Science Source

Are climatic or land cover changes the dominant cause of runoff trends in the Upper Mississippi River Basin?

States that the Upper Mississippi River Basin (UMRB) has experienced a remarkable agricultural extensification since the mid‐1800s
Hydroclimatological monitoring in the 20th century also reveals positive annual precipitation and runoff trends in the UMRB
States that while several studies have proposed land use/land cover (LULC) change as the primary cause of runoff increase, little is known about the dominant controls of hydrologic change in the UMRB
Uses a macroscale hydrology model to assess the hydrologic implications of climate and LULC changes between 1918 and 2007
Modeling results, corroborated with hydroclimatologic data analysis, emphasized climate change as the dominant driver of runoff change in the UMRB
Finds that, at local scales, modeled annual runoff decreased (increased) by up to 9% (5%) where grasslands (forests) were replaced by croplands
Finds that artificial field drainage amplified annual runoff by as much as 13%
Concludes that these findings are critical for water and nitrogen management in the UMRB under change