Synoptic Classification as an Analytical Tool for Water Resources in the Colorado River Basin

The water resource concerns amid the persistent droughts in the southwestern United States are well documented. Regional watersheds such as the Colorado River basin have experienced strains from heightened demand and dwindling supply, necessitating costly conservation efforts among the growing urban and agricultural sectors. Among the more readily observable consequences of the drought are the record low water levels at the Lake Mead and Lake Powell reservoirs, which have seriously threatened the continuation of services from unrestricted water deliveries to hydroelectric power generation.

This study addresses the potential connection between the frequency and seasonality of upper level atmospheric circulation patterns to the drought conditions throughout the Colorado River basin. 500mb geopotential height values were collected from the NCEP/NCAR Reanalysis 1 dataset across a grid from 25-50°N and 125-100°W for the water years 1982-2012. The height values were then classified via principal component and cluster analyses to generate discrete circulation patterns. The frequencies of these patterns were then calculated by season, and statistically related through correlations and regressions to different metrics of water resources, such as reservoir levels, precipitation totals, and snowpack observations.

The circulation pattern frequencies were also compared to teleconnections with known regional climate impacts, such as the El Nino-Southern Oscillation and Pacific Decadal Oscillation, to further address potential relationships. Initial results of this study suggest a linkage between the persistence of ridge patterns and the likelihood of anomalously dry water years.