On-farm irrigation reservoirs in two Arkansas critical groundwater regions: A comparative inventory

Authors: YAEGER, MARY - Arkansas State University; Reba, Michele; Massey, Joseph; Adviento-Borbe, Arlene

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/3/2017
Publication Date: 12/28/2017
Citation: Yaeger, M.A., Reba, M.L., Massey, J., Adviento-Borbe, A.A. 2017. On-farm irrigation reservoirs in two Arkansas critical groundwater regions: A comparative inventory. Applied Engineering in Agriculture. 33(6):869-878. https://doi.org/10.13031/aea.12352.
DOI: https://doi.org/10.13031/aea.12352

Interpretive Summary: Arkansas ranks third in the nation in terms of irrigated cropland and relies heavily on the Mississippi River Valley alluvial aquifer for irrigation. Two critical groundwater areas have been identified in the Cache River and Grand Prairie. Irrigation reservoirs have been constructed on farms to capture and store surface water to help offset groundwater use but no information exists on the exact numbers and locations of these reservoirs. This study addressed this knowledge gap. Water planners and managers will benefit from accurate and timely knowledge of surface water resources to determine progress made in assessing aquifer decline and potential needs for future construction. In the larger Grand Prairie area, where aquifer decline was identified earlier, 632 reservoirs were identified for a total surface area of 23,000 acres. In the Cache River area, 143 reservoirs were identified for a total surface area of 6,100 acres. Average reservoir size in both regions was 14.6 ± 20 ha and ranged from 1 to 265 ha. Reservoir area comprised approximately 3% and 1% of the areas of potentially-irrigated cropland in Grand Prairie and Cache River regions, respectively.

Technical Abstract: Arkansas, which ranks third in the nation in terms of irrigated cropland, relies heavily on the Mississippi River Valley alluvial aquifer for irrigation. Two critical groundwater areas have been identified, with one along the Cache River in northeast Arkansas and the other in the Grand Prairie in central AR. Thus, there has been a call to develop surface water resources for irrigation, and as a result, on-farm irrigation reservoirs have been constructed to capture and store surface water. To assess the current state of surface water development, a remote-sensing survey using National Agricultural Imagery Program data was conducted to provide an inventory of the locations and surface area of on-farm reservoirs in the two critical groundwater areas. Expert consultation and on-site inspections were used to confirm the remote sensing results. In the larger Grand Prairie area, where aquifer decline was identified earlier, 632 reservoirs were identified for a total surface area of 9,300 ha. In the Cache River area, 143 reservoirs were identified for a total surface area of 2,000 ha. Average reservoir size in both regions was 14.6 ± 20 ha and ranged from 1 to 265 ha. Reservoir area comprised approximately 3% and 1% of the areas of potentially-irrigated cropland in Grand Prairie and Cache River regions, respectively. To place this reservoir inventory in a practical context, the reservoir service areas can be combined with some estimate of total irrigated cropland to get an idea of how much of that land could be irrigated with surface water instead of groundwater. From the NASS CDL, approximately 90,600 ha rice, and 203,000 ha soybean, maize, and cotton, combined, were grown in the Grand Prairie study region in 2015. Similarly, 82,730 ha rice, and 110,220 ha soybean, maize, and cotton combined were grown in the Cache River study region. Assuming that 100% of rice was irrigated and 89% of soybean, 98% of maize, and 93% of cotton were irrigated at least once during the 2015 growing season (USDA-NASS, 2014), the portions of potentially-irrigated cropland that were irrigated would be approximately 273,000 ha in the Grand Prairie and 181,000 ha in the Cache River study regions. Given these assumptions, reservoirs existing in 2015 would be able to service approximately 32% and 9% of irrigated cropland in the Grand Prairie and Cache River regions, respectively.