A Hydroclimatology of the Green River Watershed in West-Central Kentucky During 1979-2010

The Green River Watershed, home to the Mammoth Cave system in west-central Kentucky, is a region heavily utilized for agriculture, which raises concerns about the transport of pollutants and the impact on water quality. The purpose of this study is to provide initial insight on relationships between streamflow within the Green River Watershed and the seasonal timing of precipitation, precipitation amount, and large-scale atmospheric circulation during the warm seasons (spring-summer) spanning 1979-2010. Daily precipitation data and synoptic maps were obtained from National Weather Service Cooperative weather stations and NOAA Daily Weather Maps series, respectively. Daily streamflow data were analyzed from the United States Geological Survey. Other large-scale atmospheric circulation data, which includes various teleconnections, were obtained from the Climate Prediction Center. Results indicate that mean basin warm-season rainfall for the POR is 642 mm. "Synoptic" precipitation days were the most frequent, contributed the majority (56%) of the seasonal average precipitation, and were statistically greater (95% CI) than all other events (except when compared to tropical events). "Synoptic" events were seen to have the greatest impact on streamflow, followed by "frontal" events and "moist tropical air-mass" events. However, lead/lag analysis of storm-type frequency and precipitation amount with respect to the timing of changes in streamflow must also be considered, and will be the focus of continued research. Lastly, there appears to be a weak relationship with increased basin-average precipitation and increased streamflow during El Nino cycles.