chen et al, 2004, Ohlmann et al, 2005, Zanardi-Lamardo et al, 2004). Fed by the Mississippi River plume to the southwest as well as Pearl River, Biloxi Bay, Pascagoula River, and Mobile Bay effluents, the Mississippi Sound represents a dynamic and under-explored area for the study of nearshore CDOM and the correlated watersheds. Over a series of cruises conducted from 01 APR– 30 JUL 2010, a spectrophotometric determination of surface CDOM was enjoined using comparative filtration and centrifugation methods. Ultimately, a simple algorithm of the CDOM absorption coefficient a_cdom(λ) was developed to help resource managers and Marine GIS professionals characterize the optical properties of nearshore waters within the MS Sound using simple salinity measures as a means to estimate a_cdom(λ) using visible and near-IR spectra.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Hicks M., Stocks S.

The Mill Creek watershed in Rankin County, Mississippi, drains 6,200 acres and flows into Pelahatchie Bay of the Ross Barnett Reservoir. In the last twenty years, the watershed has experienced a large amount of urban growth and development. As a result of this landscape change, non-point source pollution concerns to the health of Mill Creek, its tributaries, and Pelahatchie Bay have emerged. A locally led watershed implementation team developed a plan that identified primary pollutants to Mill Creek watershed and outlined restoration activities necessary to restore the watershed to healthy conditions. Erosion and increased sedimentation were identified as primary and immediate concerns to the health of Mill Creek watershed and to the health and fisheries of Pelahatchie Bay. Strategies implemented to address sediment loading to Mill Creek included a range of activities such as bank stabilization, flow control structures, slope drains, ditch stabilizations, check dams, and storm-water runoff compliance and enforcement actions. Beginning in 2006, the U.S. Geological Survey, in cooperation with Rankin County Board of Supervisors and Mississippi Department of Environmental Quality, began collecting water quality and streamflow data at six fixed stations in the watershed. The purpose of data collection was to document changes in suspended sediment concentrations and loads in Mill Creek and its tributaries before and after watershed restoration activities were implemented. Monitoring included the collection of stream flow, suspended-sediment concentration, and precipitation data. Preliminary data analysis suggests a decrease in sediment concentrations and loads, which may be attributable to watershed restoration activities.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Wilson K.V., Turnipseed D.P., Thatcher C., Sempier S., Wilson S.A., Mason Jr. R.R., Marcy D., Burkett V.R.

Coastal communities throughout the U.S. are in the initial stages of thinking about, planning, and/or creating climate adaptation plans. Emergency managers, developers, and the general public need to know the potential impact of a rising sea level and how that phenomenon may influence plans for developing future critical infrastructure and for habitat restoration and conservation.

In late 2008, in response to these critical needs, the U.S. Geological Survey and the National Oceanic and Atmospheric Administration in concert with the Mississippi-Alabama Sea Grant Consortium, the Delaware Department of Natural Resources and Environmental Control and several other Federal, State, and local stakeholders formed a team to create two pilot internet map applications that could effectively project various sea level rise scenarios on the Alabama-Mississippi Gulf of Mexico Coast and the mouth of the Christina River and Upper Delaware Bay at Wilmington, Delaware.

The Alabama-Mississippi Gulf of Mexico Coastal pilot Internet Map Server (http://gom.usgs.gov/slr/index.html) was developed from an existing server which was built principally to display the maximum storm tide crest resulting from Hurricane Katrina (2005). This server quickly and easily projects 1-, 3-, and 6-ft sea level rises onto a 3-meter digital elevation model constructed from Light Detection and Ranging (LiDAR) data procured before Hurricane Katrina.

The Delaware River pilot (http://csc-s-web-q.csc.noaa.gov/de_slr/index.html), developed with a similar concept, used a 2-meter horizontal Digital Elevation Model created from State of Delaware LiDAR data to illustrate a hypothetical 4 ft. rise in sea level. Flood frequency estimates were computed based on National Weather Service coastal flood warning criteria to show how these increases in sea level could make daily tidal flooding worse.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Hatten J., Dewey J., Mangum C., Choi B., Brasher D.

