Analysis of the Impact of Changing Weather Phenomena on the Timing and Discharge of the Uncompahgre, San Miguel, and Animas Rivers, Colorado
— K.A. Kelkar, J.R. Giardino, J. Vitek, and G. Gamache

The limited availability of fresh water coupled with growing agricultural and urban demands in the western United States is forcing cities and towns to be heavily dependent on montane water resources for domestic supplies. Thus, predicting the impact of weather trends and variability on water resources is necessary to ensure that current and future demands for water can be met. Understanding the hydrologic response related to weather phenomena in montane regions, requires an answer to the question: Do weather phenomena reduce or shift the timing and volume of montane streamflow regimes? Time-series analysis and General-Least-Squares (GLS) regression were used to determine if a link exists between weather phenomena and the timing and volume of discharge for the Uncompahgre, San Miguel, and Animas Rivers in southwestern Colorado. Time-series analysis did not reveal significant (α = 0.05) trends in the timing of streamflow for the three drainage basins. With GLS regression, at a level of 0.99 significance, the selected variables explained that 56% of the variance was associated with the onset date of the spring-pulse, 84% of the variance was associated with the timing of peak streamflow, and 82% of the variance was associated with the date at which elevated streamflow ends, or subsides. Our research illustrates the necessary foundation that can be used to determine site-specific changes in streamflow regimes to make critical water resource management decisions more accurate.