What are the primary reasons for the urban effects on the hydrological cycle?
Urban land uses are marked with impermeable land cover elements such as roofs, roads, sidewalks, and parking lots, resulting in more runoff and negligible infiltration. The conversion of pervious land cover to impervious surface results in increases in the rate of volume of storm runoff and reductions in groundwater recharge. Discharge of runoff waters directly to watercourses may adversely affect the quality of the receiving water body. For example, a range of organic and inorganic pollutants as well as heavy metals may be carried from road surfaces. In urban areas, collection in combined sewerage systems may impose increased hydraulic and pollutant loads on conventional wastewater treatment facilities (Perry and McIntyre 1986). Areas where urban infiltration can occur include lawns, parks, and golf courses. These land uses are often associated with practices that utilize fertilizers and chemicals, thus increasing the potential for groundwater contamination.
