Application Of Drainage System Model And LID On Sponge City

The irregular of global climate lead to frequent storms, serious waterlogging and water pollution occur when cities in our country encounter heavy storms, they can cause losses to citizens’ lives and properties and destroy city daily order. Subject reasons of damages above are low construction standard for urban drainage system and large-scale missing of urban drainage system’s basic data, so drainage system in most cities of our country are severely damaged and hard to maintain. So far researchers around the world have developed various drainage system model with the big improvement of drainage system informatization, lots of countries accept the idea of LID and develop all kinds of technical measures. In this paper research of urban drainage system planning technology was carried out based on LID and pipeline network model, it provided a new solution for frequent urban waterlogging disaster.Perfect and accurate drainage system model was established through collecting basic data, importing model information, revising model elements, setting rainfall scenario and adjusting model parameters. The revising of model elements adopted site survey and cross-section method which could match elements’ physical attributes with actual situation. The adjusting of model parameters employed manual mode according to the comparison of measured results and simulated data to control the accuracy above 90%. In the setting of rainfall scenario, curve of single periodic rainstorm formula was transformed to Chicago rain type curve while the rain peak coefficient was set as 0.2. After detailed analysis of running status under 11 rainstorm recurrence periods, it came that severe overflow, large area of waterlogging and road block occurred in drainage system under high recurrence period. Based on the analysis above, the functions of various LID facilities and applicability of underlying surface were analyzed. Then 4 alternative LID facility construction schemes suitable for underlying surface were carried out to promote the storm resistivity of drainage system in study area. At last, the effectiveness analysis of 4 alternative LID facility construction schemes were performed using AHP, their effectiveness on runoff control and economy were compared synthetically. Through the effectiveness analysis above, the optimal construction scheme which could promote the running status of drainage system during storm efficiently and save construct cost was determined. Under the return period of 100 a, the optimal construction scheme’s reduction rate of total runoff volume was 40% while the decrease rate of overflow node, overflow duration and road blocking duration were above 70%.