The topography (lay of the land) of an area's watershed can have a lot to do with how water resources are affected by development. Large-scale development means that a lot of land clearing and grading occurs. If the area has sloping land, soils that erode easily, and receives frequent periods of heavy rainfall, then water quality can be affected, usually in a negative way.
Eroded soil from construction sites is carried to streams and lakes where it causes (1) excess turbidity that harms aquatic life, increases water-treatment costs, and makes the water less useful for recreation; and (2) sedimentation that clogs drainage ditches, stream channels, water intakes, and reservoirs, and destroys aquatic habitats.
Erosion and sedimentation controls include a wide range of temporary
and permanent measures. Planting vegetation is one of the best ways
to stabilize soils and minimize erosion.
Sedimentation ponds
are used to capture storm runoff and allow sediment to settle to the
pond's bottom, and silt fences
are used to contain water runoff and minimize sedimentation in
nearby streams. As the picture to the right shows, silt fences do not always work.
As this picture shows, without proper design, installation, and
maintenance of erosion and sedimentation controls, sediment-laden
runoff from construction sites can damage streams and nearby
properties. In this case, a tributary draining a construction site
is depositing sediment-laden water into the clearer river at the top.
U.S. Department of the Interior | U.S. Geological Survey
URL: http://ga.water.usgs.gov/edu/urbansed.html
Page Contact Information: Howard Perlman
Page Last Modified: Friday, 07-Nov-2008 15:46:39 EST
