Integrating Environmental Flows into Multi-Objective Reservoir Management for a Transboundary, Water-Scarce River Basin: Rio Grande/Bravo

Abstract

Integrated water management seeks to balance the interests of multiple stakeholders who desire many end-uses for water within the context of institutions and regulations. This problem is particularly complex in transboundary and water-scarce basins. In the Big Bend region of the Rio Grande/Bravo, an arid, monsoonal climate combines with multiple human and environmental water demands and established treaty requirements to stress available water resources. We analyzed reservoir operation strategies in the basin to integrate environmental flow (EF) considerations into existing management objectives using a linear programming model to assess reservoir operation policies. Five potential EF regimes are evaluated for improving aquatic and riparian habitat in the Big Bend region. The model uses the historical hydrologic record of river inflows, data for flood control and bi-national water allocation requirements, and parameters for human demands and infrastructure; to compare current and optimized operations of Luis L. Leon reservoir for multiple objectives. Results indicate that alternative operational policies for monthly reservoir storage (compared to historic values) can increase EF allocations without affecting water deliveries or treaty allocations. Some tradeoffs may exist, however, in managing reservoirs for both EFs and flood control. Our approach informs management strategies for the water-stressed basin that seek to incorporate environmental goals into existing infrastructure and operations.