水力演算方法对SWMM模型排放口出流的影响

Influence of Routing Methods on Outflow of SWMM Model

分析了恒定流、运动波和动态波3种演算方法的原理,并以西安某居民小区为研究对象,建立SWMM模型,通过使用实测降雨数据对该模型进行了参数率定。设计4种不同重现期的降雨,分别使用3种演算方法得到排放口的出流过程线,再比较长历时下不同演算方法的运算时间。结果表明:恒定流可用于简单、低精度的模拟,对低重现期或长历时的连续模拟,初期的分析具有一定的参考价值;运动波的短历时模拟结果比恒定流更精确,但此方法也不适用于大重现期降雨的模拟,如果不要求模拟精度高,尤其是对长时间序列的模拟,设置较大的步长,初期的模拟具有很好的参考价值;动态波在低重现期下的精度略高于其他两种演算方法,但在高重现期降雨情况下动态波具有绝对的精度优势,应首选动态波法。

The principles of steady flow, kinematic wave and dynamic wave were analyzed. A SWMM model was built for a residential area in Xi＇ an. The parameters of the model were calibrated to the measured rainfall and runoff data. Discharge hydrographs were calculated for four different return pe riods of rainfall using three routing methods. The computation time of the routing methods were compared for long rainfall duration. Results indicated that the steady flow method was suitable for simple and low precision simulations, and it provided insights to simulations of low return periods or long simulation periods. The kinematic wave method had more accurate simulation result for short rainfall duration than the steady flow, but it also was not suitable for simulation of heavy rainfall events. However, if high simulation precision was not required, especially for a long simulation period, the method could provide a more stable result. The precision of dynamic wave method in low return period was slightly higher than those of the other two methods. When simulating a large return period rainfall event, dynamic wave had absolute advantages regarding the modelling precision and should be the top choice.