Twin Cities Seminar
Climate Change as the Main Driver of Increased Streamflow in the Upper Midwestern United States
Increased streamflow and its associated impacts on water quality have frequently been linked to Land Use and Land Cover (LULC) changes such as increased tile drainage, cultivation of prairies, and adoption of soybean (Glycine max) in modern day cropping systems. However, recent analysis of streamflow records from 29 HUC 8 (Hydrologic Unit Code 008) watersheds in Iowa and Minnesota showed climate change (increased precipitation) instead of LULC change was the major driver of increased streamflow. The analysis was done through comparison of annual streamflow vs. annual precipitation relationships for the periods prior to 1975 (pre-change period) and after 1976 (post-change period). A statistical shift in annual relationship from the pre- to post-change period was assumed to be an indication of LULC changes whereas a lack of statistical shift suggested no change in the relationship and higher flows were mainly driven by increased precipitation. Since the publication of the original paper in Water Resources Research in 2015, a series of comments and our replies were published in 2016. In this presentation, I will cover the original analysis, our reply to comments and subsequent work that shows increased monthly streamflow linked to increased precipitation and an absence of LULC change impact on daily streamflow.