Landslide Susceptibility Mapping and Risk Assessment on the Bamenda Mountain (Cameroon Volcanic Line)

Guedjeo C S,Wilson Buma G,Wotchoko P,Kamgang K V,Chenyi M L,Nkouathio D G,Kagou Dongmo A

doi:10.12691/jgg-5-4-2

Abstract

The Bamenda Mountain (with over 250,000 inhabitants) is one of the strato-volcanoes along the Cameroon Volcanic Line (CVL) with an accidental landscape. This area is frequently affected by landslides, which most at times result in destruction of property and loss of lives. An informative value statistical method using GIS is use to prepared a landslide susceptibility map for the Bamenda Mountain area as well as a quantitative and qualitative risk assessment. This is aimed at revealing areas where future landslide would occur and potential loss. Nine landslide controlling factors including; slope, slope orientation (aspect), curvature, stream density, proximity to roads, geomorphology, proximity to streams, geology and land use were use in the model. A total of 64 slides were inventoried in the area and use to prepare the landslide density map. The weighted informative values for the combined factor and landslide density were used to prepare the landslide susceptibility map for the area. The most significant landslide causing factors in this area are; slope, stream density and slope aspect. The susceptibility map was classified into very high (17.8%), high (25.9%), moderate (33.6%) and low (22.7%). The validated model using the success rate curve indicates that the area under curve is 0.823 and predicts landslides at 82.3% in relatively high classes. Landslide risk assessment in the area indicates 406 buildings, 2,436 people, 1,291.1km of roads, 2152 ha of farmland and an approximate USD83,540,000 worth in assets are expose to high and very high risk. This approach can be implemented in other areas along the CVL to map and assess landslide risk.

Highlights

Landslides occur predominantly on slopes where the soils shear stress exceeds its strength
Landslide conditioning factors selected for susceptibility mapping on the Bamenda Mountain were functional and operational and were similar to those used by [4,16,30] in susceptibility mapping along the Cameroon Volcanic Line (CVL)
This classification is based on the level of quantification dividing the landslide risk assessment methods into: (1) Qualitative methods, (2) Semi-quantitative methods, and (3) Quantitative methods

Summary

Introduction

Landslides occur predominantly on slopes where the soils shear stress exceeds its strength. These landslides are usually triggered by high rainfall or earthquakes. The global trend on landslide fatalities has been on the rise in the past decade. In 2016, the landslide fatalities increase further to 620 mortality. With the rise in global population following technological advancements, settlements along mountain slopes has increase drastically, thereby increasing the vulnerability in these zones. Though landslides have been widely studied, it still poses problems in susceptibility, risk mapping and assessment. Different types of landslide hazard mapping techniques have been developed over the last decades [6,32,43,53,59,61]

Methods

Results

Discussion

Conclusion