An innovative approach based on water environmental capacity for non-point source NPS pollution removal rate estimation was discussed by using both univariate and multivariate data analysis.Taking Shenzhen city as the study case a 67% to 74% NPS pollutant load removal rate can lead to meeting the chemical oxygen demand COD pollution control target for most watersheds.In contrast it is hardly to achieve the ammonia nitrogen NH4-N total phosphorus TP and biological oxygen demand BOD5 pollution control target by simply removing NPS pollutants. This highlights that the pollution control strategies should be taken according to different pollutant species and sources in different watersheds rather than one-size-fits-all .
In order to have an in-depth understanding of road runoff characteristics and the linkages to their influential factors this paper investigates the road runoff quality in a city of South China Shenzhen.Four rainfall events with different characteristics are monitored on a typical urban road.It is noted that the road runoff quality is worse than Grade Ⅳ of environmental quality standards for surface water.This means that the road runoff has posed a serious risk to water environment health. Furthermore the research outcomes indicate that first flush highly varies with rainfall patterns and pollutant species.This means that for road runoff treatment design rainfall patterns as well as pollutant species should be taken into consideration and this is particularly essential to design first flush capturing devices. Additionally the threshold of an initial 3 to 5 mm rainfall depth is suggested to the first flush capturing device design.These results provide useful suggestions to the effective road runoff treatment design.
