Nature-based solutions for water management: insights to assess the contribution to urban resilience

Assessing the Nature-Based Solutions (NBS) contribution to urban resilience, along with developing tools capable of demonstrating their long-term value, comprises a most needed step forward. Nevertheless, the NBS contribution to urban resilience has been yet slightly explored. Given the urban resilience complexity and multiple NBS capabilities, specific needs for a robust assessment should be investigated. This paper identifies the requirements for a comprehensive assessment of the NBS contribution to urban resilience and analyses the main assessment frameworks focused on resilience and NBS for urban drainage. First, the evolution of the resilience concept and relevant resilience assessment frameworks (RAF) are presented. Secondly, NBS challenges to enhance resilience and NBS assessment proposals are analysed. Thirdly, the attributes for assessing urban resilience and aspects to assess the NBS contribution are analysed. To conclude, a critical analysis of the assessment approaches is presented. Important challenges across the RAF have been identified, especially regarding their feasibility of application. Based on the performed analysis, most RAFs are not feasible for city benchmarking and assessing the resilience evolution over time, neither for assessing comprehensively the NBS contribution. Regarding specifically the NBS assessment proposals, just one focused on urban resilience was developed to date, which allows evaluating their contribution over time, between cities, or between different NBS.