Comprehensive Assessment Of Resilience Of Sustainable Urban Drainage System

Building a resilient city is one of the development goals of the United Nations human settlements.In recent years,low-impact development(sponge city)measures have been increasingly valued globally and are increasingly being applied to the design and management of urban drainage systems to enhance the flexibility of urban stormwater systems.However,on the one hand,evaluation and quantification of resilience There are certain difficulties.The definitions of resilience are different in different fields,which leads to different evaluation models.On the other hand,the resilience assessment of sustainable urban drainage systems often focuses on flood prevention and other aspects.Sponge City technical measures and urban rainwater systems(named as “sustainable urban drainage systems”)are often given multiple objectives,and existing research has major limitations.This study aims to establish a multi-objective sustainable rainwater system resilience assessment system,study the impact of different LID configuration schemes on system resilience,and its mitigation effects on climate change,urban development and other pressures,and provide program selection reference for urban drainage system planning designers.This study develops a more comprehensive resilience evaluation system by combing the concept of resilience and combining the multifunction of sustainable urban drainage system,and proposes an optimization method for the decision-making of sustainable urban drainage system solution based on resilience evaluation.The resilience's quantification and evaluation as well as its case study are the focus of this study.Through the analysis of the concept of system resilience,three aspects of resilience content are proposed,including the resilience of urban flooding,the resilience of river water pollution and the resilience of alternative water supply.Through the analysis of the response process of the system in terms of these 3 aspects,the process of resilience change is clarified,and the specific quantitative formulas of the three resilience indicators are proposed.The weights determined by the analytic hierarchy process are combined to form the total resilience of the system.The quantification of resilience index is based on the hydrological model Infoworks ICM and water balance calculation model using Excel VBA.The basic data such as local rainfall intensity,topography and land use planning are collected and simulated.The design of sustainable urban drainage system is based on LID and local planning requirements.Five options were set up represent traditional solution(BASE),bioretention solution(BR),permeable paving solution(PP),rainwater harvesting solution(RWH)and hybrid solutions respectively.By predicting climate change and urban development trends,we will set uncertain disturbance scenarios by proportionally changing the rainfall intensity and impervious area ratio.Through the application of the newly established resilience assessment system,the total resilience and 3 sub-resilience performance of 5 solutions under the baseline scenario and uncertain disturbances scenarios such as climate change and urban development are evaluated.This paper takes the Y District of Chongqing as an example and uses the abovementioned resilience assessment method to apply its sustainable rainwater system.The evaluation results show that combined with the three sub-resilience such as urban flooding,water pollution and alternative water supply,the highest total resilience is the reservoir and mixing scheme,followed by the permeable paving and bioretention scheme;the mixing scheme is in the three sub-resilience indicators.It has a good performance,so it is recommended as the optimal solution.It also proves that the evaluation of system resilience is more reasonable when considering more extensive standards.The overall resilience of the five programs is declining considering the future uncertain scenarios of climate change and urban development.Trends,hybrid schemes appear as optimal schemes in uncertain scenarios,indicating that the scheme of selecting multiple LID measures to decentralize combinations has better performance and higher system flexibility than LID measures alone.The case study results show that the proposed sustainable urban drainage system resilience assessment system has a more comprehensive performance and can be used for sustainable rainwater system scheme selection and multi-objective optimization decision-making.