Implementation of nature-based solutions for flood & drought risks reduction using Numerical Modelling

Nature-based solutions (NBS) for climate change adaptation and natural hazard management are receiving much attention in Europe and across the world. It is now seen broadly as a valid measure to manage flood risk sustainably whilst providing significant multiple benefits. However, there is little information regarding its implementation and cost-effectiveness in reducing flood hazard at the watershed scale. This work focuses on NBS for flood risk management along with its challenges, opportunities and advancement. A comprehensive list of NBS used against flood risks was reviewed and the four best NBS – which are effective and economical under current and future climate change scenarios were selected based on multi-criteria decision-making process, and their suitability were tested through physical modelling. The design, optimal allocation and implementation procedures as well as the cost-benefit analyses were presented for the individual NBS. Probability distribution function (GEV model) was used to perform cost-benefit analysis (total expected cost including damage and construction) and flood estimation with and without NBS in place. The analyses showed that the performance and cost-effectiveness of NBS was lesser for short duration while the net benefits increased with time and became higher for the long duration. We formulated a recommended protocol based on the identified challenges, gaps and success for designing robust and effective NBS, its implementation, monitoring, evaluation, uptake and replication which could inform engineers, landscape architects, city planners, policy/decision-makers. This study builds up solid evidence base showcasing the benefits of flood NBS ensuring long-term sustainability and supply of ecosystem-services