The discharge of particulate organic carbon (POC) and particulate nitrogen (PN) from watersheds can be important in terms of carbon and nitrogen cycling and can also carry information about the process of erosion and sediment transport within the watershed. This paper will address the transport processes of POC, PN, and total suspended solids (TSS) during high discharge events in four ephemeral streams and a perennial stream of a small managed-forest. For this study, a 30 ha watershed located approximately 8 miles west of Eupora in Webster County, MS was monitored for water discharge, TSS, POC, and PN. These constituents were measured in 4 ephemeral streams and in one downstream perennial stream location. We assessed the %POC, %PN, and C/N of TSS across a range of discharges during large storm events. Preliminary results suggest that %POC and %PN may have an inverse relationship with TSS and discharge in all watersheds at all scales. The relationship between %POC, %PN, and C/N and discharge and TSS appeared to be different between the ephemeral and perennial streams suggesting that the process of sediment transport are different at each scale. These results point toward a need for a better understanding of sediment transport in managed watersheds and that the organic matter characteristics of TSS can play a strong role in this understanding.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Kroger R., Neal J.W., Munoz M.

Water quality of reservoirs is the foundation of the ecological cascade that results in productive fisheries. The current study evaluated four tropical reservoirs (Dos Bocas, Cerrillos, Guajataca, and Lucchetti) in Puerto Rico for spatial and temporal dynamics in water quality parameters to better understand effects on bait fish and subsequently largemouth bass sport fisheries. Surface mapping, and depth profiles of in situ parameters of dissolved oxygen, pH, temperature and turbidity using an automated flow through Eureka Manta data-son yielded distinct differences between reservoirs in space and time. Several limnological phenomenon were observed within this dataset including distinct influence of river inputs into reservoirs, the prevalence of irradiance avoidance, and substantial and significant oxyclines with depth at varying times of the year. These spatial variations in water quality variables result in direct implications for resource availability. Nutrient concentration ranges were significantly different between reservoirs (F = 6.45; P < 0.05) and were attributed to varying degrees of land use in the respective upland catchments (Dos Bocas NO3-N: 0.8 mg/L; Guajataca NO₃-N: 0.04 mg/L). Nutrient concentrations were low in all reservoirs, with certain reservoirs (Cerrillos and Guajataca) being classified as oligotrophic. Although no direct correlations can be made to fish production, it is important to understand limits to resource production within these systems. Dissolved oxygen, pH, water temperature and nutrient concentrations all work in unison to provide a bottom-up controlled aquatic system that sustains phytoplankton production, baitfish and subsequently sports fisheries.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Parajuli P.

Sediment and nutrients loading from the non-point sources of agricultural and non-agricultural activities contribute to water quality degradation. Developing sediment and nutrients Total Maximum Daily Loads require quantifying pollutant load contribution from each potential source. The determination of pollutants reduction strategies from each source is required to meet applicable water quality standards. The watershed-scale evaluation of the effects of the agricultural, and pasture management practices on water quality can be estimated using watershed water quality models.

The objective of this research was to evaluate spatially distributed sediment and nutrients loading from the Upper Pearl River watershed (UPRW-7,885 km²) in east-central Mississippi using modeling approach. Nutrient sources from agricultural and non-agricultural activities of the UPRW were analyzed and model inputs were developed. The Soil and Water Assessment Tool model was calibrated, and validated in the UPRW to evaluate sediment, and nutrients loading. The model results were evaluated against monthly observed water quality values using coefficient of determination (R²), and Nash-Sutcliffe Efficiency Index (E).

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Nica C., Cho H.J.

Submerged aquatic vegetation (SAV), a unique group of flowering plants that have adapted to live fully underwater, is a valuable resource and indicator of aquatic habitat quality. Coastal SAV beds perform a number of irreplaceable ecological functions in chemical cycling and physical modification of the water column and sediments. They also provide food and shelter for commercial, recreational, and ecologically important organisms. The cumulative effects of alteration of natural habitats and decline in coastal environmental quality are causing a decline of coastal SAV. In Mississippi Sound, seagrass beds have reportedly declined >50% since the 1969 Hurricane Camille. In addition, the more significant declines occurred in stable, climax community seagrasses such as Turtlegrass (Thalassia testudinum K.D. Koenig) and Manateegrass (Syringodium filiforme Kutzing), which have resulted in the increased relative abundance of opportunistic, pioneer species such as Wigeongrass (Ruppia maritime L.) and Shoalgrass (Halodule wrightii Aschers) in estuaries and along barrier islands of the northern Gulf of Mexico. Temporal changes in their distribution and abundance indirectly reflect changes in the habitat quality and environmental health status. In this study we are presenting data on seagrass community dynamics by following patterns of biomass allocation at three sites at Grand Bay National Estuarine Research Reserve (NERR), Mississippi. Other pertinent water quality parameters—turbidity, [chlorophyll a], dissolved color, dissolved oxygen, pH, salinity, temperature, sediment, nutrients, and water level were monitored or obtained from the NERR monitoring data. Total biomass and root to shoot ratio were significantly different among the sites, with species composition (R. maritime dominant or Ruppia-Halodule mixed beds) being the most important explanatory variable. The general seasonal pattern showed that the biomass began to increase in April, and peaked in May-June, then decreased in September as Rupppia senesces. Our results suggest that fresh water regime due to precipitation and predominant wind direction might be one of the environmental factors contributing to the spatial difference.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Garner J.A., Cho H.J., Biber P.

