So far, the management of water pollution has been focused mainly on the post-treatment of point pollutions such as urban sewage and industrial waste water. Considerable improvement has been made to the water quality and the reduction of pollution. However, this post-treatment oriented policy has no countermeasures for non-point pollution that occupies considerable portion of water pollution. Moreover, increased impermeable rate accompanied by urbanization changed the characteristics of storm runoff. It added to the damage from flood due to rapid storm runoff seen from the water volume aspect. Seen from the aspect of water quality, it caused the water quality to be deteriorated with the runoff of various polluting materials into the water system along with the storm runoff. Therefore, immediate action shall be taken to properly control the storm runoff to reduce the risk of flood by rapid storm runoff and to improve the water quality.
The review on the runoff characteristics of non-point pollution materials by storm runoff showed that BOD, CDO, SS, T-N and T-P featured the first-flushing effect, showing relatively high concentration in early-stage storm runoff, however, the heavy metal(Zn, Cd, Pb, Cu) showed no meaningful significance with the first-flushing effect and storm runoff tendency. Another review on the Site Mean Concentration(SMC) of non-point pollution materials according to the use of land revealed that the SMC of BOD was in relatively low concentration in the range of 5.3～12.1mg/L, no meaningful significance by the use of land. The SMC of COD and SS range