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基于Win-TR55的小区域低影响开发水文效应评估

Assessing the Hydrological Effects of the Low Impact Development for the Small Catchment Scale Based on Win-TR55

  • 摘要: 随着社会经济的发展,城市化水平不断提高,改变了原始的下垫面条件,严重影响了水循环机制,由此引发一系列城市内涝、水环境污染等城市水问题。低影响开发(LID)能缓解城市化所引起的雨洪放大效应,而LID措施设计的一个关键性问题就是探究下垫面变化对洪水过程的影响。通过对比城市雨洪模型,选取Win-TR55模型,其为小流域设计洪水模型,该模型的产流核心为SCS-CN径流曲线模型,其突出的特点是计算过程简单、所需要的参数较少,并综合考虑了流域降水、下垫面类型等因素变化与径流之间的关系。基于上述模型分析了武汉市九龙生态公园的下垫面在现状、传统开发以及低影响开发条件下,模拟了不同重现期下的设计洪水过程,根据洪量、洪峰以及淹没范围的变化评估了低影响开发的水文效应。结果表明:(1)在3种开发模式下,传统开发下的CN值最大,低影响开发条件下的CN值最小;表明在低影响开发模式下,改变了下垫面类型,增加了调蓄容积,相应的CN值减小,产流量也减小。(2)在低影响开发条件下,一年一遇、五年一遇、十年一遇以及五十年一遇的洪量的削减率可达到:96.74%、81.58%、73.46%、61.13%,对于洪峰的削减率可达到:94.14%、70.63%、60.64%、45.42%。(3)设计淹没范围的削减率可达到:74.35%、63.60%、51.14%、6.83%;从模拟的结果可以看出,随着雨强增加,低影响开发的雨洪控制效果逐渐变弱。研究成果可为区域LID设施的设计提供水文依据。

     

    Abstract: With the development of society and economy, urbanization level continues to increase, which has changed the characteristics of the underlying surface. The water cycle has been seriously affected, leading to a series of urban water problems such as waterlogging and water environment pollution. Low Impact Development(LID) can alleviate the amplification effect of rainfall and flood caused by urbanization, and a key issue in the design of LID measures is to explore the impact of underlying surface changes on flood processes. This paper compares urban rainwater flood models and selects the Win-TR55 model, which is a small watershed design flood model. The core of this model is the SCS-CN runoff curve model, which is characterized by simple calculation process, less required parameters, and comprehensive consideration of the relationship between changes in basin precipitation, underlying surface type, and runoff. Based on the above model, the underlying surface of the Jiulong Ecological Park in Wuhan is analyzed under current, traditional, and low impact development conditions. The design flood process is simulated under different return periods, and the hydrological effects of low impact development are evaluated based on changes in the flood volume, peak, and inundation range. The results show that(1) under the three development modes, the CN value is the highest under traditional development and the CN value is the lowest under low impact development conditions. This indicates that in the low impact development mode, the type of underlying surface has been changed, the storage capacity has been increased, and the corresponding CN value has decreased, resulting in a decrease in flow rate.(2) Under the low impact development conditions, the reduction rates of flood volume for once every year, once every five years, once every ten years, and once every fifty years can reach 96.74%, 81.58%, 73.46%, and 61.13%, and the reduction rates for flood peaks can reach 94.14%, 70.63%, 60.64%, and 45.42%.(3) The reduction rates for the design inundation range can reach 74.35%, 63.60%, 51.14%, and 6.83%. From the simulation results, it can be seen that as the rainfall intensity increases, the flood control effect of low impact development gradually weakens. The study also found that as the rainfall intensity increases, the control effect of low impact development on rainwater and flood gradually weakens. The research findings can provide a hydrological basis for the design of regional LID facilities.

     

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