Author(s): Amir Rezvani; Zahra Kalantari
Linked Author(s): Zahra Kalantari
Keywords: NbS wetland placement flood risk management GIS hydrological modeling urban resilience
Abstract: In response to the growing challenges of climate change, urbanization, and flood risks, the integration of Nature-Based Solutions (NbS), such as wetlands, has gained prominence in managing catchment-scale water and sediment dynamics. This study explores the strategic placement of wetlands as a multifunctional NbS for flood risk mitigation, water retention, and ecological restoration within two catchments in the Uppsala region, Sweden. The research combines advanced geospatial analysis, hydrological modeling, and participatory decision-making to optimize the locations of over 200 potential wetland sites. These sites were identified using a sediment connectivity model that integrates hydrological, geomorphological, and climatic datasets, enhancing the capacity to predict optimal wetland placement based on water and sediment flow dynamics. The study employs high-resolution data, including Digital Elevation Models (DEMs), land cover, soil type, soil moisture maps, and precipitation data, to perform a comprehensive analysis of connectivity across the catchments (Kalantari et al., 2017), guiding the identification of areas where wetlands can most effectively contribute to water management and flood mitigation. Wetlands, as essential elements of NbS, provide a range of ecosystem services, including nutrient retention, flood regulation, and habitat creation. However, the strategic placement of these wetlands is key to maximizing their effectiveness. This research integrates both structural and functional connectivity aspects, which are essential for understanding sediment and water movement across catchments. Structural connectivity refers to the physical pathways that water and sediment follow, while functional connectivity reflects the dynamic processes that govern these movements, especially under changing climatic and land use conditions (Cavalli et al., 2013; Heckmann et al., 2018). The study uses sediment connectivity indices (ICs), which quantify how well-connected different areas are within the landscape, to identify priority zones for wetland implementation. In addition to the connectivity model, a depression analysis was conducted to identify further potential wetland sites based on topographical and hydrological characteristics. This method targets natural depressions, which offer optimal storage capacity for floodwater, reducing the need for extensive excavation and supporting the principles of NbS. To ensure the feasibility of these wetland sites, the study employs a combination of decision-support tools, including the Analytic Hierarchy Process (AHP) (Saaty, 1987), Multi-Criteria Decision Analysis (MCDA) (Huang et al., 2011), and Multi-Objective Decision Analysis (MODA), to prioritize sites based on multiple objectives such as flood mitigation, water retention, and biodiversity enhancement. The AHP allows for the integration of stakeholder input, providing a transparent process for weighing the relative importance of different wetland functions. MCDA and MODA were used to rank potential sites across both ecological and socio-economic criteria, ensuring that selected locations align with both environmental goals and local community needs (Malczewski, 2006). The findings from this study underscore the importance of using digital tools and participatory frameworks in designing resilient urban landscapes. By mapping and analyzing hydrological and sediment connectivity, this research offers a comprehensive strategy for placing NbS within catchments to maximize their environmental and socio-economic benefits. The results also contribute to the growing body of knowledge on how wetlands and other NbS can be integrated into catchment-scale management plans, especially in urbanizing and flood-prone regions. This approach provides critical insights into how NbS can be deployed at a catchment scale to address flooding risks, improve water quality, and enhance biodiversity, offering scalable solutions for cities facing similar challenges. This research is part of a broader effort to apply digital twin technology in catchment management, integrating real-time data to update and optimize water management practices continuously (Kalantari et al., 2021). Through developing digital models and decision-support tools, this study demonstrates how advanced hydrological and environmental data can drive the successful implementation of NbS, aligning with integrated flood risk management (IFRM) strategies. It also highlights the need for close collaboration with stakeholders to ensure that these solutions meet both ecological and community needs, ensuring long-term sustainability in the face of climate change. References Cavalli, M., Trevisani, S., Comiti, F., & Marchi, L. (2013). Geomorphometric assessment of spatial sediment connectivity in small Alpine catchments. Geomorphology, 188,31-41. https: //doi. org/https: //doi. org/10.1016/j. geomorph. 2012.05.007 Heckmann, T., Cavalli, M., Cerdan, O., Foerster, S., Javaux, M., Lode, E., Smetanova, A., Vericat, D., & Brardinoni, F. (2018). Indices of sediment connectivity: opportunities, challenges and limitations. 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In Nature-Based Solutions for Flood Mitigation: Environmental and Socio-Economic Aspects (pp. 339-354). Springer. https: //doi. org/http: //dx. doi. org/10.1007/698_2021_771 Malczewski, J. (2006). GIS‐based multicriteria decision analysis: a survey of the literature. International journal of geographical information science, 20 (7), 703-726. https: //doi. org/https: //doi. org/10.1080/13658810600661508 Saaty, R. W. (1987). The analytic hierarchy process -- what it is and how it is used. Mathematical modelling, 9 (3-5), 161-176. https: //doi. org/https: //doi. org/10.1016/0270-0255 (87) 90473-8
Year: 2025