Eastern SD Getting Wetter Over Past 65 Years

Dec 16, 2015

Flooding in June of 2014 inundates the Liberty School in the Eastern, SD town of Harrisburg.
Credit Jim Holbeck

Is your old cornfield a new bass pond?  There are now parts of eastern South Dakota where the fishing is better than the farming.

A new study by the United States Geological Survey shows a trend towards a wetter climate east of the Missouri River over the last six and a half decades.  Stream gages along waterways like the James and Big Sioux Rivers show a general pattern of increased rains and river flows since 1948. Researchers say they hope this data can be used by ag producers, land managers, and emergency management personnel as they plan for the future.

 

Galen Hoogestraat is a Hydrologist with the United States Geological Survey. He’s examined the stream flow and rainfall data in Eastern South Dakota over the last six and a half decades.  The study includes measurements taken over this time on fixed points along the James and the Big Sioux Rivers.

“It’s sort of a different ballgame.  There is a new normal.  We show some examples where the streamflow along the James or the Big Sioux with 20 or 25 inches of rain you get twice as much flow as you did back in the ‘50’s or ‘60’s,” says Hoogestraat.   

In 2014 the Big Sioux saw historic flooding causing millions of dollars in damage.   Hoogestraat says this study, showing an increasing trend of rainfall and runoff, could be of use to public officials and even emergency managers.

There is a new normal.

“In some cases you may even see that with updates to flood maps, you’re taking about these FEMA flood maps updates that always come out when those get revised often those incorporate new information, so you know that were seeing wetter conditions that includes more areas that are prone to flood,” says Hoogestraat.  

The USGS study also examined any role changing land use practices, like drain tiles, could play in increased runoff.   The data shows that higher stream flows are generally due to the trend towards a wetter climate in Eastern South Dakota.