Manambolo river watershed study and diagnosis, Madagascar
Problems
The Manambolo watershed in western Madagascar is frequently threatened by multiple natural hazards, including floods, forest fires, erosion and landslides, and cyclones. The watershed is home to a large diversity in ecosystems and communities. To strengthen the local capacity to cope with these natural hazards, the French Red Cross (FRC), together with World Wide Fund for Nature (WWF), is planning a project to promote the resilience of communities and forests to climate-related hazards through an ecologically sensitive Disaster Risk Reduction (eco-DRR) strategy.
Solutions
To facilitate the eco-DRR project, Resilience, together with project partner HKV, conducted a multi-hazard assessment for the Manambolo watershed in Madagascar. An analysis was carried out of various hazards that are identified as being pertinent in these areas, including floods and forest fires, as well as other hazards that are posing a direct threat to the population and ecosystems. A landscape approach is adopted, considering the geology, the hydrology, land uses and population distribution of the area. The scope of the study was to undertake a diagnosis on multiple hazards as well as to deliver on key vulnerabilities and associated risk-reducing actions in the Manambolo river watershed. The considered hazards in the study are floods, bush fires, cyclones, and landslides/river erosion. In order to support the development of an eco-DRR action plan, the watershed was studied, adopting a multi-layer analysis including the interactions and interdependencies between ecosystems and human socioeconomic systems. For this purpose, the following elements were defined as objectives of the study:
• Identification of intervention zones based on risk profiling,
• Assessment of the current risk management systems,
• Recommendations regarding physical and non-physical interventions.
Impact
After mapping of the various risk, affected areas and damages were calculated per hazard type and scenario (i.e. different return periods of floods). Results indicated that in most communes, fires and floods were considerable risks. In a field campaign target areas were visited together with local stakeholders to get a better understanding of the situation on the ground, which was used to verify desk study and modelling results. This resulted in the finding that most fires were actually initiated on purpose for the clearing of agricultural lands, which was not seen as problematic by the communities. However, floods frequently made roads impassable, disrupting local transport, which as seen as a major issue. Additionally, these floods sometimes destroyed newly planted agricultural fields, resulting in loss of yield and potentially famine. Following the findings of the flood risk assessment, several recommendations for physical as well as non-physical measures were formulated, including an estimation of costs and impact of measures.