Coastal submerged aquatic vegetation (SAV) abundance has declined globally due to the cumulative effects of habitat alteration and declines in coastal environment quality. There are several water quality/environmental models for seagrass/SAV habitat requirements; these models were developed based on long-term monitoring data. Application of those models by resource managers also requires extensive/consistent water quality monitoring data, hence, limiting their usages to the areas with well monitored habitats. It is necessary to develop habitat indices that can be widely used to predict SAV type/distribution in varying locations and habitat/basin types. In order to develop a Habitat Suitability Index (HSI) for SAV via a decision-tree algorithm approach that utilizes landscape properties, SAV communities of shallow waters in channels, adjoining bayous, streams, inlets, and lagoons of the Pascagoula River, Back Bay of Biloxi, St. Louis Bay, and Pearl River systems of coastal Mississippi were surveyed from May 2008 to Jun 2010. The location and species of SAV and the nearby floating aquatic and shore emergent plants were recorded. The survey extended from the river mouth to upstream areas where stream width became narrow and shade from tall trees on the shore restricted SAV growth. Survey methods included raking from a boat and wading in the water, after SAV were observed to occur in a given location. In addition to SAV species and bed location, dominant shore vegetation and GPS coordinates were recorded using a Trimble™ GeoXH handheld GPS unit and TerraSync™ software. After we develop a tree-based algorithm for the index, its validation will be assessed using a separate set of field data. Application of the index will not be restricted to the well-protected and monitored areas because the index will use geographic, topographic, and shore vegetation parameters. The resultant HSI can be used to visualize potential SAV bed locations and to predict how coastal landscape alteration would affect their distribution and abundance.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Stovall M.E.

The natural systems that make-up Mobile Bay, its watershed, and adjacent marine waters serve as critical natural infrastructure supporting water supply, transportation, power generation, recreation, commercial fishing, agriculture, forestry, and a wide variety of other valued uses for the people in the watershed. Development activities and multiple uses have placed signification stresses on the ecosystem and the sustainable use of its aquatic resources. These stresses have impacted the unique marine and freshwater biodiversity of this aquatic system.

This paper presents results of Phase 1 of a NOAA funded assessment of the freshwater and marine fisheries of the Mobile Bay watershed, the related aquatic system and the stresses placed on this system by both anthropologic and natural conditions The project is a collaborative effort among government, corporate, and private stakeholders to build the resource management decision support tools needed to assure a sustainable fisheries and coastal seafood industry for Mobile Bay and its watershed, while balancing statewide environmental, economic, and social demands.

Existing system conditions were initially characterized through review of available literature and agency documents. Two collaborative multi-stakeholder workshops were held in 2009 in order to gain their perspective on the most immediate threats to a sustainable Mobile Bay system. Challenges associated with multi-stakeholder coordination, resource allocation among potentially competing uses, and public education of how human activities potentially impact system health were ranked as higher threats for sustainable system management than more traditional environmental perturbations such as non-point source pollution or aging infrastructure.

Results from Phase 1 studies have identified tentative indicator species, sources of stresses, model boundary conditions and other major system components for Phase 2 activities to develop a preliminary decision support system, which will link riparian, stream, estuary, and near-shore marine conditions responses to various human use activities via selected indicator species monitoring. The long-term project outcome is to design and develop new tools to model and evaluate social and environmental factors that influence management of a sustainable fishery, support man-made infrastructure investment decisions, and provide a common language for expressing goals, processes, and concerns affecting responsible stewardship of Alabama’s fisheries resources.

Recent developments incorporating decision impacts of near-shore drilling will also be discussed.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Buck J., Orsi T.H., Rasmussen M., Newcomb A., Carter G.

There has been recent interest in improving the recreational value of the Chickasawhay River in Clarke County, MS, by removing large wood obstructions from the stream channel. The Pat Harrison Waterways District conducted an initial survey in 2002 and commissioned a follow-up in 2004, determining in both instances, that such a project would be extremely costly and ill-advised. None-the-less, the project proceeded from 2006-2008. Our purpose is not to speculate on whether the project was environmentally or financially appropriate, nor is it an attempted indictment of the agencies involved, past or present. Instead, we look to the historical record, seeking any information that might provide insight into the potential long-term success of a project like that conducted recently on the Chickasawhay.

