Application of a Hydrologic Model to Assess the Effects of Cloud Seeding in the Walker River Basin of Nevada

Abstract

The focus of this study is to use a physically-based, distributed hydrologic model to estimate the impacts of cloud seeding efforts on the streamflow generated within the areas of the Walker River Basin targeted by the Nevada seeding program. The hydrologic model is calibrated using GIS information, model default values, and manual calibration to fit observed streamflow at a USGS surface water station within the Walker River Basin. The calibrated model is then used in two case studies that are designed to simulate a non- seeded condition and a seeded condition with a 10% increase in precipitation on the five target areas. The results from the two modeling case studies indicate that the additional precipitation applied in the seeded case results in increases in evaporation and runoff from the target areas but does not significantly impact the storages of moisture in the groundwater and soil zone for all of the five target areas. The fraction of seeding-increased precipitation that resulted in streamflow varied from 49% to 89% among the different target areas. The remainder of the additional precipitation resulted in evapotranspiration from the target areas.