Climate change and development impacts on the sustainability of spring-fed water supply systems in the Alto Beni region of Bolivia

In the Alto Beni region of Bolivia, as in other locations of the developing world, gravity-fed water supply systems provide a significant portion of domestic water needs. However, sustainability of these sources depends on whether discharge can be sustained to accommodate future water needs. There is a perception that agricultural expansion in the region is resulting in reduced spring discharge. To investigate this claim, we incorporate low-cost field methods for hydrologic data collection and evaluate two satellite-derived precipitation data products (CMORPH and TRMM-3B42) for input to a hydrological model used to predict recharge rates in eleven watersheds under scenarios of climate change and agricultural expansion. The stressors on the local water supply examined in this study are changes in land use and climate, along with increases in population and consumption, and improvements in water and sanitation coverage. Although predicted changes in runoff range from -69% to +137%, depending on the climate and land use scenario, recharge is predicted to decrease under all scenarios (by 28% to nearly 100%) between the periods of 1970-1999 and 2070-2099. The predicted impacts from climate change are considerably larger than those from agricultural expansion, calling into question local perceptions that spring flow has declined because of changes in land use from agricultural growth. The ratio of water use to availability under most scenarios of climate change and water and sanitation service expansion suggests that use of groundwater is sustainable in the region when considering the entire recharge to the watersheds. However, the small recharge areas of the springs may result in insufficient recharge to support planned water and sanitation expansion unless new water supplies are developed. (C) 2012 Elsevier B.V. All rights reserved.