Interestingly, "improvements" to the Chickasawhay River began over 100 years ago. Initial examination from Subuta to its confluence with the Leaf River began in 1878-1879 by the U.S. Army Corps of Engineers (USACE). This was followed a decade later (1888-1889) with an examination of the reach from Enterprise to Bucatunna. Both surveys concluded that the Chickasawhay was "badly obstructed by logs, snags, overhanging trees, shoals, etc." Regardless, the stream was considered "worthy of improvement by the United States" and a project began in 1890 to provide for high-stage navigation from Shubuta to the Leaf-Chickasawhay confluence.

Based on available Annual Reports to the Chief of Engineers, there are three general phases of USACE engagement with the Chickasawhay: (1) Improvement (1890-1900); (2) Maintenance (1900-1910); and (3) Depreciation (1910-1915). The Corps begins ambitiously in the 1890’s, removing or cutting up thousands of obstructions from the river as listed in an 1892 report:

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Wood M., Coupe R.H.

The Mississippi Alluvial Plain, an area lying within the Yazoo River basin in northwestern Mississippi, locally referred to as the Delta, is a relatively flat landscape where approximately 90 percent of the land is used for cultivation of corn, cotton, rice, soybeans, and catfish. Annually, the Yazoo River basin contributes around 1–3% of the nitrogen load to the Gulf of Mexico. Recent modeling studies suggest that that there is very little processing of nitrogen in the main channel and primary tributaries of the Yazoo River basin; nitrogen acts conservatively and does not undergo significant reduction through processes such as denitrification. The nitrogen loss rates used in these models are from other areas as there have been few studies on denitrification rates in the Delta. The Delta, which differs from the topography and climate of most of the rest of the United States, has slower stream velocities and higher temperatures than many areas of the United States; two key variables that control denitrification rates. If there is significant processing of nitrogen in the streams of the Yazoo River basin, this could have implications for managing nutrient reduction in streams and rivers of the Delta. During April–August 2010, four sets of samples were collected at ten sites located on the Big Sunflower River. Samples were analyzed for nitrate, nitrite, organic nitrogen, total nitrogen, chloride and sulfate. A Lagrangian procedure that followed the same parcel of water as it transited the Big Sunflower River was used to time the collection of the water samples. The objective of the study is to determine if nitrogen, once in the Big Sunflower River, is conservative in nature or undergoes significant loss.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Clary R.M., Brzuszek R.F., Wandersee J.H.

Previous researchers (Brzuszek et al 2009) investigated the role of non-governmental organizations (NGOs) in four northern Gulf Coast watersheds (Alabama, Florida, Louisiana, and Mississippi), and reported that the NGOs’ focus varied by watershed. However, subsequent analysis of these northern Gulf States’ educational standards revealed that the NGOs’ focus was not being reflected in the respective state’s water education requirements (Clary & Brzuszek 2009). Under the 2001 Mississippi Science Framework, 69% of the researchers’ 13 identified water topics were included, but most of these were non-required objectives, or within elective courses that are not taught at all Mississippi schools. Only one topic, pollution, was required to be taught as a state competency (grade 4). While Louisiana fared better than other coastal states with 54% of the water content topics in K-12 education, several topics were still omitted. Clary and Brzuszek (2009) concluded that greater collaboration was needed between watersheds, their associated NGOs, and educators to implement water education in public schools through the required science content standards.

However, science education is not static: Both the 2010-11 adoption of Mississippi’s 2010 Science Framework and the recently released 2010 National Research Council (NRC) draft of the conceptual Framework for Science Education indicate that new challenges and opportunities exist for water education. Our current research compared water education topics in the Mississippi 2010 Science Framework against the earlier 2001 Framework. While there is greater vertical alignment between grades K-8 in the 2010 Framework, many of the water topics are included as optional objectives and not as required competencies, resulting in increased water education possibilities with teacher flexibility. Content analysis of the preliminary public draft of the NRC science framework also revealed flexibility and water education potential: Although water education was not regularly mentioned in the document, the new NRC draft focuses upon "learning progression." Another notable change is the incorporation of Engineering and Technology as a fourth domain of science alongside the current domains (Life, Earth and Space, and Physical sciences).

Both Mississippi ’s vertical alignment and the NRC learning progressions are consistent with our best practices model (Clary & Brzuszek 2009). These documents also suggest a potential educational trend toward increased content reinforcement across grade levels and teacher flexibility. We suggest there may be increased opportunity for NGOs to develop water education programs at multiple grade levels that address these broader science standards, resulting in greater inclusion of water education within the local watershed.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Barrett J., Barefield A.

