Managed Aquifer Recharge As a Key Element in Sonora River Basin Management, Mexico

Arid regions frequently have competing demands for scarce water mainly for urban supply and irrigation. This paper presents a decision support system (DSS) as an instrument to find the optimal scheme for management of water resources from multiple supplies using managed aquifer recharge (MAR). The DSS capabilities are demonstrated through its application to the Sonora River basin. The watershed is located in Northern Mexico and has a wide variety of agricultural zones and many small towns along the river. The most important urban center is the city of Hermosillo with a concentrated water demand for urban and industrial uses. The DSS includes the hydrological modeling of the entire system, stream flow in rivers, the groundwater-flow model including MAR, and the characterization of the water quality from various sources. The result from this study establishes that it will be difficult to satisfy the increasing demand for water using the current supply-and-demand-allocation schemes. Alternative sources are thus needed to mitigate the future difference between supply and demand. The MAR with treated wastewater represents an option that could sustain development of urban water supply and irrigation within this basin. It is concluded that the best strategy (least groundwater-storage depletion) is to restrict irrigation and allocate all the effluent from the wastewater treatment plant (WWTP) to recharge the aquifer through infiltration lagoons. However, if there is not a limitation to irrigation, urban demand increases at 1.7% per year and without artificial recharge, the aquifers will be depleted in 25 years. Alternatively, if the WWTP effluent is shared between agriculture and MAR, it is possible to allow irrigation of 2,800 ha with small groundwater depletion. The DDS also allows for studying the potential improvements in water quality and resilience to global climate change.