On the influence of climate and land use change on monthly baseflow across the U.S. Midwest

This study examines the role played by changes in the climate system and land use in the observed monthly baseflow records (1966-2015) for 458 U. S. Geological Survey sites across the U.S. Midwest. We developed parsimonious statistical models in which monthly baseflow is related to any combination of four predictors (precipitation, temperature, antecedent wetness, and agriculture). We found that precipitation and antecedent wetness were the strongest predictors for all months, pointing to the role of water availability and infiltration in driving baseflow. Temperature was an important factor in the winter and spring where snow-melt processes are the most relevant. Agriculture was selected in the Corn Belt region during the growing season (from April to August) indicating that corn and soybean production in the Midwest promote baseflow discharge to streams. Overall, the goodness-of-fit for our models and cross validation strongly support our modeling results for all months. Differences in model selection reported here can aid water managers in decision making for water availability, food security and economic growth.