Impact Of Urbanization Process On Drainage System And Modification Measures Analysis

In recent years, with the speeding up of urbanization and extreme weather occurs frequently, urban waterlogging phenomenon becoming serious increasingly. From the perspective of the urban drainage pipe network reasons, there are mainly two aspects:one is the increasing of urban impervious paving surface, leading to the increasing of production of runoff flow; Second is that the expanding in cities bring the discharge pressure of the downstream old drainage pipe network, and the common engineering measures used of the transformation costs lost. It is meaningful work that how to prevents waterlogging on the basis of controlling the cost.Currently, the common used engineering pipeline renovation measures including reservoirs, pump stations, permeable pavement and green infrastructure, etc. Reservoir is suitable for low-lying areas where is hard to drainage water, pump station is suitable for waterlogged areas where is next to receiving waters (rivers, lakes, etc.), while the permeable pavement and green infrastructure is suitable for urban areas where there are many impermeable area that can be easily reformed. And the above several measures, cost much and covers large area.In recent years, Hydro-Braker Optimum got many applications abroad. The facility is mainly by controlling the upstream water flow in the pipe network, bring the peak load shifting with the downstream peak flow in pipe network, so as to achieve the purpose of the slow downstream flooding pressure.In this paper, mainly study three aspects work applying SWMM model, combining ArcGIS, including the effect of the urbanization process on the drainage system, the analysis of Hydro-Braker Optimum and Scheme Optimization based on fuzzy decision theory(1) To study the effect of urbanization on the drainage system. Choose a certain area in Dalian as the research area, because of the urbanization process, on the one hand, the ground water permeability becomes weaker in the study area, on the one hand, the expansion on the basis of the original urban area, forming a new drainage pipe network system. SWMM model is applied in this article, on the condition of 3 years,5 years and 10 years return period of rainfall, the drainage pipe network system of urbanization is simulated. From three aspects analyze the influence of the process of urbanization to the drainage system, outlet condition、surface runoff and pipe line load condition. Concluded that, after the urbanization, surface runoff increase, on the condition that the original network has no corresponding modification to adapt to the new network, urbanization process increases the pressure of old drainage network, and node flooding appears.(2) Modification measures analysis based on Hydro-Braker. Apply Hydro-Braker to the new pipe network after urbanization. Under the condition of different return period rainfall, apply SWMM model to simulate and calculate the new pipe network before and after the addition of Hydro-Braker. From four aspects to analysis the effects of Hydro-Braker, i.e., the control effect on flow rate and flow velocity, the effect on node depth, the effect on node flooding and the effect on pipeline load. Results indicate that Hydro-Braker, can slow downstream flood, but in turn increased the upstream flow capacity, based on this kind of situation, in this paper the measure of Hydro-Braker, combined with reservoir was analyzed.(3) Scheme Optimization based on fuzzy decision theory. In this paper, four solutions about Hydro-Braker were designed by changing the location and number, using the theory of fuzzy decision method, choose the optimal solution, namely under the condition of minimum cost, in a reasonable position to achieve the optimal control effect. Choose flow capacity, the number of the nodes in the overflow, cost, etc.as evaluation Indexes, in 10 years return period rainfall condition, SWMM model was applied in the simulation and calculation of drainage system, to get the eigenvalue matrix. Apply binary vector method to get the weight of each scheme, finally calculated the superiority of various schemes sorting, it is concluded that the optimal solution.