Green infrastructure design and evaluation model for resilient sponge city program transitional construction

Green Infrastructure (GI) has gained tremendous interests in the Sponge City Programs (SCP) after being identified as one of the key strategies for achieving sustainability and resilience. More recently, in the context of China's socially motivated transformation to ecological civilization, ensuring high-quality urbanization is oriented towards sustainable economic, environmental, and social development. Based on literature review, two research gaps were identified. Firstly, in terms of the macro-scale, there are limited studies on how to define and develop the multi-objective framework focused on resilient outcomes in SCP by integrating ecological and social resilience enhancements strategies. Secondly, in terms of the meso- and micro- scale research, there is a lack of comprehensive and quantitative evaluation system for the transitional development towards sustainability. This study aims at a GI planning and assessment model for SCP to achieve reinforced resilience and sustainable outcomes, especially for cities in Jiangnan water net area of china. Consequently, the novelty of this research is primarily reflected in its potential to reshape the sponge project through the development of a high-quality GI planning and assessment model. The developed model contains enhanced resilience and sustainable strategies, and implementable solutions with multi-dimensional and multi-spatial functionalities for satisfying the high-quality transitional trends and needs. The developed Basic Strategies and Pathways Framework (BSPF) laid emphasis on the impact analysis and evaluation within the whole GI planning process, by refining the impact evaluation process and integrating a more comprehensive key Performance Indicator Framework (KPIF). This KPIF incorporates a set of Key Performance Indicators (KPIs), which enabled the quantitative evaluation of the design alternatives, thus supporting robust decision making for the selecting the optimal solutions. Furthermore, the developed BSPF model and KPIF were applied to the Siming Lake watershed case study. A water resilience centered, multi-objective and more resilient GI network model was identified for the whole watershed. At the meso-scale, this study utilized Stormwater Management Model (SWMM) and the Analytic Hierarchy Process (AHP) system to compare the effectiveness of multiple design scenarios. These scenarios were designed with different combination of site scale Green Stormwater Management (GSI) facilities (denoted as SS1-SS10), a basic GI scenario that only recovers green landscape without GSI facilities (denoted as SS11) and the current status quo benchmark (donated as SS12). After the comprehensive evaluation, the results show that SS4 presented the best performance with maximum benefits. At the micro-scale, four scenarios with different combination of additional GSI facilities (denoted as ZS1-ZS4) were developed and scenario ZS3 was identified as having the best performance. Furthermore, based on the expert interviews and taking consideration of the GI planning and implementation barrier such as lack of funding and some inadequacies of the local social management system, targeting the meso-scale GI planning and management system is recommended as the key links of this model. For the multi-objective restoration of the key node of river Daxi estuary wetland site, the most important short-term construction measures of the plan includes the demolishing of buildings in areas with high flood risk and high ecological sensitivity and the functional renewal of some good quality buildings. On this basis, the coordination between various scales for the holistic management and implementation of supporting policy for SCPs GI Planning were discussed. In brief, the developed model incorporates GI planning strategies for enhanced urban resilience to mutually benefit nature and people. This exploration emphasizes that multifunctional GI system should not only focus on the sustainability of the ecological resilience, but also simultaneously improve the social resilience and ensure cost e fectiveness. The development of the BSPF model with KPIF, its application, evaluation, optimisation, and policy discussions collectively provide useful design and evaluation tools and valuable references for both designers and administrators who are undertaking similar planning projects.