The Capacity Development Assessment (CDA) is a focused survey instrument used to quantify the financial, managerial and technical factors of a water system in Mississippi. The survey’s primary focus is identifying the extent to which water systems are complying with Mississippi State Department of Health-Bureau of Public Water Supply regulations and standards. Since the majority of the factors for publicly owned water systems (municipal systems and water associations and districts) measured in the CDA are either directly or indirectly influenced by board management decisions as well as other, more macro/regional external influences such as per capita income, water system population, county population, operator experience, etc., we propose to examine causal influences on the CDA score. Identification of these influences could lead to future local and state policy implementation and educational efforts to strengthen public water systems.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Brzuszek R.F.

The Sustainable Sites Initiative (SITES™) is a new national effort to create voluntary guidelines and benchmarks that promote sustainable land design and construction practices. Jointly sponsored by the American Society of Landscape Architects, the Lady Bird Johnson Wildflower Center, and the U.S. Botanic Garden; SITES™ provides a ranking system that awards points for comprehensive sustainable land practices for built projects. The program is complementary to LEED ® (Leadership in Energy and Environmental Design) Green Building Rating System, and it is anticipated that the SITES™ points will be incorporated into future versions of LEED ®.

SITES™ has five areas of focus—hydrology, soils, vegetation, materials, and human health and wellbeing. The program promotes examples of sustainable practices and awards up to 250 possible points for a project. A maximum of 44 possible points can be awarded for water practices. Credits are given for the following activities that protect and restore the processes and systems for a site’s hydrology:

• Reduce potable water use for landscape irrigation
• Protect and restore riparian, wetland, and shoreline buffers
• Rehabilitate lost streams, wetlands, and shorelines
• Manage stormwater on site
• Protect and enhance on-site water resources and receiving water quality
• Design rainwater/stormwater features to provide a landscape amenity
• Maintain water features to conserve water and other resources

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Milroy S.P., Moshogianis A.

Seasonal hypoxia is certainly common over the Louisiana-Texas (LATEX) shelf west of the Balize Delta, but over the last several years summer hypoxia has also been discovered east of the delta in the Mississippi Bight (Dillon et al. 2008, Brunner et al. 2009) and in the deeper reaches of the Mississippi Sound (Gundersen, pers. comm.). Hypoxia most commonly occurs during times of significant vertical stratification of the water column, caused by the complimentary effects of seasonal heating and freshwater discharge. These discharges, when laden with organic and inorganic nutrients, further exacerbate the geographic extent of these hypoxic water masses. While the causative agents of coastal hypoxia have been well-described, the synergies between coastal geomorphology and the net ecological burden (O₂ production v. respiration) within the Mississippi Sound/Bight are less well-known. Over a series of cruises conducted from 01 APR–30 JUL 2010, vertical profiles from thirty repeat stations within a highly resolved (25 km²) grid were analyzed monthly for in situ CDOM/phycoerythrin/chl-a fluorescence, temperature, salinity, and dissolved oxygen. Results indicate that differences between surface and near-bottom chl-a, coupled with the unique geomorphology of the Mississippi Sound/Bight, can produce hypoxic water masses with significant heterogeneity over fine spatial scales.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Kroger R., Brandt J.R., Fleming J.P., Huenemann T., Stubbs T., Prevost J.D., Littlejohn K.A., Pierce S.

The Wolf - Broad Lake water body (13 km in length) was evaluated as impaired and included on the Mississippi 303(d) list of impaired water bodies. As such, the EPA 319 (h) program, through the Mississippi Department of Environmental Quality selected this water body and its associated watershed for landscape improvement, with the goal of moving towards improving the lakes water quality, meeting associated evaluated total maximum daily loads, and ultimately de-listing the water body for total suspended sediment (TSS) impairment. A study was undertaken for 2 years to evaluate and document appropriate changes to the total suspended sediment loads (mg/L) and overall lake turbidity. These two objectives were analyzed with monthly surface sampling events of turbidity using automated sampling technology (Eureka - Manta 2, Automated Data-son) as well as 20 random samples per sampling trip for TSS analysis. Results from a non-parametric Kruskal-Wallis analysis indicate a significant month-by-year effect on turbidity and TSS (Chi-square = 76.08, P = 0.001), but reach (Chi-square = 2.45, P = 0.784) and depth by reach (Chi-square = 2.44, P = 0.784) did not show significant effects on turbidity. There were no significant correlations between TSS and turbidity concentrations and two day, and seven day summed or mean rainfall. Spearman correlation analysis for TSS indicated significant correlations between TSS and mean two day (r²= 0.62, P= 0.002) and seven day (r²= 0.51, P= 0.014) wind speeds. All other variables used in the analysis did not show significant correlation with TSS (P> 0.05). This suggests that wind conditions, rather than rainfall predict the greatest variability in TSS and turbidity in Wolf Lake. These documented correlations between lake water column TSS and turbidity, and wind highlight the difficulties of demonstrating success in a short temporal period between project initiation and completion. Unmanageable environmental conditions (wind speed and direction), and limited temporal monitoring scales (1.5 years post BMP implementation) limit the possibility of demonstrating success of water quality improvement within Wolf Lake a 303(d) listed water body.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Floyd I.E., Orsi T.H.

