Ravine Stabilization

Shabica & Associates, Inc.

Sustainable Coastal Solutions

Lake Bluff ravine before restoration

Ravine Stabilization

Ravines are natural drainage valleys that were cut into the earth after the glaciers melted 10,500 years ago. Today, ravines still function as natural drainage for surface runoff. However, wooded ravines that have been stable for thousands of years have, in the last 100 years, undergone loss of natural streambed armor, active streambed downcutting and bank erosion. Increased urbanization has contributed to this problem by creating higher levels of stormwater runoff due to municipal sewers and impermeable surfaces such as roads, parking lots, driveways and roofs. In Illinois, ravines are a conduit for stormwater runoff into Lake Michigan.

Shabica & Associates has found that the most cost-effective and environmentally-sensitive method to restore a ravine streambed and bank is to repave it with natural stone cobbles. Engineering is necessary to determine the stone size, quantity and placement.

Research conducted by Shabica & Associates on ravine preservation has received high acclaim by public agencies such as the Great Lakes Commission.

Two years after restoration

Natural stone and native vegetation have helped to reduce the stormwater velocity and damage to the streambed.

Ravine: a narrow steep-sided valley commonly eroded by running water

Typical Native Ravine Streambed

Excess urban stormwater velocity has downcut the ravine and “blown out” all of the natural stone streambed armor.