On-Farm Storage Reservoir Water as a Potential Water Source in Managed Aquifer Recharge in Eastern Arkansas
Tuesday, December 5, 2017: 11:20 a.m.
The Mississippi River Valley Alluvial Aquifer is the primary source of irrigation for agriculture in eastern Arkansas. However, alluvial aquifer declines in Arkansas, mainly attributed to irrigation, continue to impact production costs and groundwater sustainability. Agricultural producers are constructing on-farm reservoir - tailwater recovery (R-TWR) systems to reduce their reliance on groundwater. Reservoirs store surface water and, when coupled with a tailwater recovery system, underground pipes, and groundwater wells, function as a complete irrigation system. Currently, more than 700 R-TWR systems have been identified in two eastern Arkansas areas designated as Critical Groundwater Areas (CGA). In relation to water conservation measures, it would also be beneficial to devise methods that increase aquifer recharge. Infiltration (injection) galleries have been suggested as a strategy for managed aquifer recharge on site. Infiltration galleries could be installed within the unsaturated zone of the alluvial aquifer, which has expanded in CGA due to declining groundwater levels. Preferential gallery locations include areas with a thin confining clay layer and with a large enough depth to groundwater for sufficient treatment time in the unsaturated aquifer. On-farm reservoir water, which primarily consists of winter-spring precipitation, could serve as a source of recharge water during the non-growing season. The quality of the injected reservoir water would need to be improved through soil aquifer treatment within the unsaturated sand lithology before reaching the water table. The objective of this research is to identify the potential of R-TWR systems to enhance water quality, while also considering reservoir infrastructure, orientation, age, erosion control, etc. Initial water quality results, including herbicide concentrations, will be presented. Potential testing locations for infiltration galleries which reflect areas that have a thin confining clay layer, a suitable depth to groundwater, and an adjacent reservoir water supply within the Cache River CGA will also be discussed.