基于SWMM的中尺度雨水系统构建下的水质水量模拟

以构建适用于中尺度雨水系统为目标,以江西省南昌市某廉租房区(面积为2 hm2左右)为研究区域,根据实地监测和踏勘资料,在原有雨水系统的基础上,分别构建简易式和断接式中尺度雨水系统的SWMM模型,分析地面径流情况,并以TSS、TP、TN、CODcr四种污染物,模拟污染物随径流扩散的过程。结果表明:较于3年重现期下的传统开发,简易式能达到5年重现期不积水,并且随重现期的增大,地表径流的削减率越来越小;断接式不仅能保证10年不积水,径流削减的变化趋势与简易式一致,并且削减情况优于简易式,能更长时间的延缓径流峰值的出现。污染物浓度随重现期增大,前期逐渐增大,中期出现峰值,后期逐渐减小,冲刷效果也逐渐明显,且两者的污染物削减效果相较于传统开发,均能达50%以上;但是在高重现期下,无论是水质还是水文的模拟表明,由于土壤达到饱和,两者作用效果不相上下。总得来说,采用断接式能更好地控制径流量和径流污染物。

SWMM-based simulation on water quality and water quantity for construction of mesoscale rainwater system

In order to construct the mesoscale rain system，the SWMM models for the rainwater systems of both the simple type and the disconnection type are respectively established in accordance with the relevant in situ monitoring and investigation data on the basis of the original rainwater systems concerned by taking a low-rent housing residential sub-district (about 2 hm2 ) in Nanchang of Jiangxi Province as the study area，and then the surface runoff therein is analyzed，while the process of pollutant-diffusion along with runoff is simulated based on the four kinds of pollutants，i. e. TSS，TP，TN and CODcr. The result shows that compared with the conventional development under the condition of a return-period of three years，the simple type of rainwater system can reach the target of no water-logging within a period of five years，while the reducing rate of the surface runoff is to be smaller and smaller along with the increase of the return-period. Meanwhile，the disconnection type of rainwater system cannot only ensure that no water-logging occurs within a period of ten years and the changing trend of runoff reduction accords with that of the simple type as well as the runoff reduction is better than that of the simple type，but can also delay the occurrence of the runoff peak for a much longer time. Along with the increase of the return-period，the concentration of pollutant gradually increases in the earlier-phase，peaks in the meta-phase and gradually decreases in the later-phase with more and more obvious scouring effect. Compared with the conventional development，the pollutant reducing effects of the both types of rainwater system can reach to over 50% . However，no matter whether the simulation of water quality or the hydrological simulation，it is indicated that due to the saturation of soil，the effects of both of the rainwater systems are basically the same under the condition of a high return-period，but the disconnection type of rainwater system can generally control the flowrate of runoff and the runoff pollutants much better.