Review of the occurrences and influencing factors of landslides in the highlands of Ethiopia: With implications for infrastructural development

Abstract

The hilly and mountainous terrains of the highlands of Ethiopia are frequently affected by rainfall-induced landslides of different types and sizes. The major types of landslides reported to have been triggered by heavy rainfalls include debris/earth slides, debris/earth flows and, and medium to large-scale rockslides. Though rockfalls are common in the Ethiopian highlands no association is made with rainfalls. Review of the previous studies revealed that landslide hazards have been causing: loss of human lives, failure of engineering structures, damage on agricultural lands and on the natural environment. Medium to large-scale rockslides were reported in areas underlain by Paleozoic glacial sediments and volcanic rocks. Evaluation of the relationship between landslides and various influencing factors show that the debris/earth slides/flows have prevailed in: (a) areas which are underlain by Paleozoic glacial sediments, shales, and basalt flows, (b) hillslopes characterized by slope angles in the range 15-45 degrees, (c) terrains represented by concave shapes with some on planar surfaces, (d) areas affected by active gully erosion/artificial excavations, and (e) places represented by sparse or no vegetation cover with deeper roots. With regard to the triggering mechanisms, most of the rainfall-induced landslides have taken place in the late periods of the rainy seasons (late August to early September) following heavy rainfalls indicating that process is related to raise in groundwater level coupled with a certain intensity of rainfall event. Ethiopia is currently involved in massive infrastructural development (including roads and railways), urban development and extensive natural resources management. In this whole socio-economic development, landslides and landslide-generated ground failures need to be given due attention in order to reduce losses from such hazards and create safe geoenvironment.

Stability Analysis of Plant-Root-Reinforced Shallow Slopes along Mountainous Road Corridors Based on Numerical Modeling

“…The mechanism through which root-reinforced soil is related to concrete reinforcement mainly plays the role of shear stress and tensile strength effect. The effect of root reinforcement increases the cohesive strength of soil, decreases soil deformation, prevents the incidence of surface tension cracks, and can avoid slope failure initiated by triggering factors [6][7][8][9][10][11][12][13][14][15][16]. The shear stress is developed in the soil and transferred to the ground as tensile resistance in the roots, which ensures mechanical reinforcement by the roots [17][18][19][20][21][22][23][24].…”

“…Earthquake-triggered landslides are rarely reported in Ethiopia. Landslide related hazards are becoming thoughtful concerns to the public and to the planners and decision-makers at various levels of the government [6].…”

Analysis of significance of environmental factors in landslide susceptibility modeling: Case study Jemma drainage network, Ethiopia

“…As mass movement processes are defined as movement of the material down the slope by gravity (Summerfield 1991, p. 167) then with an increase in the slope the gravitational force acting on the slope material will increase as well as the possibility of slope movement. Clerici et al (2002) says that slope is commonly regarded as the most important factor in slope stability, this is supported by researches of Woldearegay (2013) or Broothaerts et al (2012). Land cover is another factor affecting slope stability.…”

Weights of Evidence Modeling for Landslide Susceptibility Mapping of Kabi-Gebro Locality, Gundomeskel area, Central Ethiopia

“…Landslide hazard is a common problem that causes a considerable damage in the highlands of Ethiopia. In many parts of the Ethiopian highlands, landslide hazards are the most destructive natural phenomena which cause property damages, including failures of engineering structures, human sufferings, environmental degradation and loss of fertile agricultural lands (Ayalew 1999;Ayalew 2000;Ayalew et al 2004;Ayenew and Barbieri 2005;Woldearegay 2013).…”

“…Rainfall induced landslides have killed 62 people, injured 30 people, displaced 5091 people from their residence and damage to house and cultivated land in 2018 (Wubalem and Meten 2020). The major intrinsic causes for landslide occurrence in the highland of Ethiopia include geological, geomorphological and hydrogeological factors that are triggered by heavy rainfall (Woldearegay 2013;Ermias et al 2017). Many active landslides exist within the highland of Ethiopia that reactivated by heavy rainfall at the end of august (Ayalew 1999;Woldearegay 2013).…”