Reshaping Rwanda’s Landscape: How Nature-Based Interventions Tackle Landslides

Researchers in Rwanda found that Ecosystem-based Adaptation (EbA) interventions, including forest restoration and terracing, significantly reduced soil erosion and landslides by 62.6% in the hilly Rubyiro sub-catchment. These nature-based solutions improved land sustainability and safeguarded local livelihoods.

A study conducted by researchers from the University of Rwanda's College of Agriculture Science and Veterinary Medicine, and Rwanda Polytechnic’s Department of Agricultural Engineering, focused on controlling soil erosion and landslides through Ecosystem-based Adaptation (EbA) interventions in the hilly landscape of the Rubyiro sub-catchment in the Rusizi District, Western Rwanda. The region is known for its vulnerability to natural disasters, particularly soil erosion and landslides, which have been exacerbated by deforestation, unsustainable agricultural practices, and climate change. The study aimed to assess the effectiveness of EbA interventions, such as forest restoration and the creation of terraces, in reducing these hazards and improving land sustainability in one of the most affected regions of the country.

The study area is characterized by steep slopes, high rainfall, and intensive agricultural activity, which makes it prone to soil erosion and landslides. The researchers employed a mix of data collection methods, including remote sensing techniques, Geographic Information System (GIS) tools, and the Revised Universal Soil Loss Equation (RUSLE) model, to estimate soil loss before and after the implementation of the EbA interventions. Additionally, a survey was conducted among local farmers and officials to gather their perceptions on the effectiveness of these measures. A total of 354 respondents participated in the survey, which included both farmers and sector officers responsible for agriculture and natural resources management.

Reforestation and Terracing: Nature’s Defense Against Erosion

The EbA interventions, introduced between 2018 and 2019 by the local government, primarily focused on reforestation efforts and the establishment of progressive and bench terraces in the region. These interventions aimed to protect the soil by reducing surface runoff and enhancing vegetation cover, which can stabilize the soil and prevent landslides. Prior to the introduction of these measures, the region experienced frequent landslides and significant soil erosion, which had severe socio-economic impacts, including loss of fertile agricultural land, damage to infrastructure, and disruption of local livelihoods.

Soil Erosion Rates Plummet as EbA Interventions Take Root

The findings from the study demonstrated a significant reduction in both soil erosion and landslide occurrences following the implementation of the EbA interventions. Landslide events decreased by 62.6%, with forest restoration being recognized as the most effective measure. Approximately 72.4% of the respondents favored forest restoration as a key intervention in reducing the risk of landslides, while 26.1% and 1.5% preferred progressive terraces and bench terraces, respectively. The success of forest restoration in this context can be attributed to the role of trees and other vegetation in stabilizing the soil and absorbing excess rainfall, which reduces the likelihood of landslides in steep areas.

The RUSLE model, used to estimate soil loss, revealed a marked improvement in the region’s soil erosion rates after the EbA interventions were implemented. In 2017, before the measures were put in place, the estimated average annual soil loss was 11.9 tons per hectare. By 2018, this figure had risen to 17.6 tons per hectare due to increasing anthropogenic pressure and lack of soil management strategies. However, by 2021 and 2022, the annual soil loss had dropped to 10.1 and 9.3 tons per hectare, respectively. This reduction of 8.3 tons per hectare over four years highlights the positive impact of EbA measures in mitigating soil erosion in the Rubyiro sub-catchment.

Forest Restoration: The Pillar of Landslide Prevention

The study also found that soil erosion was particularly severe in areas where land cover had been significantly altered by human activity, such as deforestation and intensive farming. The restoration of forested areas through tree planting and re-vegetation efforts played a crucial role in reversing this trend by improving the region's soil structure and water retention capacity. The implementation of terraces further contributed to reducing soil erosion by slowing down the flow of water on steep slopes, allowing more time for the water to infiltrate into the ground and reducing surface runoff. While forest restoration proved to be the most effective intervention, the combination of different measures was necessary to achieve optimal results.

Economic Benefits: Preserving Livelihoods and Infrastructure

In addition to the environmental benefits, the study highlighted the socio-economic advantages of EbA interventions. Reduced soil erosion and landslide occurrences not only protect agricultural productivity but also help to safeguard local infrastructure, such as roads and bridges, which are often damaged by landslides. By reducing the frequency of these natural disasters, the EbA interventions also contribute to improved food security and economic stability for the local population, many of whom rely on agriculture for their livelihoods.

Future Focus: Scaling Up Nature-Based Solutions

The researchers concluded that EbA interventions have a critical role to play in managing soil erosion and landslides in Rwanda’s hilly regions, particularly in areas with similar topographical and climatic conditions as the Rubyiro sub-catchment. They recommend that local authorities continue to invest in these nature-based solutions and raise awareness among the community about the importance of maintaining and expanding these interventions. The study also suggests that future efforts should focus on incorporating rainwater harvesting techniques and restoring degraded landscapes to further enhance the resilience of the region's ecosystems.