Low impact development (LID) systems and practices use or mimic natural processes that result in the infiltration, evapotranspiration or use of stormwater in order to protect water quality and associated aquatic habitat. The approach emphasizes use of bioretention facilities, constructed wetlands and other land development principles that minimize imperviousness and recreate landscape features in order to treat stormwater as a resource instead of a waste product. Field research conducted in Yuelai, Chongqing, China examined the influence of LID on urban stormwater quality at the catchment scale.

Stormwater samples collected at sites incorporating different underlying surfaces reflective of highway, commercial, residential and green park land uses were assayed for pH, suspended solids, chemical oxygen LID practices enhance infiltration, evapotranspiration or use of stormwater in order to protect water quality and aquatic habitat. Source: Zheng Kong et al.demand, total nitrogen and total phosphorus. The results published in the Journal of Cleaner Production confirm that LID practices purified stormwater runoff and decreased urban non-point source pollution significantly.

Pollutant load was markedly reduced at the catchment scale to the benefit of receiving water quality. The residential area contributed the smallest proportion of total pollutant load while highway and commercial areas contributed most of the total nitrogen load. LID construction was also observed to reduce stormwater runoff pollutant event mean concentrations and first flush effects. Stormwater treated after exposure to green infrastructure systems was qualified for road cleaning and landscaping.

Scientists from Chongqing University, Southwest University, Chongqing Yuelai Investment Group Co. and Chongqing Green Environmental Protection Technology Co. contributed to this research.