Mapping landslide risk and vulnerability at district level in La Paz, Bolivia. Case study: Macro-district Cotahuma

Abstract

Landslide mapping is a challenging task as there often is inadequate data about the extent of the hazards and the vulnerability of the local population to these. Considering that many hazards happen in developing countries that have reduced access to monitoring technology, the limitations grow where there is no temporal data on past events. The current study aims to determine the exposure to the landslide hazard, the elements at risk and the vulnerability of the population of Cotahuma macro-district located in La Paz, Bolivia. Given the limitations of data availability, the possibility of producing a very detailed and reliable landslide risk map was impractical; however, this paper proposes a simple method of evaluating the most exposed areas within the district by examining geographical factors that have had an influence in the past, for which data is available. An analysis is carried out to determine landslide risk areas with information from slope characteristics (gradient, aspect, and curvature) and land use, computed using Analytical Hierarchy Process (AHP) and Weighted Overlay Method (WOM) in ArcGIS Pro. To illustrate how a risk map could be useful for management and development in the district, a vulnerability index is created to show which zones within the district are most vulnerable based on accessibility to critical infrastructure. Although the proposed study uses widely available data and a straightforward methodology, the results obtained indicate how it can be improved upon using more current, or higher resolution data. Nevertheless, the initial results produced here provide improved baseline information which could allow the municipality of La Paz to identify appropriate priorities for reducing risk within each district to design a sound hazard mitigation programme.