Sources analysis the of urban non-point source pollution in in two typical towns of hill and plain in the Yangtze River Basin
In the hilly urban area of Yongchuan District,Chongqing,and the plain urban area of Jintan District,Changzhou,both situated in the Yangtze River Basin,four areas with two drainage systems(namely,combined system and separate system)were selected as study objects.Quality data of rivers,riverine outfalls,and surface runoff in these areas were systematically monitored during rainy days.The study employed the river mass conservation method to assess the contributions of non-point source(NPS)to river pollution;employed the PMF model to trace the pollution sources to riverine outfall;and employed the surface runoff mass conservation method to analysis the pollution sources to surface runoff.The results showed that:Urban NPS contributed to the five water quality indicators(SS,COD,NH3-N,TN and TP)in the rivers in the four study areas to a certain extent,and the specific contribution rates were related to the rainfall levels,regional characteristics and drainage regimes;During rainfall events in both types of towns,surface runoff was identified as the primary source of SS and COD loads at the riverine outfalls.On the other hand,NH3-N,TN,and TP loads were predominantly contributed by sanitary sewage and sewer sediments at these outfalls in the two different drainage regimes;Influenced by factors such as topographic slope and population density,the main pollutant-producing surfaces of Yongchuan and Jintan were different,with Yongchuan being neighborhood roads and Jintan being traffic roads and roofs.Targeted control measures were proposed to improve the refined management of urban NPS pollution in the above study area.
hill urbanplain urbanurban non-point sourcemass conservation methodPMF model
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