Earth Sciences

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Browsing Earth Sciences by Author "Abebe, Bekele (PhD)"

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    Application of Remote Sensing and Geographic Information System (Gis) for Petroleum Exploration in Ogaden Basin: Ethiopia
    (Addis Ababa Universty, 2008-07) Edessa, Beresa; Abebe, Bekele (PhD)
    Petroleum Exploration requires the analysis of different types of data such as satellite imagery, seismic surveys, surface geology studies, subsurface and cross section interpretations and images, well locations, and existing infrastructure information. In this thesis the greatest advantage of Remote Sensing; the synoptic view that it provides, a regional and integrated perspective of interrelations between various land features it gives, the availability of multi-spectral data as well as the advanced capabilities of digital image processing techniques along with the potential of Remote Sensing in generating enhanced and interpretable image is used in delineating the lithological contacts and geological structure in great details with better accuracy than it was. In this thesis GIS is used as a decision support system to demonstrate its with capabilities of efficient data storage and overlay analysis of spatial data from diverse sources, in order to relate all of the data sets (remote ensing, seismic, gravity, geochemical and other ancillary data) to each other, allowing overlying, view, and manipulate the data in the form of a map to thoroughly analyze the potential for understanding or extending play potential in the study area. So With the application of remote sensing and GIS capability, Exploration can be done more accurately, faster, and for less cost. Key words: remote sensing, GIS, gravity, seismic, geochemical
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    Brittle Fracture and Lake Level Change at Beseka:Main Ethiopian Rift, Metehara Area
    (2007-07) Abadi, Berihu; Abebe, Bekele (PhD)
    In early 1960’s, the surface area of Lake Beseka was only 3 km2. In 1976, the lake area was estimated at 27.5 km2 and now it covers around 41km2 (Tamiru et al., 2006). The lake gauge height is about 0.71m in 1976 and 5.6 m in 2006 which almost increased by about 5 m in the last 30 years. The rocks are affected by NNE-SSW faults and fissures. The faults within the area of investigation have very atypical morphologies. Profiles across fissures constructed by Trimble GPS and field observation indicate that the fractures do not show the morphology of typical faults. The footwall remains flat and the concave hanging wall curves up to ward the fault plane. Generally 487 data of edge matching opening direction are taken and weighted according their horizontal displacement to gave the total opening direction 113.4o, which is in agreement with the overall E-W direction. The elevation of water level Lake Beseka is lower than the elevation of water table of wells in the Abadir farm as well as the elevation of Awash River. Hence, the flow of groundwater is towards Lake Beseka. The Abadir Farm- a suger cane plantation south of Beseka-is mainly placed within the lake’s catchment area, which is affected by ground cracks in rainy seasons. The recharge to the groundwater coming from this plantation affects the lake level to rise. In addition to the flow of ground water, the tectonic hot springs as well as cold springs, which are also the main factors to the expansion of the lake, come through these structures in the direction of SSWNNE. The curve of the lake level fluctuation shows an increment with time while climatic data do not show any anomalies. Therefore, climate has not any impact/influence on the lake level rise. The extension of Lake Beseka results with flooding and salinity of Abadir farm land and endangering of the routes (road and railway) from Addis Ababa to Djibouti. The expansion of Lake Beseka has necessitated the raising of the level of the road and railway line repeatedly.
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    Delineation of Food Insecure Areas Using Remote Sensing and Gis (Food Availability Analysis) The Case of South Gondar Zone
    (Addis Ababa Universty, 2014-05) Gedif, Birhanu; Abebe, Bekele (PhD)
    Food insecurity is a matter of both limited food availability and restricted access to food. Food availability is the availability of sufficient quantities of food of appropriate quality, supplied through domestic production or imports. The main objective of this study is delineation of food insecure areas in south Gondar Administrative Zone using remote sensing and GIS from the food availability perspective. The necessary data were generated from satellite images, meteorological data, and other ancillary data. The data analysis technique evolved generation of major factors determining food security. Because there are numerous factors determining food security, the researcher selected cyclic drought and soil erosion as determinant factors from crop production (food availability) perspective. Deviations of NDVI from the long term mean and the Vegetation Condition Index (VCI) derived from SPOT-4 near real time dekadal NDVI images for eight years were used for drought detection. The results were validated using ground truth data such as crop production, food aid beneficiaries and the amount of food aid distributed including the number of stunted and under weight children and pregnant and lactating mothers. The soil loss spot areas through erosion from the study area were estimated using USLE. These two determinant factors were then weighted and overlaid in the ArcGIS environment to generate a map indicating food insecure areas. Of the total areas of the Zone 16.3% is found to be generally food secure, 42.5% moderately food insecure, 32 % highly food insecure and 9.7% is chronically food insecure. The result of the research indicated that food insecure areas can be mapped by ecological boundary, which could be very important during area targeting for food aid and solve the problem under of area targeting using administrative boundaries. In the research it is recommended that delineation of food insecure areas using Remote Sensing and GIS at local level should be encouraged. This system could be scaled up at regional and federal level after incorporating other factors determining food security. In doing so, (1) resource liquidation will be reduced to its optimum level (2) inclusion and exclusion errors for emergency response and or food for work or cash for work will be minimized. Key words: Drought, food insecurity, food availability, Drought detection, Dekade, near real time, inclusion, exclusion, and resource liquidation.
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    Structural Study and its Effect on Thermal activities of Tulu Moye- Gedemsa Area
    (Addis Ababa Universty, 2007-07) Admassu, Engdawork; Abebe, Bekele (PhD)
    The Main Ethiopian Rift (MER) constitutes the northernmost part of the East African Rift System (EARS), connecting the EARS with the Afar triple junction and is an area characterized by active extensional tectonics and associated volcanic activities. The area of investigation, Tulu Moye, is situated in the Main Ethiopian Rift (MER), northwest of Asela, close to the eastern margin of the rift. It is a wide zone where tectonic and volcanic activities are concentrated. The aim of this study is therefore, to show the relationships between extensional structures (normal faults and tensional fissures) and associated volcanic edifices with the aid of Geographic Information System (GIS) for compilation of available geologic, structural and thermal field investigations. By integrating the Landsat images, aerial photographs and topo maps together with the field data the lithology and structures of the study area are mapped with better accuracy, minimum cost and shorter field seasons. Volcano – tectonic data showed a close relationship between dense Quaternary faulting and associated eruptions. Volcanic activity is becoming more recent and young towards the central part of the area (west of the eastern escarpment). Structurally the area is generally characterized by intense quaternary faulting and fracturing. Three set of faults are mapped in the area namely; NE – SW striking marginal normal faults, NW – SE to E – W trending trans-rift faults and the youngest and active NNE – SSW to N – S striking faults of the Wonji Fault Belt (WFB). Almost flat foot wall and hanging wall tilted away from the fault plane is the typical morphology obtained from morphology data collected using Trimble GPS. An approximate E – W direction of extension is obtained from kinematic data collected at two selected sites. Inventory of thermal vents in the area is made using Trimble GPS. The relationship between these thermal sites and tectonics of the area is clearly outlined. In such a way that, the vents follow the general NNE – SSW trend of the intensively and densely populated faults of the Wonji Fault Belt (WFB).