北京典型汇水区域雨水径流温度特征及影响因素分析

Analysis of temperature characteristics and influencing factors of the stormwaterrunoff in typical catchment in Beijing

城市化发展导致不透水地表面积率大幅攀升,由此带来的一系列问题逐渐受到人们关注,夏季城市汇水区域地表产生高温径流后汇入下游受纳水体所造成的雨水径流热污染,对水生态、水环境造成不良影响的风险尤为突出。选取北京市典型汇水区域,对2021—2022年多场降雨径流出流温度进行监测与分析,并对气象因素、下垫面温度及管道内径流热量等数据进行同步采集,运用皮尔逊相关系数法分析其影响因素。结果表明:研究区域夏季降雨常出现雨水径流温度升高现象,降水量小于12.5mm、降雨历时短于250 min的降雨场次更易于升温,升温幅度最高可达4.1℃;径流温度升高往往出现在径流过程初期,温度达峰平均时间为38 min;径流是否升温与降雨强度峰值位置之间没有明显关系;气温、不透水地表初始时刻温度、降雨历时及降水量是雨水径流温度的极显著影响因素(P<0.01);降雨期间气温、降雨历时、不透水地表初始时刻温度和管道内壁温度4个指标,可以基本解释研究区域96.7%的径流温度输出情况。

With the development of urbanization,the rate of impervious surface area has increased greatly,and a series of problems have attracted more and more attention.The risk of adverse impacts on the water ecology and water environment has become more and more prominent in the summer when the surface of the urban catchment produces high temperature runoff and then sinks into the downstream receiving water bodies caused by the thermal pollution of stormwater runoff.A typical catchment in Beijing was selected to monitor and analyze the runoff temperature of several rainfall events from 2021 to 2022.The data of meteorological factors,underlying surface temperature and pipeline runoff heat were collected simultaneously,and the Pearson correlation coefficient method was applied to analyze the influencing factors.The results showed that the temperature of stormwater runoff often increased in summer rainfall in the study area,and rainfall events with precipitation less than 12.5 mm and durations shorter than 250 min were more prone to warming,with a maximum warming of 4.1℃.Runoff temperature increases tended to occur at the beginning of the runoff process,with an average time to peak of 38 min,and there was no obvious relationship between the temperature rise and the peak location of rainfall intensity.The highly significant(P<0.01)influencing factors of stormwater runoff temperature included air temperature,precipitation,rainfall duration,and the impervious surface temperature at the initial moment of rainfall.The four indicators of air temperature during rainfall,rainfall duration,impervious surface temperature,and pipe wall temperature at the initial moment could explain 96.7%of the runoff temperature output in the study area.