Urban resilience assessment: A multicriteria approach for identifying urban flood-exposed risky districts using multiple-criteria decision-making tools (MCDM)

As cities are vulnerable to diverse climate threats, operationalizing cities efficiently by addressing flood risk becomes an irreversible step. So, our research developed a multicriteria paradigm for identifying where are flooding-exposed risky districts that should be prioritized for interven-tion? based on two powerful indicators: flood vulnerability and flood exposure. Our method-ology was tested in Alexandria, Egypt, which experiences the harshest rainfall annually and variations in socioeconomic and urban patterns like most global cities. One hundred thirteen climate-related Egyptian experts evaluated 44 flood risk-related indicators; the indicators were ranked using fuzzy AHP, followed by the differentiation of regions using TOPSIS, VIKOR, and WSM methods. Finally, map risky districts using interrelated horizontal layers of indicators. Our findings indicate that the spatial distribution of flood-prone districts increased in proximity to the traditional patterns of the city center and decreased when moving towards the dispersed patterns of the city's outskirts, indicating that urban form is a more effective indicator and has dual aspect effects (increase and decrease) in flood reduction when combined with other non-spatial in-dicators. Finally, a validation study was conducted to define the spatial congruency or mismatch between the simulated and realistic conditions. So, based on runoff data from 2015 to 2021, a deterministic coefficient (RC) and Nash-Sutcliffe efficiency (NSE) index were calculated with values of 0.89 and 0.93, respectively, indicating our analysis performed well. Our approach may assist policymakers in overcoming the shortage of data for contingency planning, especially in developing countries.

Automated summary

Given the vulnerability of cities to various climate threats, it is essential to address flood risk and operationalize cities efficiently. Our research developed a multicriteria paradigm using flood vulnerability and flood exposure indicators to identify flooding-exposed risky districts that should be prioritized for intervention. The methodology was tested in Alexandria, Egypt, and demonstrated the effectiveness of considering urban form as an indicator in flood reduction. The findings highlight the applicability of our approach for contingency planning and addressing data shortages in developing countries.