The GV Sonny Montgomery Multi-Purpose Range Complex-Heavy (MPRC-H) is a training range, located within the Camp Shelby Joint Forces Training Center (CSJFTC), MS, and is used by armored and mechanized infantry and attack helicopter units. Construction of the range occurred in 2004 during a period of low regional precipitation. Lack or inadequate installation of sediment control structures (sediment fences and matting), combined with high daily rainfall over a 2 week period, led to extensive erosion within and around the range and sediment infilling of two parts of Davis Creek basin, immediately outside the MPRC-H. The impacted areas covered over 42 wetland acres and were infill with sediment 6-14 inches thick. Thereafter, proper erosion control structures were installed and natural remediation was selected as the most viable option for site regeneration.

The impacted areas outside the MPRC-H have been monitored since 2005, most recently in 2009. During the 2005 assessment, the absence of small vegetation was most obvious and the event lead to dramatic increases in turbidity within the Davis Creek tributary and subsequent downstream tributaries. Interestingly, elevated turbidity levels were noted for almost 2 years after the sediment control structures had been repaired and/or replaced. During our 2009 survey, it was determined that fluvial, overland runoff processes and infill compaction within the MPRC-H wetland have led to substantial reductions in the aerial extent (39%) and thickness (30%) of the sediment plume. None-the-less, even with this significant removal of material, the remainder may or may not be removed by natural processes over timescales of human and engineering interest. However, understanding the processes that have taken place in and around the MPRC-H should form a template for future sites to determine which remediation option, anthropogenic or natural, is most cost-effective and beneficial.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Wren D.G., Davidson G.R.

The effectiveness of erosion control measures is difficult to quantify, hampering the development of management practices and preventing accurate assessment of the value of erosion control structures over time. Surface erosion can vary widely over an area, particularly if gully erosion is present, and the use of sediments transported in streams for quantifying erosion is hindered by the highly variable nature of fluvial sediment loads. When a watershed drains into a lake, accumulated sediments have the potential to yield information about historic rates of sedimentation that can be used to evaluate the effectiveness of previous erosion control measures. In the present study, sediments from five natural oxbow cutoff lakes (Beasley, Washington, Wolf, Roundaway, Moon) in the Mississippi River alluvial floodplain were dated using ²¹⁰Pb decay rates and bomb-pulse derived ¹³⁷Cs with the goal of relating trends in sedimentation rate to reductions in erosion due to management practices. It was found that the radioisotope dating methods were best used in concert with known dates for implementation of management practices. Changes in sedimentation rate over time frames as short as 15 years were detectable. Larger lakes generally showed smaller changes in sedimentation rate as may be expected because of the expense and difficulty in applying management practices over larger areas.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Locke M.A., Knight S.S., Shields Jr. F.D., Moore M.T., Lizotte R.E., Murdock J.N., Cullum R.F., Bingner R.

