Sustaining aquifers economically in the face of hydrologic, institutional, and climate constraints

Aquifers supply water to millions of farms, thousands of cities, and billions of people worldwide. Water use and economic activity in aquifer-dependent regions cannot be sustained if groundwater levels are not stabilized. This article addresses a question relevant to these regions internationally: how can water scarce areas reduce aquifer depletion while supporting the many economically and institutionally important uses of groundwater, which serve as a critical source of supply in many parts of the world with limited or seasonal precipitation which could become more pronounced in the face of future climate stress. Facing that challenge, this work presents a framework for discovering measures to hydrologically stabilize aquifers that control economic losses while respecting local institutional constraints. It advances our capacity to discover measures to efficiently, equitably, and sustainably allocate burden sharing that protects aquifers while adapting to hydrologic, economic, and institutional characteristics of an affected community. Results of this work show that for the aquifers investigated, present practices of groundwater use are unsustainable and finds that alternative practices are possible. It provides scenarios describing such practices and also determines their hydrological and economic consequences. Finally, it shows how these results can feed into policy debates over the several water-sharing arrangements. This work makes several incremental contributions: calibrating modelled pumping patterns to the historical baseline, controlling economic costs of achieving hydrologic sustainability, respecting institutional constraints governing equitable burden sharing, presenting an approach with powers of generalizability, and using routinely collected data. While the approach and findings are illustrated for two aquifers in Africa, its approach carries some generalizability. All data, variables, equations, constraints, and results are included as appendices.