Space-time estimation of the distribution of potential recharge in the Toluca Valley

Abstract

Estimating potential recharge is essential to water resource management, urban/agricultural development planning, and the definition of pumping rates to prevent or mitigate aquifer overexploitation. In the Toluca Valley, high extraction rates have induced piezometric declines accompanied by a water imbalance exceeding the average annual recharge volume. In this study, a daily soil moisture balance was developed for estimating historical and future potential recharge. The analysis period includes 1980 to 2021 and a projection until 2050 based on three probable scenarios of precipitation, temperature, and urban growth. The results indicate an average annual recharge volume of 369.5 Mm3 with a 174.5 mm/year rate, reaching 355.7 mm/year in wet seasons. The spatial distribution suggests a recharge conditioned in the mountainous areas mainly by the climatology and in the center of the Valley by the land use modification. Urban sprawl is a significant factor in increased runoff and the gradual decrease in interception and actual evapotranspiration. The decrease in recharge is a constant in the potential future recharge scenarios. Compared to the historical average, a negative change of 16.59%, 19.99%, and 22.61% is projected for the best, moderate, and bad scenarios, respectively. The potential recharge rates obtained are an initial parameter in regional basin flow models and analyses.