Multi-Target Calibration with a VIC Hydrologic Model: Impacts of Climate Change and Risk Assessment in the Colorado River Basin

The Variable Infiltration Capacity (VIC) model is applied to the headwaters of the Arkansas River (Colorado Springs) in the USA for the purpose of water supply evaluation. Modeling the hydrologic regime of the Arkansas River is a challenge due to the large number of diversions and regulations that might impact the natural streamflow. Since the Arkansas River headwaters are snow-melt dominated, a snow cover dataset can provide additional information during the model calibration process. Remote sensing snow data have been successfully used in previous studies coupled with hydrologic modeling to improve calibration results. Using the daily snow data acquired from the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite, and this study tests different calibration schemes to determine the most suitable calibration target(s) for the Colorado Springs. First, the VIC model is calibrated to streamflow and snow alone, and then a mutli-objective optimization is utilized to calibrate the model to streamflow and snow simultaneously. A well calibrated hydrologic model can be employed particularly for climate change assessments to inform decision makers about water availability and water supply under different climate conditions. This study will provide such information to Colorado Springs in which development in terms of water supply is expected to grow considerably; increases in demands are projected to be 28% higher than the present demands (approximately 102 billion gallons) by the year 2050.