Research by the USDA Agricultural Research Service (ARS) National Sedimentation Laboratory includes long-term and comprehensive evaluations of conservation practices and assessment of their influence on the water quality and biological health of watersheds in the Mississippi Delta alluvial plain, with extensive plans for future projects beginning to be implemented. Existing ongoing research is part of the ARS national Conservation Effects Assessment Project (CEAP). Data from these studies include soil quality characterizations, cropping patterns, management practices, topography, climate, runoff, ecological assessments, and lake water quality. In addition to direct applications toward resource management, data have also been used in validating predictive computer models of agricultural practices such as AnnAGNPS. With contaminants from agricultural watersheds cited as major contributors to environmental problems such as hypoxia in coastal areas, loss of ecosystem services, and soil and water quality degradation, ARS research includes monitoring of water quality and fish resources and evaluation of runoff from areas where management practices such as CRP and buffer strips are implemented. Focus of the water quality evaluations include not only lacustrine (Beasley Lake project formed from a 915-ha oxbow lake watershed with a 15-year extensive data base) and riverine systems that are part of a network of ARS projects along the Mississippi River that contribute to the Mississippi River Basin Initiative, but also within-field and edge-of-field studies of vegetated agricultural ditches and water retention structures. Planned new research will include ecological assessment of three Mississippi Delta watersheds for the development of science-based TMDLs. This project will be focused on watersheds currently impaired by elevated suspended sediment and turbidity, low dissolved oxygen (DO) concentrations, nutrients and hydrologic perturbations. Watersheds will be monitored for up to three years to gather baseline information and document temporal variability of stream water quality and biological parameters. Following this, each watershed will be subjected to treatment intended to either reduce or increase biotic impairment. Candidate treatments include flow augmentation, flow diversion through wetlands, the establishment of within stream structures, agronomic conservation practices or simulated pollution events. Resulting changes in water quality, habitat and biological community will be observed. In addition to general ecological benefits, this research in the Mississippi Delta is expected to benefit a large number of stakeholders, including farmers, Delta FARM, Delta Wildlife, Delta Council, Mississippi Soil and Water Conservation Service, the Yazoo-Mississippi Delta Water Management District, Mississippi Department of Environmental Quality, USEPA, and USDA-NRCS.

Final Project Report, Project 2009MS86B

Year: 2010 Authors: Kaminski R.M., Spencer A.B.

A successful and increasingly applied conservation practice in the Lower Mississippi Alluvial Valley (MAV) to mitigate loss of wetland wildlife habitat and improve water quality has been development and management of "moist-soil wetlands." Whereas a primary goal of moist-soil management is to provide abundant food resources for waterfowl and other waterbirds in the MAV and elsewhere on the wintering and migrational grounds, this conservation practice has the potential to provide ecosystem services critical to restoring ecosystem functions in the MAV. Within the MAV, strategic location of natural moist-soil wetlands amid farmed lands can reduce dispersal of sediments and other nutrients into surrounding watersheds. Moreover, a significant potential exists for native crayfish (Procambarus spp.) harvest in moist-soil wetlands in the MAV. Our current research is designed to quantify nutrient management and crayfish harvest as ecosystem services provided by moist-soil wetland management in the MAV. During spring 2009, we estimated baseline water quality parameters and average daily yield of crayfish from 9 moist-soil wetlands in Mississippi. Mean NO₃-N, NH₄-N, and PO₄-P concentrations were variable whereas total suspended solid concentrations decreased over time. Average daily yield of crayfish was 1.75 kg ha^-1 (CV = 16%, n = 9). We continued our study in spring-summer 2010 in wetlands in Arkansas, Louisiana, and Mississippi. Preliminary estimates of average daily yield of crayfish in 2010 was 2.18 kg ha^-1 (CV = 30%, n = 15). In July 2010, we installed water quality monitoring stations at 6 wetlands and 6 agriculture fields. We will use the data from these stations to estimate and compare monthly loads (kg ha^-1) of nutrients and solids from moist-soil wetlands and flooded agricultural fields. Quantifying these ancillary ecosystem services of moist-soil wetlands will encourage further establishment and management of these wetlands in the MAV and elsewhere for wildlife and associated environmental benefits.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Mason P.

A regional groundwater flow model has been built as a tool to better understand the system flows and to project future water levels in the Missisippi River Valley alluvial aquifer (MRVA). This is a highly productive aquifer which supports vast amounts of agriculture and aquaculture in northwest Mississippi. Water levels are declining in this aquifer and will be of increasing concern in the future.

To quantify discharge, the model incorporates a method of estimating pumpage for agriculture and aquaculture, based on crop distribution patterns and rainfall-response factors.

Recharge to the aquifer is complex and unusual, since a widespread impermeable surficial unit restricts rainfall infiltration in most of the Delta plain. Good calibration was achieved only when the model fully accounted for recharge data from several sources. Positive recharge sources are: groundwater in the adjoining formations on the eastern bluff hills line, rain infiltration through the alluvial fans along the bluffline, and rain infiltration through sandy areas along the Mississippi River.

Other sources serve as both discharge and recharge areas for the aquifer, depending on season and/or location. These are: the Mississippi River, the underlying Tertiary aquifers (Cockfield and Sparta), the major rivers and the bluffline streams.

