THE GEOGRAPHIA : DESSIE BASIN, ETHIOPIA - THE MOTHER OF LANDSLIDES

Severe rainfall has been reported as the major cause for innumerable slope movements in the highlands and around the margins of the main rift valley of Ethiopia. The study area in this project includes the Dessie town situated in the northern highlands of Ethiopia. It is one of the most frequently affected towns by a landslide in the past several years. During July and August 2010 rainy season alone, it has been reported that 37 people were dead in this town, and their houses damaged because of intense rainfall and subsequent flooding and landslides. In addition, many bridges and roads (including the main road connecting the town with the surrounding regions) and other infrastructures were destroyed and an extensive mass of agricultural land devastated further north and south.

Dessie town where almost all town's geological condition is to shinking towards the mother of landslide

Dessie basin and town is an ideal place for both the theoretical and practical aspects of the Landslide understanding. This town is a home for above 205,000 inhabitants who live where there is a potential danger of landslide to occur. The 'Landsldie Mapping' training provided us the ability to identify areas susceptible to landslide and to map such areas. Although most of possible mitigations to landslide are expensive, we are able to know how the technical aspects can be implemented. We also recommend for establishment of office (advisory service) at Dessie town to provide technical information about the near future effects of landslide to administrators and people leaving in the area to protect residents.

Group photography in the front of shinking site

In the background - Mother of landslide in Dessie town

A horizontal movement (landslide) scene in Dessie town

Verifying that how horizontal landslide broke the wall beside the river

Walking along the top of the mother of landslide in Dessie town

Giving instructions during the field work by Prof. Giando

The aim of the LANDMAP Dessie Excursion was to describe the landscape of Ethiopian plateau and mass movement in the Dessie area, to map and to interpret field observations in ArcGIS 9.3 within the context of sustainable hazard mitigation. Dessie landslide mapping and characterizing landslides and landforms associated with tectonic and fluvial landscapes. Through Dessie landsliding excursion we able to understand the field based methods of identifying and classifying landslides and landforms associated with fluvial, lacustrine and hillslope processes. Before going in the field study we properly understood it through aerial photographic interpretation and analysis and mapping geomorphological features using Geographical Information Systems (GIS). Practical training was complimented by theoretical lectures relating to processes and drivers of landslide development and dynamics from experts in the field of landslide geomorphology, Giandomenico Fubelli (Prof. from Roma University, Italy) and Jan Moeyersons (Geomorphologists, Royal Museum, Portugal).

We spent several days exploring the surroundings of Dessie, mapping landslides, fault scarps, terraces, alluvial fans and a number of other landforms. This was a great experience for me as I have never been in a graben, and a number of the landforms were new to me. Spending time in the field with the specialists taught me a lot about landscape interpretation and how to represent it accurately on a map.

Almost all Dessie town is shinking towards mother of landslide site

Mother of Landslide in Dessie town

There was a lot of focus on the subtle differences between the various types of landslides, possible triggers and how they can be avoided. The mapping part of the exercise was challenging at times; looking at stereo aerial photographs, interpreting what was seen and what was noted in the field and transferring it accurately into a GIS. The exposure to open source GIS software was encouraging as it was just as effective, maybe even more user friendly than commercial packages.

Different types of Landslides

Different types of landslide

Different kind of landslide, which we seen in Dessie town during the field work

Landslide Mapping team enquiry about horizontal movement (creep) on the surface

A broader view of the piedmont of the river just came down from the area of the mother of landslide

Mother of landslide view in the background (also Dessie lacustrine deposits is visible with river)

Verifying the mother of landslide (top portion) by Landslide mapping team

During the field work in Dessie town (lateral slide)

Making an understanding over a gully development due to horizontal shifting (block slide) of the surface

Taking an overview over Dessie landslide (translational) area by our team

Cracks in the wall of a building is proof that horizontal movement (creeping) on the surface is going on

Horizontal movement in the surface resultant on the large level slope movement (creeping) in the foothills region

We would like to thank to International Association of Geomorphology (IAG) for sponsoring us to attend the training on Intensive Course on Landslide Geomorphology and Mapping (LANDMAP) and participate in the IAG Regional Conference in Addis Ababa, Ethiopia. We thank also to Prof. Giandomenico Fubelli and Prof. Jan Moeyersons for their unreserved and dedicated lectures in class and fields on the Landslide Geomorphology and Mapping. Thus, We appreciate for those who select Dessie town to be the place for the course to be carried out.