Groundwater Drought Assessment of Major U.S. Aquifers Using Grace Measurements

Abstract

Precipitation is a major source of groundwater recharge, and when drought occurs knowing the timing of recharge is crucial. This project seeks to quantify the lag-time between the end of meteorological drought and groundwater drought using the Standardized Precipitation and Evapotranspiration Index (SPEI) and Gravity Recovery and Climate Experiment (GRACE) derived groundwater storage for major aquifer systems across the U.S. Timeseries were created for both the derived groundwater storage and SPEI for the period of April 2002 to June 2021. Each aquifer system had a meteorological drought occur at least three times during the study period, with higher rates of occurring in the western U.S. The lag time between the start of the two types of droughts for these aquifer systems is between zero and one months, while the lag time between the end of these types of droughts is more widely varied, between zero and eight months.