Spatiotemporal analysis of irrigated agriculture and groundwater depletion in four counties of West Texas

Groundwater supplied by the High Plains Aquifer (HPA) (also known as the Ogallala Aquifer) is a vital resource for irrigated cropland on the Southern High Plains (SHP) of West Texas. Large-scale irrigation on the SHP of West Texas has been steadily depleting the High Plains Aquifer since development (Haacker et al., 2015). The objective of this study is to gain a better understanding of the relationship between the saturated thickness of the HPA and center pivot irrigation fields in four counties of West Texas. The counties investigated were Castro, Hale, Lamb, and Swisher County. Saturated thickness data and existing center pivot irrigation field data were utilized from the Center for Geospatial Technology (CGST) at Texas Tech University. National Agriculture Imagery Program (NAIP) imagery from 2004, 2008, and 2016 were examined to create and update center pivot irrigation fields within the counties. National Agricultural Statistics Service (NASS) irrigated agriculture statistics from 1997 to 2017 were examined alongside the center pivot field data. Findings showed that essentially depleted saturated thickness areas expanded during the time span. The NASS irrigated agriculture statistics show that there has been a steady decrease in irrigated agricultural acreage, but the number of center pivots fields identified on imagery and the acreage associated with these center pivot fields is mostly unchanged. Center pivot acreage is also not decreasing where the saturated thickness is less than 30 feet. This discrepancy showing little change in center pivot field acreage and a significant decline in the NASS irrigated acreage strongly suggests that farmers are adopting strategies to reduce irrigation on center pivot fields.