EVALUATE NATURE-BASED SOLUTIONS FOR FLOOD MANAGEMENT IN CHINESE CITIES: A CASE STUDY OF NINGBO, ZHEJIANG

This Master's Project delves into the pressing issue of flood management strategies in Ningbo, China, a region vulnerable to riverine flooding. As China experiences an unprecedented surge in urbanization, propelled by rapid industrialization and economic growth, cities face a plethora of challenges, including strained infrastructure, environmental degradation, and increased vulnerability to climate change impacts. The study aims to evaluate the effectiveness of NbS in enhancing urban resilience against flood risks, addressing the intricate interplay between urbanization and environmental degradation.

The research employs a mixed-methods approach, combining quantitative spatial analyses with qualitative literature reviews and document analyses. A systematic review of policies related to NbS in China reveals that while the country lacks a comprehensive policy system dedicated to NbS, relevant policy contents are scattered across various ministries, each using context-specific terminology. The study identifies flood management as the most pressing challenge faced by Chinese coastal cities, particularly in the Yangtze River Delta, where millions of people are already exposed to the serious risks of severe floods and storms, a phenomenon expected to intensify due to climate change.

Through GIS-based Analytical Hierarchy Process and Multi-Criteria Decision Analysis, a flood susceptibility map is generated to identify high-risk areas along Ningbo's riverbanks. The analysis integrates diverse criteria, such as elevation, slope, rainfall, and land use land cover, into a unified decision-making process. Considering complex socio-economic factors, Fenghua River in Guangdu Village, Fenghua District, is selected as the research site for examining the implementation of Setback Levees as the preferred NbS.

A Cost-Benefit Analysis is conducted to assess the economic viability of implementing Setback Levees in the selected area over a 10-year period. The analysis covers initial and ongoing expenses, reduction in flood-related damages, opportunity costs, transaction costs, and potential ecological or social externalities. The results demonstrate a favorable Benefit-Cost Ratio of approximately 11.95, indicating that the potential benefits significantly outweigh the costs. Sensitivity analysis further confirms the robustness of the project's economic feasibility under various scenarios.

The findings contribute to the strategic planning and implementation of flood control measures that are adaptive to climate change, sustainable, and aligned with ecosystem-based management principles. The study highlights the potential of NbS as a cost-effective and environmentally sustainable alternative to traditional flood control measures, offering valuable insights for urban flood management in Ningbo and other delta cities across China facing similar challenges of urbanization and climate change. By integrating NbS into urban planning and policy frameworks, cities can build resilience to climate change while simultaneously promoting ecological sustainability and socio-economic development.