Abstract
This study deals with the development of a Geographic Information System (GIS)-based geotechnical microzonation model/map using Analytic Hierarchy Process (AHP) for Shire-Endasilasie, a rapidly growing city in Tigray, northern Ethiopia. The influencing factors considered as inputs for the development of the model are (i) slope gradient, (ii) bed rock and soil type, (iii) swelling potential of soil and (iv) depth to groundwater level. The factors and the classes within each factor are assigned weight and rank values respectively. To avoid subjectivity, the assignment of weight and rank values and the analysis are done by the application of AHP method. From the weight and rank values of the layers, geotechnical suitability indices were calculated using a Weighted Linear Combination (WLC) model in GIS. These continuous numerical index values have been divided into different classes. The classification result implies that the less suitable zone represents the areas that require a detailed geotechnical investigation, the moderately suitable zone represents a provisional settlement area, and the suitable zone represents the areas that are best suitable for settlement. Keywords : GIS, Analytic Hierarchy Process; Geotechnical microzonation model; Foundation, Shire-Endasilasie,Tigray, Ethiopia.
Highlights
Shire-Endasilasie is one of the rapidly growing cities in Tigray region, northern Ethiopia and currently the construction work is being undertaken in a big way in all directions of the city
People are moving to the hillsides and previous farm lands on the city sides and are constructing several residential buildings without going through the planning stage and without undertaking evaluation of geological and geotechnical factors which is essential to determine the suitability of the foundation of residential areas (Khizar, 2003)
It is stated that the areas where the settlements are high and dense prior to geotechnical evaluation, preparation of geotechnical microzonation model helps to check the suitability of the area for such density and to determine the precautions that are needed for safer planning actions or modifications
Summary
Shire-Endasilasie is one of the rapidly growing cities in Tigray region, northern Ethiopia and currently the construction work is being undertaken in a big way in all directions of the city. The present paper proposes a geotechnical microzonation model for ShireEndasilasie city using GIS-based multi-criteria decision analysis ( AHP). Topology and climate Shire-Endasilasie city is located in the northwestern zone of Tigray Regional State, northern Ethiopia (Fig1) and geographically it is bounded between 14°04'55"N to 14°07'00"N latitude, and38°15'30"E to 38°19'00"E longitude. It covers an area of about 21.6sq.km.The topography of the study area is mainly flat in the central part, bounded by large hills in the northern part, small hills in the southern and western parts, and river in the eastern part of the city (Fig 2). The sandstone consists of intercalations of sandstone and siliceous mudstone with thin lateritic cover, and is correlated with the Adigrat Sandstone (Tarekegn, 1997)
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