| China’s rapid urbanization process has led to many problems: water pollution,the frequent occurrence of waterlogging disasters,and the destruction of aquatic ecosystems.In this context,the concept of "sponge city" was created."Sponge city" not only adapts to environmental changes but also responds to natural disasters.Construction "Sponge city" should coordinate the low impact development stormwater systems,urban stormwater conduit systems,and excessive stormwater runoff discharge systems.This paper takes the main area of Chongqing Yuelai New District.Usesd InfoWorks ICM to establish storm water model.One-dimensional pipe network model was used to assess the drainage capacity of rainwater drainage pipe,and improvement measures for stormwater pipe networks in mountainous cities were proposed;the intrinsic risk assessment was conducted through the two-dimensional flood submergence model to analyze the causes of waterlogging in mountainous cities;and LID assessments were made through LID facility hydrological modules.The main research contents and results are as follows:Summarized the status of foreign advanced urban stormwater management and the developing process of domestic “sponge city”.The hydrological model used in this paper includes the runoff yield model and the confluence model.The hydraulic model used in this paper includes one-dimensional hydrodynamic model and two-dimensional hydrodynamic model.Analysis of four types of rainstorm patterns calculation method.Based on the Chicago method to calculate the 180 minutes design rainstorm at Yubei,and the return period are 1,2,3,5,10,50 and 100 years.The storm water model of Yuelai Eco City was established in InfoWorks ICM,and the drainage capacity of rainwater drainage pipe was evaluated through a one-dimensional pipe network model.The main evaluation indicators are overflow nodes and overload conduits.The results show the necessity of assessing the drainage capacity of rainwater drainage pipe in the newly constructed rainwater drainage system.This paper put forward the optimization measures for storm sewer system in mountainous cities are to optimize the rainwater catchment and optimize the pipe diameter,and have been verified in the model.It provided optimization suggestions for the construction of rainwater pipe networks in the study area.The survey found 49 waterlogging points in the main urban area of Chongqing and was divided into four categories according to the locations.Ordinary roads,interchanges or ramps,riverside roads and communities.The causes of some typical waterlogging points were analyzed,and the corresponding reconstruction plans were proposed.According to the analysis,the causes of waterlogging in mountainous cities include: terrain height difference and low-lying,problems in urban drainage systems(drainage capacity of stormwater pipelines,insufficient capacity of rainwater pipe network systems,plugging of rainwater pipe network systems,rainwater confluence in some areas,and unreasonable rainwater drainage zones).There are few emission reduction measures in the early stage of rainwater and the informatization level of drainage facilities is low.Through the two-dimensional flood submergence model in InfoWorks ICM,the situation of water accumulation under the return period of 10 years,50 years and 100 years was simulated.It was found that the places where water logging occurred in the study area were scattered and were mostly located on the roads of local low-lying terrain.The indicators of risk assessment of waterlogging in mountainous cities are included: the degree of water accumulation and the target of impact.To make a risk assessment of the intrinsic risk of Yuelai New District in a design rainstorm in 50 years.The LID facility hydrology module in InfoWorks ICM was used to simulate the effects of bio-retention ponds and reservoirs in LID reconstruction of the Yuelai Guobo Area.The results show that the LID facility has a substantial effect on the reduction of runoff and is conducive to the use of rainwater resources. |
