Investigation on Causes of Land Slide in The Blue Nile Basin (Gohatsion-Dejen Road A Case Study)
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Date
2013-07
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Addis Ababa University
Abstract
The Blue Nile basin is severely affected by slope failures. The characteristics of its deep gorges
and rugged valley walls composed of assortment of different geological materials makes the area
legitimate for study. The stretch of main road 3 that passes through the Abay Gorge steeply
climbs nearly 1,500 meters from the bay River to the plateau in 40 kilometer distance. It is
plagued by landslides in the rainy season, especially from June to September, Some of the failure
areas are up to two kilometers wide, putting into jeopardy this vital link road.
Work was commenced with the conception of site reconnaissance and the study area in particular
provides long cliffs of sandstone, limestone, and gypsum intercalated with relatively soft units of
mudstone, shale, and marl. From satellite view also the surface anomalies of the five selected
priority sites shows multi block land slide mass in each station.
Interpretation and analysis of detailed borehole investigation data and different monitoring
devices output data is carried out in order to grasp movements and to find the main slip surface
and the geological structure. Using inverse analysis for the representative landslide blocks the
shear strength parameters of the most probable slip surfaces were determined.
Finally, the study led to the conclusion that the landslides are triggered by rising ground water in
the rainy season. The rising of ground water table is due to infiltration of surface run off.
Therefore, controlling of the infiltration process using different remedial techniques will
minimize the sub surface problem
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Keywords
Land slide, Blue Nile Basin, Goha Tsion-Dejen road