Effects of Land Use and Rainfall Characteristics on River Pollutions: A Case Study of Xili Reservoir Watershed in Shenzhen, China

摘要

The restoration of polluted rivers is important to protect reservoir water sources. Heavy metal and nutrient pollutions of river selected in the Xili Reservoir Watershed were investigated with different land use and rainfall characteristics. Stormwater runoff was the main contributor of river pollution loads: Ba 68%, Pb 96%, Cr 64%, Al 60%, Fe 58%, Mn 32%, Cu 46%, Zn 78%, TN 25%, and TP 48%. Commercial land use contributed 53~80% of heavy metal loads and industrial land use was also an important source of heavy metals especially for Ba, Pb, and Cu. Nutrient loads showed different trend: commercial > residential > industrial because of eating residues generated in densely populated area. River pollution was affected by rainfall intensity and rainfall duration greatly. Strong rainfall events could wash more road deposited solids or sewer sediment into the river and the import of runoff could cause the resuspension of the river sediment. Hence, the restoration of polluted rivers should adopt comprehensive strategies of reducing the outer pollutions (e.g., stormwater runoff and sewer sediment) and cleaning the river sediment.