Climatic variations in summer precipitation and their impacts on streamflow in the Michigan Lower Peninsula

Variations in the streamflow component of the Great Lakes hydroclimate have important implications for regional climate feedbacks, water resources, water geochemistry, and ecological functions. A Mann-Kendall trend analysis of stream gage data throughout Michigan's lower peninsula shows recent decreases in the annual Richards-Baker Flashiness index, which is an indication of the frequency and rapidity of short term changes in streamflow. Streamflow flashiness can be impacted by land use/management practices, but also by the characteristics of precipitation input to the hydrological balance of the watershed. In order to determine the role of summer precipitation on the changing streamflow flashiness, summer precipitation frequency and intensity, sorted by watershed size, are analyzed using the United States Historical Climatology Network over the time period 1955 to 2009. Results indicate that shorter duration, more intense storms are less effective at groundwater recharge than more moderate and frequent storms.