The base model period, built from known data for streams, precipitation, crops, and water levels, etc. ran 1996 through 2006. On average, the aquifer lost about 230,000 acre-ft of water per year from 1996 to 2006. During this time, pumpage per season averaged about 3 million acre-feet, with a minimum of 1.7 million acre-feet in 2002 and a maximum of 4.5 million acre-feet in 2000. Rainfall infiltration averaged about 2.4 million acre-feet per water-year, with a low of 1.9 million acre-feet in 1998 to a high of 3 million acre-feet in 2003. Over the ten year period, there were 2 years during which rainfall infiltration exceeded pumpage. In 8 of the years pumpage exceeded rainfall infiltration.

Several scenarios have been run from 2009 water levels forward, simulating conditions 20 years into the future, and the results of these are presented.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Barlow J.R., Clark B.R.

The alluvial plain in northwestern Mississippi, locally referred to as the Delta, is a major agricultural area, which contributes significantly to the economy of Mississippi. Land use in this area can be greater than 90 percent agriculture, primarily for growing catfish, corn, cotton, rice, and soybean. Irrigation is needed to smooth out the vagaries of climate and is necessary for the cultivation of rice and for the optimization of corn and soybean. The Mississippi River Valley alluvial (MRVA) aquifer, which underlies the Delta, is the sole source of water for irrigation, and over use of the aquifer has led to water-level declines, particularly in the central region. The Yazoo-Mississippi-Delta Joint Water Management District (YMD), which is responsible for water issues in the 17-county area that makes up the Delta, is directing resources to reduce the use of water through conservation efforts. The U.S. Geological Survey (USGS) recently completed a regional groundwater flow model of the entire Mississippi embayment, including the Mississippi Delta region, to further our understanding of water availability within the embayment system. This model is being used by the USGS to assist YMD in optimizing their conservation efforts by applying various water-use reduction scenarios, either uniformly throughout the Delta, or in focused areas where there have been large groundwater declines in the MRVA aquifer.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Massey J.H.

The goal of this on-going project is to determine the feasibility of using multiple inlet plus intermittent irrigation to reduce water and energy use in Mid-south rice irrigation. Intermittent rice flooding improves rainfall capture and reduces over-pumping by maintaining rice flood heights at less-than-full levels. Depending on soil conditions, weather, and crop stage, the targeted intermittent pumping pattern allows the flood to naturally subside over a period of five to ten days before re-initiating irrigation, resulting in a fully saturated (not dry) soil surface. Field studies are being conducted at four Mississippi producer locations location in Boliver, Coahoma, and Sunflower counties in the Mississippi River Valley delta. Seasonal water use was measured using flow meters in commercial rice fields ranging in size from ~30 to 70 acres. Rainfall inputs were determined using rain gauges at each field location. Rough rice yield and grain quality determined for the upper and lower portions of each paddy of each field were not different, indicating that intermittent flooding does not result in agronomic losses relative to continuous flood. The studies show that when coupled with multiple inlet irrigation, intermittent rice irrigation uses ~20% less water than multiple inlet irrigation alone and only ~5% more than zero-grade irrigation. Having no slope, zero-grade fields are the ‘gold standard’ for Mid-south rice production in terms of water use. The advantage of the intermittent flood over zero-grade is that water-logging of rotational crops often associated with zero-grade fields is avoided. Rice is typically grown with soybean in a 1-yr rice, 2-yr soybean rotation. The presentation will also summarize results from using the USDA’s Phaucet irrigation optimization program designed to improve soybean irrigation efficiency.

Proceedings of the 40th Annual Mississippi Water Resources Conference

Year: 2010 Authors: Young A., Moran M., Diaz-Ramirez J.

The emergence of excess nutrient loads in water bodies in the Mississippi Delta has led to their appearance on the 303(d) listing of impaired waters for Mississippi. This project aims to develop and improve analytical tools for the evaluation of nutrient load reductions expected from the implementation of best management practice (BMPs) on some of these water bodies in the delta. In compliance with the Delta Nutrient Reduction Strategies developed by Delta Farmers Advocating Resource Management (F.A.R.M.) and the Mississippi Department of Environmental Quality (MDEQ) the first step in this process is the characterization of the watershed including geology, land use, soil type, hydrology, and water quality issues. The area of study for this project is three sub watersheds within the Big Sunflower Watershed. The Big Sunflower Watershed is the largest watershed in the delta at 221270 acres and is a part of the Yazoo River Basin. Significant characteristics for the watershed were found to be a dominance of agricultural land, poorly drained soils, and the persistence of impaired waters due to extreme nutrient loads. Examination of historical trends shows a decline in the state of the groundwater aquifer and the constant persistence of agricultural land as the major land use type. Availability of nutrient data for the watershed is incredibly limited making it difficult to draw conclusions by comparing past flow and land use data to the occurrence of nutrients in the water bodies of the Big Sunflower Watershed.