城市雨洪模拟与年径流总量控制目标评估——以北京市未来科技城为例

Urban stormwater simulation and assessment of the control rate of total annual runoff:A case of the Future Science and Technology Park in Beijing

伴随城市化进程加快,硬化地表面积的增加,城市降雨径流过程已发生明显变化,导致洪涝问题突出。城市雨洪模拟是当前城市水文学研究热点和难点之一,也是城市洪涝防治、海绵城市建设评估的关键技术手段。本文选取北京市未来科技城为研究区,利用SWMM模型构建城市雨洪模型,模拟不同降雨条件下地表和管网径流过程;依据不同场次雨型设计年径流总量控制目标对应的降雨过程,并驱动已构建的雨洪模型,评估现状地块下年径流总量控制目标实现情况;据此,提出不同海绵措施的空间布局以实现年径流总量控制目标。结果表明:城市雨洪模型模拟精度较高,洪峰流量误差在8～26%之间,而峰现时间误差为-8%,-1%和0。现状地块条件未达到北京市年径流总量控制目标(80%);采用在道路、建筑和绿地分别增设透水铺装、绿色屋顶和下沉式绿地,并分别按20%,40%和40%的方案比例分配时研究区90%的地块均可达到年径流总量控制目标,还增加1.79万m^3可利用水量。本文既可为海绵城市年径流总量控制目标的评估提供参考借鉴,也可为城市海绵措施布局优化等提供决策依据。

Along with the acceleration of urbanization process,urban impervious surfaces have increased,and the urban rainfall and runoff processes have undergone significant changes,resulting in outstanding flooding problems.Urban stormwater simulation is one of the hotspots and challenges in current urban hydrology research.It is also a key technical means for urban flood control and total annual runoff control rate evaluation of'sponge cities.'In this study,the Future Science and Technology Park in Beijing was selected as the research area.We constructed an urban stormwater model using the stormwater management model(SWMM)to simulate surface and pipe network runoff processes under different rainfall conditions.We designed the precipitation processes corresponding to the control rate of total annual runoff according to the characteristics of different field rainfalls.Moreover,we drove the constructed urban stormwater model to assess the achievement of current land blocks with regard to the control rate of total annual runoff.On this basis,the spatial layout of different'sponge city'measures was proposed to achieve the control rate of total annual runoff.The results demonstrate that the model simulation accuracy was high.The peak errors of the three rainfall and runoff processes were between 8%~26%,and the peak time errors were-8%,-1%,and 0,respectively.Under the current land use conditions,the control rate of total annual runoff of the city of Beijing(80%)has not been reached.With the addition of permeable pavements,green roofs,and sunken green spaces of 20%,40%,and 40%,respectively on roads,buildings,and green spaces,90%of the land blocks would reach the control rate of total annual runoff,and the maximum amount of available water would reach 17870 m^3.This study can provide a reference for the assessment of the control rate of total annual runoff and specific decision-making basis for the optimization of the spatial layout of urban'sponge city'measures.