Exploring the Influences of Water-Saving Practices on the Spatiotemporal Evolution of Groundwater Dynamics in a Large-Scale Arid District in the Yellow River Basin

Abstract

Water-saving practices (WSPs) have been recognized as an effective measure for reducing agricultural water use and alleviating regional water shortages in arid irrigation districts. However, WSPs have also reduced groundwater recharge, thereby causing the depth to groundwater table (DGT) to increase. Therefore, characterizing the impact of WSPs on the spatiotemporal variability in the DGT is of paramount importance for protecting limited groundwater resources. Based on monthly DGT observation data collected from 1990 to 2015 at 206 observation wells in the Hetao Irrigation District (HID), located in Northwest China with an arid climate, the spatiotemporal variations in DGT before and after the application of WSPs were analyzed using the empirical orthogonal function (EOF) method, and the major driving factors of the spatiotemporal DGT changes were also identified using comprehensive approaches. The EOF method revealed four major spatiotemporal DGT patterns both before and after WSPs were applied; these patterns explained 71.39% and 73.99% of the total variability in the HID before and after WSPs application, respectively. In addition, the main controlling factors affecting the DGT dynamics were different before and after WSPs were applied. In terms of the associations of the DGT with the impacting factors, the meteorological factors had the strongest impact on the DGT changes on the long-term scale of 64 months; however, irrigation played a leading role at the seasonal and semiannual scales, especially after WSPs application. The soil texture significantly impacted the spatial DGT patterns, particularly at depths above 150 cm. This study provides a scientific basis for the rational development of local groundwater resources and the scientific management of water-saving irrigation measures.