基于城市下垫面精细化分类的降雨径流关联性研究

    Correlation between rainfall and runoff based on refined classification of urban underlying surface

    • 摘要: 现有城市排水规划一般采用恒定径流系数估算城市径流,在降雨特征复杂、下垫面种类多样的情况下,单一径流系数估算难以满足日益精细化管理的需求。因此,以下垫面复杂的上海城市区域为研究对象,根据遥感影像精细化分类11种下垫面,现场动态监测降雨径流,分析下垫面径流特征,并基于SWMM模型确定水文参数,探明区域径流、渗流与降雨因子的关联性。结果表明:①与不透水下垫面相比,透水下垫面在短历时、高强度前锋型降雨下初始产流量减少6.4~15.7 mm,在长历时、多峰值降雨下产流时间滞后3.5~23.8 h,植被截留和土壤渗透作用能有效削减初始产流量或滞后产流时间、径流峰值时间;② 8种不透水下垫面径流系数大小为水泥屋顶>机动车路面>室外停车场>广场路面>单位路面>瓦面屋顶>居住小区路面>人行道,曼宁系数和洼蓄量分别为0.012~0.021和2.71~3.91 mm;③ 3种透水下垫面径流系数大小为草地>灌木地>林地,曼宁系数和洼蓄量分别为0.27~0.41和4.16~5.32 mm;④ 15场降雨下区域径流系数为0.58~0.89,其中高强度暴雨、大暴雨或特大暴雨下径流系数为0.76~0.89;⑤区域径流量与降雨量呈正向线性关系(R2=0.995),下渗量与降雨量呈较好的对数关系(R2=0.955)。研究成果可为径流源头控制、排水系统溢流模拟提供数据支撑,有利于城市水文及排水系统溢流的精细化管控。

       

      Abstract: Current urban drainage planning typically employs constant runoff coefficients to estimate urban runoff.However, under complex rainfall characteristics and diverse land cover types, the use of a single runoff coefficient is insufficient to meet the demands of increasingly refined management.Therefore, taking the complex urban area of Shanghai as the study subject, 11 land cover types were classified using high-resolution remote sensing imagery.Field dynamic runoff monitoring was conducted to analyze runoff characteristics across these land covers.Hydrological parameters were determined using the SWMM model to investigate the relationships between runoff, infiltration, and rainfall factors in the region.Results indicated: ① compared with impervious surfaces, permeable surfaces exhibited reduced initial runoff of 6.4~15.7 mm during short-duration, high-intensity frontal rainfall events.Under prolonged, multi-peak rainfall, runoff onset was delayed by 3.5~23.8 hours.Vegetation interception and soil infiltration effectively reduced initial runoff or delayed runoff onset and peak timing.② Among eight impervious surfaces, runoff coefficients ranked as follows: concrete roofs > motor vehicle roads > outdoor car parks > plaza pavements > institutional pavements > tiled roofs > residential area pavements > sidewalks.Manning′s coefficients ranged from 0.012 to 0.021, while depression storage capacities varied between 2.71 mm and 3.91 mm.③ The runoff coefficient of three permeable surface types followed the order: grassland > scrubland > woodland.Manning′s coefficients and depression storage capacities ranged from 0.27 to 0.41 mm and 4.16 to 5.32 mm, respectively.④ Regional runoff coefficients under 15 rainfall events ranged from 0.58 to 0.89, with coefficients under heavy, torrential, or extreme downpours ranging from 0.76 to 0.89.⑤ Regional runoff volume exhibited a positive linear relationship with rainfall (R2= 0.995), while infiltration volume demonstrated a strong logarithmic correlation with rainfall (R2= 0.955).These findings provide data support for runoff source control and drainage system overflow simulation, thereby contributing to more refined management of urban hydrology and drainage system overflows.

       

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