A system dynamic approach for managing transboundary water systems

Transboundary waters are vital to the sustainability and survival of human communities on the U.S.-Mexico border region, a nearly 2,000 mile-long arid zone in North America currently affected by climate uncertainties. We focus on the Rio Grande–Hueco Bolson (RG-HB; also known as Rio Bravo–Valle de Juarez in Mexico) water system, which is essential for the El Paso-Ciudad Juarez region. Water management in the region is characterized by limited and dwindling water supplies, increasing demands for water from multiple sectors, and a segmented governance system spanning two U.S. states and two countries. The region faces several drivers of change, including climate and increasing urban and agricultural demands. To aid with the sustainable management of water resources, this study describes the development of a water system model for the Hueco Bolson region that integrates data from monitoring and data from other numerical models with expert knowledge about the system. The model connections are developed in three different sectors for two countries: (i) reservoir system, (ii) surface water system, and (iii) aquifer water system, to simulate scenarios of change in water storage over time. With this model, we propose to answer several questions, including (1) What impact does climate change have on surface and groundwater availability in the region, (2) How do surface water allocations affect the groundwater pumping rates, (3) What is the future for agriculture in the region, and (4) what may be the likely effect of change in groundwater withdrawal rate on salinity. The key benefit of this system dynamic model is the fact that visual linkages between various water systems depict water movement for various audiences. Further, this model can be easily modified with new system connections to better represent this water system (e.g., add finer details) and integrated with similar socio-economic systems.