T107 Impacts of Land Use and Climate Change on Water Resources Sustainability (Posters)

Monday, 1 November 2010
8:00 AM - 6:00 PM
Hall D

USING A HYDROGEOMORPHIC APPROACH TO ASSESS THE IMPACT OF GLOBAL WARMING ON RECHARGE OF THE PUTAENDO AQUIFER IN THE CENTRAL CHILEAN ANDES

Paper number: T107-6
Program: Technical Sessions
Time: 8:00 AM – 6:00 PM

Authors

Abstract

The population of Central Chile is dependent on a water supply primarily fed by snowmelt. During the winter, the water supply is mainly surface water whereas during the dry season surface flow is supplemented with groundwater to meet human needs. In a climate change scenario, glaciers will retreat and snowmelt, therefore, becomes a valuable resource for groundwater recharge. Today, global warming is accelerating the melting of the glaciers, which results in rapid surface runoff and minimum infiltration to the aquifer. Recharge of the aquifer depends on the precipitation regime, rates of runoff, evapotranspiration and water-rock interactions. Identification of the mechanism of recharge from snowmelt from a hydrogeomorphic point of view would be most beneficial for water management decision-making because surficial deposits in the area are prone to mass movement.

The study area is a Mediterranean semiarid watershed with 1,190 km2 and one of the least human-altered catchments in the region. Nevertheless, a reservoir system, which will connect with other reservoirs in the region, has been approved. The Putaendo aquifer, which is primarily dependent mainly on surface water for recharge, is characterized by a lithology that is horizontally and vertically heterogonous and is composed mainly of Cretaceous andesitic and porphyry lavas and andesitic breccias and tuffs. Dominant recharge sources are snowmelt and winter precipitation, which results in a marked seasonal variability.

We used Stella modeling to assess the interactions among the variables that control recharge of this aquifer. The results highlight the flow of water along pathways to storage controlled by various thresholds.