城市圩区水环境多因素影响研究

Research on the Influence of Multiple Factors on Water Environment in Urban Polder Areas

城市圩区河道一般自然流动性差、自净能力低,普遍存在水环境恶化问题。研究区东亭街道属于无锡市运东大包围内的圩中圩,具备城市圩区的一般特征,且生活污染排放量大,主要污染因子为氨氮。通过MIKE 11模型,以氨氮为控制目标,着眼于研究区内部控源截污水平、研究区外围水体水质和畅流活水3种因素,模拟分析在改善其中1个或多个因素时的氨氮浓度削减率,评价3因素对研究区水环境的影响比重。结果显示,3因素中外围水质对研究区水环境的影响最大,当外围水质提升至Ⅳ类时,氨氮削减率为67.3%;其次,当内部截污水平提高至98%时,氨氮削减率为53.6%;最后为畅流活水手段(Ⅳ类水水源6 m^3/s),氨氮削减率为50.3%。当同时改善2个及以上因素时对水环境改善具有叠加作用,最高可使氨氮浓度削减85.5%左右。

Rivers in urban polder areas generally have poor natural fluidity and low self-purification capacity,so the water environment deterioration is a common problem in these areas.Dongting Street,belonging to Wuxi,is a diked area in the Yundong Polder.It has the general characteristics of the urban polder areas.Dongting Street has a large amount of domestic sewage discharge,suggesting the main pollution factor is ammonia nitrogen.This research uses the MIKE 11 model intended to control the concentration of ammonia nitrogen.By using the MIKE 11 model,this research analyzes the reduction rate of the concentration of ammonia nitrogen under the condition that one or more of the three factors improved.Results suggest that the peripheral water quality has the greatest impact on the water environment at the studied area.When the peripheral water quality was improved to classⅣsurface water standard of China(GB3838-2002),the reduction rate of ammonia nitrogen was 67.3%.The reduction rate was 53.6%when the pollution level increased to 98%.At last,when theⅣwater source(6 m^3/s)was input through gate and pump station,the reduction rate was 50.3%.When two or more factors were simultaneously improved,there was a superposition effect on the improvement of water environment,and the ammonia nitrogen concentration reduced by about 85.5%at most.