长江流域丘陵与平原城镇降雨径流污染特征对比分析

Comparative analysis of rainfall runoff pollution characteristics between hilly and plain towns in the Yangtze River Basin

随着城市化进程的加速,长江流域降雨径流导致的城镇面源污染问题日益凸显。在长江流域丘陵城镇重庆永川区和平原城镇常州金坛区分别选取部分老城区和部分新城区作为研究区域,监测4个研究区域降雨径流的水质和水量,采用场次降雨径流平均浓度(EMC)和综合径流系数法计算各下垫面降雨径流污染物平均浓度和污染负荷,采用b(初期冲刷系数)参数法分析降雨径流初期冲刷效应。结果表明:1)SS、COD、TP、NH3-N和TN的EMC主要受地形、降雨特征及前期干旱天数影响,丘陵城镇中交通道路SS和COD的EMC分别是其他下垫面的1.10~7.05和0.86~8.98倍,平原城镇中交通道路SS和COD的EMC分别是其他下垫面的1.01~3.70和1.07~6.70倍;2)丘陵城镇降雨径流初期冲刷效应强于平原城镇,且SS和COD的初期冲刷强度较高,b的范围分别为0.25~1.20和0.50~1.28;3)丘陵城镇各下垫面污染负荷平均输出系数大于平原城镇,丘陵城镇老城区各指标污染负荷平均输出系数为平原城镇的0.37~16.13倍,丘陵城镇新城区各指标污染负荷平均输出系数为平原城镇新城区的0.38~7.11倍。研究揭示了长江流域丘陵和平原城镇降雨径流污染特征,可为这两类城镇降雨径流污染控制提供参考。

With the acceleration of urbanization,the problem of urban non-point source pollution caused by rainfall runoff in the Yangtze River basin has become increasingly prominent.Some old and new urban areas were selected as the research objects in the hilly towns of Yongchuan District in Chongqing City and the plain towns of Jintan District in Changzhou City in the Yangtze River basin.The water quality and quantity of rainfall runoff in the four research areas were monitored.The event mean concentrations (EMC) and comprehensive runoff coefficient methods were used to calculate the average concentration and pollution load of rainfall-runoff pollutants on each underlying surface.The b-parameter method was used to analyze the first flushing effect of rainfall runoff.The results showed that:(1) The EMC of SS,COD,TP,NH3-N and TN was mainly affected by topography,rainfall characteristics and early drought days.The EMC of SS and COD in traffic roads in hilly towns was 1.10-7.05 times and 0.86-8.98 times that of other underlying surfaces,respectively.The EMC of SS and COD in traffic roads in plain towns was 1.01-3.70 and 1.07-6.70 times that of other underlying surfaces,respectively.(2) The first flushing effect of rainfall runoff in hilly towns was stronger than that in plain ones,and the first flushing intensity of SS and COD was higher,with b values ranging from 0.25 to 1.20 and 0.50 to 1.28,respectively.(3) The average outpu coefficient of the pollution load of each underlying surface in hilly towns was greater than that in plain ones.The average output coefficient of the pollution load of each index in the old urban area of hilly towns was 0.37-16.13times that in plain towns,and the average output coefficient of the pollution load of each index in the new urban area of hilly towns was 0.38-7.11 times that in plain towns.The study reveals the characteristics of rainfall-runoff pollution in hilly and plain towns in the Yangtze River basin,which can provide reference for the control of rainfallrunoff pollution in these two types of towns.