Hobbies And Interests
Urbanization
On a natural tract of land, around 10 percent of the rain falling in the area runs off the land into rivers, streams and lakes. The remaining 90 percent evaporates into the air or soaks into the ground. The more developed an area, the more stormwater becomes an issue. Man-made surfaces are frequently impermeable and lead to an increase in the volume and rate of stormwater runoff. Such drastic changes to an area's hydrology increase the frequency and severity of flooding. Rectifying damage to public and private property caused by uncontrolled stormwater runoff costs local governments millions of dollars every year
Water Quality
Stormwater either runs into natural waterways directly or is taken there, untreated, via storm sewers. As it travels through urban areas, stormwater collects a variety of pollutants such as the sediment from construction sites; nutrients from septic tanks and fertilized garden lawns; bacteria from leaking sewers and pet waste; oil from industrial areas and badly maintained cars; trace metals from industrial areas; road salt to prevent icing; and a range of chemicals from industrial processes. These pollutants all damage the sensitive ecology of oceans, lakes, streams and rivers.
Regulations
Stormwater management uses the Federal Clean Water Act as its primary basis. The Act seeks to make all U.S. waters safe for activities such as fishing and swimming. The Environmental Protection Agency (EPA) and other agencies also set standards and provide assistance with federal water quality programs. The EPA considers the majority of stormwater discharges as point sources of pollution and requires them to be covered by a National Pollutant Discharge Elimination System permit.
Systems
Many urban developments were based on the 19th century idea of hygenism. This states that the goal of urban drainage systems is to remove sewage and stormwater as quickly as possible from urban areas so that the risks of flooding and contagious water-borne diseases are reduced. To do this, underground systems were used so that disposal did not restrict urban development. Although separate sewer systems are used to drain sewage and stormwater, damage to the pipelines can lead to cross contamination. Modern approaches to stormwater management include the use of holding tanks in new developments. These tanks collect stormwater, which is then released at a reduced rate to drainage networks or watercourses.