ASSESSMENT OF A DISTRIBUTED HYDROLOGICAL MODEL APPLIED TO A GLACIERIZED BASIN IN THE CORDILLERA BLANCA, PERU

Glacier retreat may have substantial impacts on water resources for heavily populated regions, such as the Peruvian Andes. Water vulnerability is high in this region prompting a need for better predictions of glacier contributions to streamflow. This study in the Llanganuco basin, Peru, seeks to determine how well the Distributed Hydrology Soil Vegetation Model (DHSVM) with a newly integrated glacier component predicts dry season contributions of glacier meltwater to streamflow. Field data for calibration and validation were collected during the 2011 dry season. We installed two stage height recorders, collected water samples for use in an isotopic mixing model, and also acquired meteorological information needed to run the model. We also mapped major soil types and defined vegetation classes in the basin. The three main objectives of this ongoing effort are to: (1) map glacier extent and its changes over the past 25 years; (2) determine the fraction of stream discharge derived from glacier melt in the basin; and (3) assess the accuracy of modeled stream discharge during the low flow season. Estimated contributions of glacier meltwater, coupled with discharge measurements, will provide an important first order check on the model. This study will be a valuable step in a complete model validation, providing important diagnostic information for incremental improvements to a model, which will eventually be used for similar glacierized basins in the Canadian Rocky Mountains and Himalaya.