Increasing groundwater storage and maintaining irrigation through managed aquifer recharge

Abstract

Aquifers providing groundwater for agriculture are in many cases unsustainably managed, resulting in environmental degradation and socioeconomic impacts. In this context, strategies that contribute to recovering groundwater reserves and satisfactorily maintaining irrigation are essential. Los Arenales Aquifer (Spain) experienced a dramatic decline in groundwater level in the last quarter of the 20th century due to intensive agricultural abstractions. We assess whether this aquifer has recovered in recent years and the potential contribution of managed aquifer recharge (MAR). We evaluate the significance of groundwater level trends and their magnitude through the (regional) Mann-Kendall test and the Theil-Sen estimator. We also calculate the average groundwater level and explore factors that could influence the observed trends, such as MAR, land use, agricultural water demand, and water management measures. We also contrast two groundwater management regions located within Los Arenales Aquifer, namely Los Arenales (LA), which has implemented MAR, and Medina del Campo (MC), to obtain further insight into groundwater development. The hydro statistical analyses reveal a continuous drop in groundwater levels of about −1.3 m/year in LA between 1985 and 2001, followed by a consistent recovery. In MC, groundwater levels decrease in two out of three analysis periods. We show that MAR is spatially and temporally correlated with increasing groundwater level trends. Land use, agricultural water demand, and water management measures have remained similar throughout the analysis period or have a limited impact on groundwater use. Furthermore, the only significant water management measure MC differs from LA is MAR. These pieces of evidence point to MAR as the primary mechanism for replenishing Los Arenales Aquifer, showing the potential of this tool to recover stressed aquifers and sustain irrigation in the area and beyond.