Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Tagert M.L., Brock M.L., Paz J.O., Lo T.H., Krutz L.J.

Surface water is being increasingly used for irrigation in two agricultural regions of Mississippi—the Mississippi Delta region and northeast Mississippi. Producers in both areas rely on supplemental irrigation to meet crop water demands and reduce risk during the summer growing season. In the Mississippi Delta, groundwater from the Mississippi River Valley Alluvial Aquifer (MRVAA), a shallow subsurface aquifer, serves as the main source of water for irrigation. The MRVAA experiences the second highest daily pumping rate in the United States at 45,803 million liters per day. Over 60% of cropland in the Mississippi Delta is irrigated with groundwater from the MRVAA, and the continual increase in irrigation over the past few decades has resulted in declining MRVAA groundwater levels in the central Delta. It is difficult and expensive to access groundwater in northeast Mississippi, so surface water is the main source of water for irrigation here. In both regions of the state, surface water is obtained from both nearby rivers and streams and by capturing runoff from precipitation and irrigation in on-farm water storage (OFWS) ponds. Although there are differences in how OFWS systems are constructed in the Mississippi Delta and the northeast region of the state, systems in both regions provide the dual benefit of providing water for irrigation and reducing nutrients flowing off-site and into other water bodies in the watershed. Thus, there is a need to quantify the use of these systems to better measure their benefits on a watershed scale. From 2007 to 2020, a geospatial inventory showed that 794.5 hectares of land have been converted to surface water storage in OFWS systems in the Big Sunflower River Watershed (HUC 08030207) in the Mississippi Delta. The inventory was conducted using aerial imagery from the National Agricultural Imagery Program (NAIP), which was acquired from the Mississippi Automated Resource Information System (MARIS) and the United States Department of Agriculture (USDA)—Natural Resources Conservation Service (NRCS) Geospatial Data Gateway. A similar geospatial inventory is in progress for northeast Mississippi.