Assessment of combining large-scale and small-scale nature-based solutions to enhance urban drainage performance [MSc research thesis]

The uncertainty of climate change and urbanization has resulted in prominent flood problems in urban areas. Increasing research evidence suggests that the traditional grey infrastructures no longer provide the desired results and it has driven stakeholders to realize sustainable solutions. Nature-Based Solution NBS is a more ecosystem friendly approach and enhances the natural storage capacity of water by promoting urban hydrological cycle processes. NBS is a relatively new response to flood risks and has the potential for a more sustainable approach than traditional measures. However, grey infrastructures are widely adopted by the policymakers and stakeholders as the main response to flood management, therefore, NBS are applied at a slow rate. This is associated with a lack of sufficient knowledge of NBS to mainstream its wider uptake in practice. This research contributes to this direction and assesses the impact of combined large and small-scale nature-based solutions. The research has proposed a procedure to guide stakeholders on combining large and small-scale NBS. The procedure is then applied to a case study in Cali Colombia, and hydrodynamic models of a drainage network are used to assess the impact of the combinations on enhancing urban drainage performance. The results suggest that combining large and small-scale NBS are a potentially more effective and sustainable response to floods and this study recommend its wider uptake in urban planning. However, further research is expected to upscale nature-based solutions