Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Venishetty V., Parajuli P.B.

Water quality due to anthropogenic change of land use and land cover (LULC) had been the major factors for impairment. Developing a critical understanding in hydrologic and water quality outputs with change in LULC is essential. Therefore the main objective of this study is to assess the effect of LULC change on surface water quality in Yazoo River Basin (YRB). YRB is the largest watershed in the state of Mississippi, spanning over an area of about 50,000 Km2, with varied land-use conditions, quantifying the change in LULC through in-situ methods was not practical. Soil and Water Assessment Tool (SWAT) a GIS based modelling application was used in this study. LULC layers had been obtained from 2002 to 2019 for Mississippi, were used to simulate streamflow, sediment, total Nitrogen (TN) and total Phosphorus (TP). Model performance was good and satisfactory in predicting hydrologic and water quality outputs respectively. Significant LULC change had been observed for Pasture, forests, and wetlands. There was a decrease in pastureland, from about 39% in 2002 to 7% in 2019. Alternatively, increase in forest land was observed from 2002 to 2019 from about 15% to 30% and increase in wetlands from about 1% to 15%. With increase in vegetation, a decreasing trend had been observed in flow, sediment, and nutrient loads; from 2002 to 2019. Therefore, results from this study proves that there is significant impact on water quality and quantity with temporal LULC change. LULC change at watershed scale for YRB had never been conducted before, hence this study could be a novel addition that could help in optimal use of natural resources and improve water quality.