Abstract
River systems worldwide are under significant anthropogenic pressures and climate-related challenges, leading to ecosystem degradation and increased flood risk. This chapter demonstrates how Nature Based Solutions (NbS) can contribute to river restoration while reducing flood risk, supporting wider sustainable goals. To this end, this chapter evaluates the effectiveness of NbS interventions in river restoration and flood risk management in the Kitwe City, Zambia. The methodology involves using a hydraulic model to simulate river flow under different NbS scenarios (retention ponds and woodland reforestation), and to compare the simulated flood depth and flow velocity in pre- and post-intervention conditions. The findings indicate that the presence of NbS significantly reduces flood risks, with retention ponds and woodlands leading to flood depth reductions ranging from 0.09 m to 0.18 m and 0.06 m to 0.11 m, respectively. Regarding flow velocities, retention ponds reduced them by an average of 0.11m/s, and woodlands, by 0.07 m/s. These results indicate that both NbS types reduce flood depth and velocity, with ponds being slightly more effective than woodland in the particular setting of the Kitwe District. The findings suggest that integrating NbS into river restoration can mitigate flood risks, improve ecosystem resilience, and contribute to long-term sustainability. These results inform risk management policies and emphasise the need for interdisciplinary collaboration to upscale NbS for maximum ecological and societal benefits.