Hydrology and Hydrogeology in the Cordillera Blanca

While the hydrology of the Cordillera Blanca is often related to the extensive glacierization, this seasonally dry tropical mountainous region also distributes many other hydrologic and hydrogeologic features over extensive topographic relief. Moreover, the water flows and accessible reservoirs within this varied landscape relate to coupled natural and human processes that impact the water availability, quality and use. Accelerating glacier retreat has been a primary focus of researchers for a couple decades, but since many tributary streams of the Santa River (Rio Santa) have already passed peak water, other hydrological processes are gaining importance, such as groundwater—stream water interactions, water access and demand, and water quality. This chapter presents an overview of the hydrological and hydrogeological systems that preside over water resources from the glacierized valleys of the Cordillera Blanca. After describing the regional hydrosphere, including the hydroclimatic controls, seasonality, runoff regimes, reservoirs, fluxes and water uses, the impact of ongoing climate changes is discussed, and the future challenges ahead. An emphasis is placed on taking an integrated hydro-social modeling approach that requires integrating human variables into assessments of future water access and quality.