|Title: ||Mass movement mapping for geomorphological understanding and sustainable development: Tigray, Ethiopia|
|Authors: ||Moeyersons, Jan ×|
Van Den Eeckhaut, Miet
Van de Wauw, J
Deckers, Jozef A.
Mitiku, Haile #
|Issue Date: ||Sep-2008 |
|Series Title: ||Catena vol:75 issue:1 pages:45-54|
|Abstract: ||Mass movement topography characterises the escarpments and piedmont zones of the tabular ridges in the
western part of the Mekelle outlier, Tigray, Ethiopia. Several types of mass movements can be distinguished.
The first type is rockfall produced by 357 km rocky escarpments and cliffs during the rainy season. In the
study area, every current kilometer of Amba Aradam sandstone cliff annually produces 3.7 m3 of rock
fragments. However, this is an under-estimation of the actual cliff and escarpment evolution, which is also
characterised by debris slides and small rock slides.
In the debris flow class, three dormant flow types are recognised. The first type comprises preferential or
undifferentiated mobilisations of the so-called plateau layers, the whitish sandy-clayey lacustrine deposits
and the lower and upper basalts, and more especially, the swelling clays, derived from the basalts. These
debris flows start on the nearly horizontal Amba Aradam Sandstone tabular extensions, jump over cliff
recessions or even spurs, and go very far into the valley. In some instances parts of Amba Aradam sandstone
and Antalo limestone cliffs are transported. Secondly, some debris flows take their origin in the Antalo
limestone supersequence. It concerns deeply weathered layers resting upon aquicludes/aquitards. Finally,
gigantic debris flows and rock slides occur around dolerite dyke ridges.
About 20% of the total surface of the study area is occupied by landslide topography. Most of the landslides
affect the steep edges of the table mountains or the dykes/sills.
Mapping and listing of active and dormant mass movements increases knowledge in three domains which
are crucial for sustainable development of the study area. The first one is geomorphological risk assessment.
The distribution map of active rockfall and dormant landslides shows the areas where potential risks are
located. Land use changes which improve the water infiltration capacity of dormant landslides, should be
followed up. Secondly, the impact of global climate change on these risk areas can be assessed. The second
domain is the water sector, which needs attention in the study area and in many parts of Africa. Landslides
mobilised by hydrostatic pressures are related to the occurrence of aquicludes and aquifers. In the study area,
landslide mapping led to the location of three aquitards, not described before. The third domain is the
pedological mapping. In the study area, soil distribution is very well explained by the morphology and
extension of dormant landslides.
Finally, mapping of dormant landslides stimulates the academic debate on the geomorphological significance
of mass movements in hillslope retreat in tropical areas.
|Publication status: ||published|
|KU Leuven publication type: ||IT|
|Appears in Collections:||Division of Geography & Tourism|
Division Soil and Water Management