Assessment of the Effectiveness of Ecosystem-based Adaptation (EbA) Interventions on Flood Risk Reduction in Karago Lake Watershed, Rwanda

Climate change has increased the frequency and severity of floods worldwide, particularly in vulnerable mountainous watersheds affected by land degradation and unsustainable land use practices. Ecosystem-Based Adaptation (EbA) has emerged as an important strategy for improving environmental resilience and reducing climate-related disaster risks. This study was conducted in the Karago watershed, Nyabihu District, Rwanda, to evaluate the effectiveness of Ecosystem-Based Adaptation (EbA) interventions. Researchers used community surveys and laboratory analyses of soil and water samples. Soil samples were taken from areas with and without EbA interventions and analyzed for physical properties at “Institut d'Enseignement Supérieur de Ruhengeri”. Water samples from Nyamukongoro river under EbA area and Busoro river under non-EbA area were tested at Rwanda “Institute for Conservation Agriculture” for quality parameters during both dry and wet seasons. To capture localized land use effects, three sub-samples were collected from each river at 300-meter intervals from their outlets to Karago Lake. To analyze the soil and water data we used the paired t-test. To assess perception on flood trends and flood levels, a structured questionnaire was administered to 187 respondents from surrounding communities within Karago lake watershed to gather local knowledge and experiences. To do so, the historical information on flood events, flood damage and the interventions, for 20 years (from 2005 to 2025) has been captured and Ms Excel was for the analysis. The results demonstrated that EbA section is moister (29.98%) with high silt (7.73%) as sign of healthier soils with more porous structure. The water quality indicators showed significant decreases in the turbidity (1153 mg/L to 899 mg/L) and the suspended load (from 961 mg/L to 683 mg/L) in the Nyamukongoro river passing under EbA part. The survey conducted indicated that the severity of the floods had reduced since 2015 because of EbA interventions carried out through reforestation, grassing and terracing. This was confirmed by 80% of respondents. The research helped to prove the proposition that EbA interventions are not an abstract solution but a viable and evidence-based alternative to reduce disaster risk, improve eco-performance and empower the most disaster-prone people. The study recommends Ministry of Environment, Rwanda Environmental management agency and stakeholders to scale up EbA interventions in other vulnerable watersheds in Rwanda. Key words: EbA, Climate change, climate resilience, flood risk, EbA interventions