Urban Drainage System Performance Assessment Method And Application Under Low Impact Development

Frequent rainstorms and urban waterlogging pose a great threat to people's lives and property.In 2014,the Ministry of Housing and Construction issued the "Sponge City Construction Technical Guide-low impact Development Rain Water system Construction(trial)",which aims to improve the resilience of cities to natural disasters through low impact development measures combined with urban drainage system.In 2015,?Performance assessment and assessment method for the construction of sponge city? was promulgated.However,most of indicators are qualitative indicators,which are difficult to quantify and are the acceptance assessment after the completion of the project.There is an urgent need for a reasonable index system to evaluate the effect of the design scheme.In the context of climate change and sponge city construction,it is very important and urgent to design an elastic and sustainable urban drainage system.The research on the performance assessment method of urban drainage system under low impact development is the key,which has important theoretical significance and application prospects.This study firstly discusses the assessment index system,assessment method and assessment framework,and then carries out case application research on the proposed indicator system and assessment framework.In the research case,two drainage areas of Hefei and Huainan were selected respectively,according to the layout of different rain water pipe networks,low-impact development(LID)facilities are set up,various indexes are established,and MATLAB coupling SWMM software is used.The model simulation,scientific calculation and analysis are carried out,and the following results and main conclusions are obtained:(1)From the point of view of system elasticity and system sustainability,and multi-dimensional index integration,the performance assessment index system,assessment method and assessment framework of urban drainage system under low impact development are constructed.Considering not only the different threats such as system failure,but also the cost,maintenance and operation cost,environment and social effect of the system,the assessment is more comprehensive and concrete,and according to the social and environmental indexes,the measurable measurement factors are given.It ensures the maneuverability and objectivity of the assessment,and avoids the subjectivity of artificially setting the weight of the assessment index through the geometric average algorithm.(2)The calculation results of Hefei case are as follows: the sustainability index is 0.77;the resilience index is 0.527;and the comprehensive index is 0.6.The calculation results of Huainan case are as follows: the sustainability index is 0.69;the resilience index is 0.541;and the comprehensive index is 0.61.The calculation of the two plots shows that the economic indicators in the sustainable indicators are relatively low,indicating that we can further optimize the selection and layout of LID facilities in the planning and design stage to obtain the most economical design scheme.(3)Different rainwater pipe network layout methods lead to higher resilience index of rainwater pipe network in Huainan area than Hefei area.In the absence of LID facilities,there is only one drainage outlet when a certain land parcel is arranged in Hefei Binhu District,and the resilience index is 0.530;the dispersed drainage outlet is arranged when a certain plot of Huainan Panji District is arranged,and the resilience index is 0.589.It shows that the distributed drainage is more resilient and more advantageous than the centralized drainage.(4)The comprehensive performance index of both plots is greater than 0.6,indicating that the urban drainage system performance assessment method under low impact development is feasible and can be applied to different rainwater network layouts;and the design of the rainwater network and the layout of the LID are both meet the requirements,the entire system is resilient and sustainable.(5)The feasibility of this assessment method and assessment framework was verified by the application of two cases in Hefei Binhu District and Huainan Panji District.The urban drainage system assessment method and assessment framework proposed in this paper can provide flexibility and sustainability assessment for rainwater pipe network and LID facility solutions,and provide scientific basis and reference for design improvement.