Assessing the long-term effectiveness and socioeconomic benefits associated with ecosystem-based disaster risk reduction measures aimed at mitigating the impact of sediment-related events in Nepal

The Ecosystem-based Disaster Risk Reduction (Eco-DRR) approach is widely used for slope stabilization and erosion control, yet its long-term effectiveness, structural integrity, and socioeconomic benefits remain insufficiently understood. This study qualitatively assesses countermeasures to geohazards that were implemented at three sites in Nepal as part of the Japan International Cooperation Agency's (JICA's) technical cooperation projects, using locally available materials (rock-filled wire gabions and vegetation). Photo-based comparisons revealed an increase in vegetation cover over 20 to 30 years in previously degraded areas. Gabion check dams stabilized gullies and trapped sediment, but experienced deterioration due to wire corrosion and breakage. A debris flow at Nallu Khola triggered by torrential rainfall on 26–28 September 2024 further exposed the vulnerability of these structures to extreme events, emphasizing the need for more resilient designs. Vegetation-based countermeasures provided livelihood benefits by supplying bamboo for fencing, livestock feed, and household materials. However, economic development has shifted residents toward market-based livelihoods, reducing their reliance on these resources. The sustained activities of the JICA-established user groups highlight the potential for long-term community engagement in land and forest management. While qualitative data offer initial insights, quantitative assessments are needed for precise and standardized evaluations of the countermeasures' effectiveness. • Eco-DRR countermeasures promoted vegetation recovery and reduced erosion. • Gabion check dams stabilized gullies but deteriorated due to wire corrosion. • Extreme events exposed structural vulnerabilities, requiring more resilient designs. • Vegetation-based measures could provide essential resources for local residents. • JICA user groups demonstrated lasting community engagement in land management.