平原湖区外江水位变化对排涝流量的影响

为准确模拟排区涝水产汇流过程及水量,以湖北省四湖流域螺山排区为例,通过耦合SCS和MIKE11模型来建立排区尺度的涝水产汇流模型,分别采用1980年、1983年和1991年、1996年螺山泵站站前的实测水位数据对模型进行率定和验证,并通过设置不同设计暴雨和外江水位的组合,以评估外江水位变化对排涝流量的影响。结果表明:率定期1980年和1983年模拟水位和实测水位的相对误差分别为-0.20%和-0.40%,相关系数分别为0.980和0.952,效率系数分别为0.949和0.849;验证期1991年和1996年模拟水位和实测水位的相对误差分别为-0.10%和1.70%,相关系数分别为0.919和0.967,效率系数分别为0.782和0.906,表明耦合模型模拟效果较好,适用于螺山排区产汇流模拟。根据5年一遇、10年一遇3日暴雨与5年一遇、10年一遇汛期最高5日平均水位、泵站设计外江水位组合下排涝流量的模拟可知,在相同的设计暴雨下,外江水位越高,泵站的抽排流量越小,并且对内涝造成的不利影响越大。如按排涝泵站水泵的性能曲线进行模拟,精度将提高19.6%~53.8%。

Influence of outer river flood level on drainage discharge in plain lake areas

The accurate simulation of the process of runoff yield and concentration in the drainage area is of important significance for the reasonable determination of the scale of drainage projects and their orderly operation.The Luoshan drainage area in Four-lake Watershed in Hubei Province was selected as the research area.The runoff yield and concentration model at a drainage area scale was developed by coupling SCS with MIKE11.The coupled model was calibrated with the measured water level of Luoshan pumping station in 1980 and 1983, and validated with the measured water level in 1991 and 1996.Results showed that the relative errors between simulated and measured water levels were -0.20% and -0.40% respectively, the correlation coefficients were 0.980 and 0.952, and the efficiency coefficients were 0.949 and 0.849 respectively during the calibration periods (1980 and 1983).The relative errors between simulated and measured water levels were -0.10% and 1.70% respectively, the correlation coefficients were 0.919 and 0.967, and the efficiency coefficients were 0.782 and 0.906 respectively during the validation periods (1991 and 1996).Good agreements between simulated and measured water levels indicated that the coupled model was appropriate to simulate the process of runoff yield and concentration in the drainage area.Then the coupled model was used to analyze the influence of flood levels of the outer river on drainage discharge with six scenarios, which were combinations of two design storms with three flood levels of the outer river.Two design storms, 175.57 mm and 212.07 mm, were corresponding to three-day storms with return periods of 5 years and 10 years respectively.And three flood levels of the outer river, 32.63 m, 33.45 m and 30.68 m, were corresponding to the maximum five-day mean water levels in flood season with return periods of 5 years and 10 years, and the design level of the outer river of the pumping station.The simulation results showed that for the same storm, the higher flood level of the outer river was, the larger the required pumping drainage discharge was, and vice versa.Furthermore, the adverse influence of the flood level of the outer river on drainage was greater with the rising of flood level of the outer river.If the drainage discharge was simulated according to the pump characteristic curve, the simulation accuracy of drainage discharge could be improved between 19.6% and 53.8%.The coupled model could be applied as a useful tool for the accurate determination of the capacity of drainage pumping stations in this drainage area which was affected by the flood level of the outer river.