Streamflow values must be synthesized for locations where flow measurement stations, in applications such as the West Virginia SWAP program, are lacking or where only intermittent measurements are available (West Virginia Department of Health and Human Resources, 1999). This research describes an effort to improve upon the current synthetic streamflow model by incorporating geomorphic, geologic, and hydrogeologic measurements. Principal components analysis (PCA) was used to derive a set of master variables that characterize stream flow in West Virginia based on historical data from 29 watersheds. The relationships between variables affecting stream flow were also analyzed using cluster and correlation analysis to derive an optimum set of variables for predicting stream flow in the state. Based on this analysis, there are two categories of watersheds in West Virginia. The first is strongly correlated to climatic variables: precipitation, temperature, elevation, and groundwater recharge. The second is strongly correlated to two geomorphic variables; watershed slope, and percentage of forested area. The spatial distribution of the watershed groupings shows that watersheds dominated by the climatic component are located along the Allegheny Front while watersheds dominated by the geomorphic component are located in the Allegheny plateau and Valley and Ridge physiographic provinces
