Predicting Snowmelt Runoff on Sagebrush Rangeland Using a Calibrated Spur Hydrology Model

Abstract

ABSTRACT This study evaluates the ability of the SPUR (Simulation of Production and Utilization of Rangelands) model to predict monthly runoff on sagebrush watersheds where runoff is generated by spring snowmelt. Four watersheds in southwest Idaho were used to evaluate the model. Predicted monthly runoff was compared to actual runoff using a different part of the runoff record than what was used to calibrate the model. Results indicate that the calibrated SPUR hydrology model adequately simulates the volume and timing of monthly runoff for watersheds that have a relatively uniform snow cover. Transferability of the model for uncalibrated watersheds with uniform snow cover was also demonstrated. For most rangeland watersheds where snowmelt runoff is important, however, the spatial variability of snow cover is high; runoff is supplied mainly by one or more isolated drifts. The model works poorly under these kinds of conditions.