     
|
Slow Storm Water Runoff and Encourage Infiltration
Minimizing Impacts at the Local or Site Level
Development in watershed result in increase of impervious area which result in a related increase in runoff generated during rain events. The figure shows how the percentage of runoff reaching streams and other water bodies varies with change in land use.
Storm water basins and constructed wetlands reduce the risk of increased flooding due to increase in storm water runoff. These basins retain storm water and release it over a period of time. Storm water basins are important for reducing peak flows, but they do not solve the problem of increased runoff due to development. Storm water basins can be designed to be aesthetically pleasing and can potentially be used as recreational facilities on a site. They can also be used for economic benefit by developers and realtors as many people enjoy living near water and are willing to pay higher prices for such plots.
Temporarily storing water is a frequently used infiltration control measure. Increased infiltration is achieved by creating infiltration trenches and basins designed to store water temporarily. This gives the water more time to infiltrate into the ground. Using porous and grid pavements in construction also increases infiltration. Dry wells, exfiltration filters, level spreaders are other techniques that can be used to increase infiltration. For further details refer to Nighman (1999). Existing landscape areas in parking lots can be used for onsite stormwater management and for retention of water to allow it to percolate through instead of becoming runoff. Runoff can be directed into a shallow, landscaped area and temporarily retained. Such bioretention facilities can be attractively integrated into the landscaped area and can be maintained by commercial or other firms in “adoption” schemes.
Details on use of constructed wetlands for reduction of runoff and non point source pollutants can be found at the following site http://enviro.nfesc.navy.mil.
