城市低影响开发对雨水径流氮污染物的控制效应—以宁波海绵城市试点区域为例

为定量评估城市低影响开发的环境效应, 以宁波海绵城市建设试点区为例, 通过构建研究区SWMM模型, 研究不同降雨强度下16种低影响开发情景方案对雨水径流量、氨氮(NH3-N)、硝态氮(NO3-N)和总氮(TN)等氮污染物控制的效应. 结果表明, 生物滞留池、透水铺装单项技术及其组合方案对雨水径流量的削减率分别介于3.41%~41.83%、1.08%~27.77%和5.59%~51.13%; 低影响开发对各种氮污染物的削减作用与降雨强度、设施种类及面积有关, 生物滞留池对径流量和氮污染物的控制效应强于透水铺装; 在小降雨事件(<)中, 低影响开发技术对NH3-N、NO3-N和TN均具有较高的控制效率, 当降雨强度增大时控制效率较低, 但污染物的削减总量较大; 当研究区海绵设施面积为2时, NH3-N、NO3-N和TN的污染负荷削减率分别高于28.62%、32.42%和24.82%.

Control effects of low impact development in urban area on rainwater nitrogen pollution: Case study of the pilot area of sponge city construction in Ningbo

To evaluate the environmental effects of the approaches of low impact development on the rainwater runoff volume and pollution loads of ammonia nitrogen (NH3-N), nitrate nitrogen (NO3-N), and total nitrogen (TN), a SWMM model is developed for the sponge city construction pilot area of Ningbo, China. After model calibration and validation, the impacts of 16 alternative management strategies are studied under different rainfall intensity. The results show that the reduction rates of rainwater runoff volume for the four scenarios of bio-retention facilities, four scenarios of permeable pavements, and eight scenarios of the combination of bio-retention and permeable pavements are in the range of 3.41%–41.83%, 1.08%–27.77%, and 5.59%–51.13%, respectively. The unit-area pollution loads of the selected nitrogen pollutants and their reductions caused by low impact development are related to the area of the facilities and rainfall intensity. The reduction effects of bio-retention facilities on the runoff volume and the pollution loads is slightly stronger than that of the permeable pavements. Under the light rainfall event of lower than , low impact development could result in high reduction rates for various nitrogen pollutants. When the rainfall intensity increases, the reduction rates of runoff volume and unit-area pollution loads decrease. Nevertheless, the reduction amount of pollutants during the rainfall events turns out to be still large. If the area of low impact development in the pilot area of sponge city construction in Ningbo covers 2, the pollution loads of NH3-N, NO3-N, and TN can be reduced by higher than 28.62%, 32.42%, and 24.82%, respectively, comparing with those before the commencement of the project.