降雨径流过程对不透水面空间分布的响应解析

Response analysis of rainfall runoff processes to spatial distribution of impervious area

【目的】城市化导致城市下垫面空间特征复杂化,其中显著特征是不透水面与透水面之间形成复杂的空间关系,对城市地表径流过程产生一定影响。进一步探索降雨径流过程对不透水面空间分布的响应机理,有利于深化城市水文效应科学认知。【方法】开展了降雨径流试验,基于试验数据对二维水动力模型参数进行了率定和验证,并基于所得参数构建了区域大小为1 km×1 km的降雨径流模型,开展了3场真实降雨情景和4类(不透水面上、中、下游和随机分布)城市不透水面空间分布情景下的地表径流过程模拟,对不同情景下的地表径流过程和径流特征进行了分析。【结果】结果表明:在降雨情景A(降雨量10.0 mm)和20%不透水率情景下,上游分布和随机分布之间的径流系数差值占比最大,可达59.9%;在降雨情景B下(降雨量51.8 mm),最大径流流量差值占比为67%。【结论】在同一不透水率下,不透水面空间分布对地表径流过程和径流特征值有一定影响,其影响程度通常随着降雨强度的增加而减小;在同一降雨和不透水率下,在设置的4类不透水面空间分布情景中,不透水面随机分布对径流过程的影响相对其他分布较大。研究结果可为城市径流管控与洪涝防治提供一定参考。

[Objective]Urbanization leads to complex spatial feature of urban underlying surface,in which the significant feature is the formation of complex spatial relationship between impervious surfaces and permeable area,which has some impact on the urban surface runoff process.Further exploration of the response mechanism of rainfall-runoff processes to impervious surface spatial distribution is conducive to scientific understanding of urban hydrological effects.[Methods]We conducted rainfall-runoff laboratory experiments,calibrated and validated the parameters of the two-dimensional hydrodynamic model based on experimental data,a rainfall-runoff model with an area size of 1 km×1 km based on the two-dimensional hydrodynamic method was constructed,based on the validated parameters.Simulations of runoff processes in three real rainfall scenarios and four types of urban impervious surface spatial distribution scenarios(upstream,midstream,downstream,and randomly distributed)are conducted,the surface runoff processes and characteristics under different scenarios are analyzed.[Results]The result show that,the difference in runoff coefficients between the upstream distribution and random distribution accounts for the largest difference ratio,up to 59.9%,under the scenarios of rainfall A(rainfall 10.0 mm)and 20%imperviousness.Under rainfall scenario B(rainfall 51.8 mm),the maximum runoff flow difference is 67%.[Conclusion]Under the same imperviousness rate,the spatial distribution of impervious area has some influence on the runoff process and runoff characteristics,and the impact rate usually decreases with the increase of rainfall intensity.Under the same rainfall and imperviousness rate,among the four spatial distribution scenarios of impervious area set in this study,the random distribution of impervious area has a relatively greater impact on the runoff process compared to other distributions.The result of the study may provide some reference for urban runoff control and urban flood prevention.