Estimating landslides vulnerability in Rwanda using analytic hierarchy process and geographic information system.

Area of Science:

• Geosciences
• Environmental Science
• Risk Assessment

Background:

• Landslides pose significant social, economic, and environmental risks to communities.
• Vulnerability assessment is crucial for effective disaster preparedness, response, and mitigation.

Purpose of the Study:

• To estimate landslide vulnerability in the western province of Rwanda.
• To identify key factors contributing to landslide occurrence and severity.

Main Methods:

• A landslide inventory map was created from field surveys and secondary data (96 landslides).
• Ten conditioning factors (altitude, slope, NDVI, land use, distance to roads, soil texture, rainfall, lithology, population density, communication tools) were analyzed.
• The Analytical Hierarchy Process (AHP) and Weighted Linear Combination (WLC) within a Geographic Information System (GIS) were employed for spatial estimation.

Main Results:

• Altitude (19.7%), slope angles (16.1%), soil texture (14.3%), lithology (13.5%), and rainfall (12.2%) were identified as the most significant vulnerability factors.
• A landslide vulnerability map was generated, classified into five categories: very low, low, moderate, high, and very high.
• Validation using the relative landslides density index (R-index) confirmed the map's accuracy, with a significant percentage of past landslides falling into moderate to very high vulnerability zones.

Conclusions:

• The methodology effectively estimated landslide vulnerability and produced a reliable vulnerability map for the study area.
• The findings provide valuable data for policymakers to implement hazard mitigation strategies and inform future land-use planning.
• The study underscores the importance of integrating various geospatial data and analytical techniques for robust landslide risk assessment.