Modelling Groundwater Hydrological Drought and Its Recovery Given Natural and Anthropogenic Scenarios in South America

Abstract

Changes in groundwater recharge are a major concern in areas where increasing irrigated agriculture evidences unsustainable groundwater withdrawals despite low precipitation. This is worsening due to the increasing groundwater demand, which has intensified the magnitude of the hydrological drought by 10%–500%. Globally, 69% of groundwater abstraction is used for agriculture. Hence, South America is expected to face an unprecedented hydrological drought over the next 30 years due to rising agricultural withdrawals. Furthermore, attributing groundwater decline to groundwater pumping is an ongoing challenge (including scientific and technical/modelling challenges) that needs to be robustly addressed. To better understand the influence of anthropogenic water consumption on hydrological drought, with a particular emphasis on how irrigated agriculture impacts groundwater, we compared coupled and non-coupled versions of PCR-GLOBWB2.0 with MODFLOW regarding model selection and scenario comparison. We presented a natural and human scenario to understand the effects of hydrological drought on groundwater depletion and recovery. Using scenario comparison, the spatial patterns of human impact on the water cycle are identified by comparing groundwater flows, drought characteristics, and drought recovery. These impacted areas may help to understand their effects on human consumption, food security, and ecosystem demands.