Infiltration Study & Native Priaire Grass Restoration at Johnson County Transit Center

Researchers from Kansas State University, in partnership with the Johnson County Stormwater Management Program, are studying the effects of storm water runoff at the Johnson County Transit Center. Infiltration occurs when rain falls and a portion of the water is absorbed into the ground. Rainwater which is not absorbed is referred to as “runoff.” Runoff travels over the ground and enters the storm sewer system carrying pollutants picked up from the land surface directly to our streams untreated. Ideally, most rainfall would be infiltrated into the ground. Storm water infiltration can lead to cleaner streams and rivers, because stormwater is filtered and the majority of pollutants are removed as it percolates through the soil. Infiltration is severely limited in urban and suburban environments due to the large amount of impervious surface such as pavement and rooftops. Problems caused by runoff include flooding, pollution of streams and lakes as well as stream bank and soil erosion. Two common pollutants carried by runoff are sediment and nutrients, which are primary non-point source pollutants of our streams and lakes.

The goals of the project are:

1. Determine the current runoff conditions, how much runoff is currently produced from the project area and what the runoff contains (i.e. how much sediment and nutrients?)
2. Reduce runoff by increasing rainwater infiltration. Native prairie grass landscapes allow much more infiltration of rainfall than typical turf grass lawns. Native prairie plants are not mown, so each blade and leaf can hold much more rain water on its surface. Native prairie plants have deep root systems that aerate the soil, creating many tiny pockets for storing rainwater.
3. By replacing the existing landscape (mostly turf grass) with a mixture of native grasses and forbs, rainwater infiltration will increase while reducing runoff. The landscape of native plants will be monitored to determine the amount of rainwater infiltration and the amount and quality of runoff.

Here's a before shot of our front lawn.

The project began in the summer of 2007 with plowing & re-seeding

One month after seeding.

The same rocks and plantings after two months.

Fall of year one mowing, to reduce weeds before the winter.

July 2008, one year later. You see a lot of weeds, but a lot of strong undergrowth taking root.

The decision was made to mow to control the weed growth.

One month later, August 2008, all the growth is back.

Sept 2009, after year 2. Lots of weeds. This is to be expected. It takes 5 years for native prairie to take a firm hold. The prairie grass is doing well. Weeds always jump out first in any new project. 2010 should be a productive year with a burn-off proposed.