The analysis of the trends in hydro-climatic parameters of a mountainous catchment in the western United States

Numerous investigators have reported changes in patterns of snow deposition and melt in the western US. The Reynolds Creek Experimental Watershed (RCEW) provides us the opportunity to evaluate these changes by looking at 40 years of data from multiple sites representing different elevation and site conditions. In this study we analyze the data form the three long term weather sites established in 60's and investigate the trends present in hydro-climatic parameters (mostly temperature, precipitation and humidity) on a daily, monthly, seasonal and annual basis, over the period of data records. Preliminary analysis of the temperature data shows that over the 40 year period there has been an increase in average temperature of 0.5 C at the lower elevation sites and 1.2 C at the high elevation site. This is characterized by the significant increase in average annual daily minimum temperature (by 1.2 to 1.5 C) and small increase in average annual daily maximum temperature. Preliminary analysis also shows an increasing trend in the vapor pressure. The runoff data from a set of nested catchments within the watershed will also be analyzed to check whether it is consistent with trends in hydro-climatic parameters. This study will be helpful in improving our understanding of climate variability and change, and its effect on water resources and the hydrology of semi-arid mountainous watersheds in the northwestern US.