Analysis of urban runoff pollution and the improvement effect of LID on runoff quality

With the acceleration of urbanization, more and more attention has been paid to the rainfall runoff quality. A study on the relationship between rainwater runoff water quality and land use type was conducted in the Tianhe Wisdom City, a typical urban area in Guangzhou, China. Runoff samples from roof, road, green space and permeable pavement were collected and the pollutants were detected and analyzed. The correlations of different pollutants from different land use types were indicated by using principal component analysis (PCA). The first flush effect was determined and quantitative analyzed by mass first flush ratio (MFF_n). And then the effect of low impact development (LID) on the first flush was discussed based on Storm Water Management Model (SWMM). The results show that the strength of first flush is stronger in the impervious areas and nitrogen and phosphorus were the main pollutants. The MFF_n decreases after setting LID, which indicates that the implementation of the LID is beneficial to reduce the strength of first flush effect. Therefore, the LID can improve the water quality of urban stormwater runoff. The results can be used as a reference for stormwater runoff quality management for cities.