Evaluation And Analysis Of Urban Small Watershed Comprehensive Rainwater System Based On Drainage Model

Along with the rapid urbanization and the frequency of extreme heavy rainin China, the pressure of urban rainwater system is increasing. The developed countries have formed a new urban stormwater management concept based on Low Impact Development in the process of urban Development. In recent years, low impact development has developed quickly and been rapidly growing popularity in the city construction of China and the government also is giving great support. Nowadays, most developed countries have set up many perfect drainage mathematics models and evaluated the effect of LID facilities with the models.The drainage mathematics models also have been used to design and manage storm drainage systems in We should combine the research of finding weakness of the urban rainwater pipe network system with evaluating the effect of LID measures in regional development projects by using mathematics models, instead of being separate. Based on mastering the acceptable capacity of the urban municipal pipe network accurately, the paper is aimed at analyzing the storm drainage systems concluding LID facilities using in new or reconstructed projects and exploring a method of evaluating that whether the storm of new or reconstructed projects is discharged into the municipal pipe network or not before improving the return period of urban municipal pipe network.The storm drainage system mathematical model of the region in the south of Fengtai of Beijing was established with Info Works Integrated Catchment Management and verified by making use of historical rainfall data and the area and depth of emitting water supplied by the department in charge of operation and maintenance of municipal pipe network. At first, the current municipal drainage pipe network of the region in the south of Fengtai of Beijing was simulated and analysed. Then the effect that the stormwater in the building project discharged into municipal pipe network and the effect of control and utilization of rain was researched when the ability of external municipal pipe network is enough and not enough.The main results of the study are as follows:(1)the weakness of municipal drainage pipe network can be found by using the drainage model and improving the return period of the weak pipes from 1-2years to 3-5years is very difficult to realize.(2) the implementation situation of the planning of regional rainfall drainage must be surveyed. The data should be from the same year when evaluating the effect that the stromwater in the building project discharged into municipal pipe network. The conditions that municipal drainage pipes was built after the construction project was built and the downstream pipes were repaired after the upstream pipes were repaired should be noticed.(3) the effect of rainfall peak load shifting and decresing and storage of the stormwater by taking various measures to control and utilize the rain is better than taking a measure. The aim of low impact development can be achieved by permeating and be stored and stagnated of stormwater when the ability of municipal drainage pipes is not enough.Drainage model technology can provide a reference for the upgrade and modification of existing urban rainwater system and the evaluation of stormwater drainage systems in new or reconstructed regions. It will be another hotspot about urban drainage model technology.