Landslide susceptibility assessment of Calabar, Nigeria using Geotechnical, Remote Sensing and Multi-Criteria Decision Analysis: Implications for urban planning and development

Abstract

This research was carried out to delineate zones of high likelihood of landslide occurrence in view of the fatal incidence of September 2013 that buried a building and 9 occupants in the city area of Edim Otop. Method involved field geotechnical boring and laboratory analysis; remote sensing analysis of SRTM-(DEM) and Landsat ETM imageries to extract slope and aspect; land use land cover, drainage and normalized vegetation index. The zonation of landslide susceptible areas was implemented using analytic hierarchy process (AHP) in a multi criteria decision analysis of factors important in landslide occurrence. Results of the AHP depicts that the ground slope contributes 32% to the likelihood of landslide occurrence, while the orientation of the slope (aspect), soil type, cohesion, friction angle, hydraulic conductivity, drainage, land use land cover and normalized vegetation index's causative abilities to slope instability, failure and landslide susceptibility were 22%, 16%, 9%, 7%, 6%, 3%, 3%, and 2% respectively. Three landslide susceptibility zones of low, high and very high landslide susceptibility have been delineated. The ten deep gully sites sampled during the field studies all fall under the zone of very high land slide susceptibility including Edim Otop, the site of the September 2013 fatal rainfall induced incidence. Recommendations for management include risk and hazard quantification considering human occupation on very high landslide susceptibility areas, slope protection methods including excavated sections, use of sites of previous landslide such as Edim Otop as pilot projects to characterize the mechanism of slope instability and back analysis of slope failure as reference.

Landslide Zone Investigation by Determining Cracks and Cracks Compressive Strength Test in Waru District, Pamekasan Regency

“…If the cracks accumulate by water, it will be very dangerous because the load will get heavier below the surface which at any time can trigger landslides [9] . Three landslide susceptibility zones, namely low, high, and very high landslide susceptibility, have been described, landslide zones that result in very high landslide vulnerability due to rainfall [16] . Shallow landslides due to rain are the main landslide type occurring on the natural plains of Hong Kong due to the high seasonal rainfall and the soil profile that is resistant to deep weather [17] .…”

Seasonal Variation in Abundance, Distribution and Environmental Impacts of Geomicrobiological Communities in the Lower Calabar River Channel, Calabar, Nigeria

“…The geotectonic evolution and regime is the same as that of the Niger Delta and Benue trough, Nigeria [22]. The Calabar flank is a hinge line bordering the East-South-East limit of the Niger Delta basin.…”

Landslide susceptibility mapping using frequency ratio model: the case of Gamo highland, South Ethiopia

“…2c, f). It is a major factor for slope instability and landslide as a higher slope angle equates to higher shear stress and a greater tendency to fail if the materials are soil and weak rocks (Abija et al 2019). In this study, slope gradient was classified into five classes.…”