Daniel P. Ames

Groundwater modeling is a useful tool for assessing sustainability in water resources planning. However, groundwater models are difficult to construct in regions with limited data availability, areas where planning is most crucial. We illustrate how remote sensing data can be used with limited in situ data to build and calibrate a regional groundwater model in the Goulbi Maradi alluvial aquifer in southern Niger in Western Africa. We used data from the NASA Gravity Recovery and Climate Experiment (GRACE) satellite mission to estimate recharge rates, the primary source of water to the aquifer. We used the groundwater storage changes obtained from GRACE data from 2009 to 2021 to establish an overall water budget. We used this water budget to back-calculate groundwater withdrawals from pumping in the region. There are only very limited historic data on withdrawals. This approach allowed us to calibrate the model and use it as a predictive tool to analyze the impact of various assumptions about future recharge and groundwater extraction patterns associated with the development of groundwater infrastructure in the region. The results indicate that water extraction from the Goulbi Maradi alluvial aquifer is sustainable, even if current groundwater extraction is increased by up to 28%.