Earth Sciences
Permanent URI for this collection
Browse
Recent Submissions
Item Comparative Analysis of Urban Expansion on Lst and Vegetation Conditions of the City Environs Using Remote Sensing Technology a Case of three Cities in Ethiopia(Addis Ababa University, 2023-06) Peniel Wacktola; Biniyam Tesfaw; K. V. SuryabhagavanPopulation growth has been followed with urbanisation for the past 50 years and this urbanization has impacts on the environment like Land Surface Temperature and vegetation conditions on the urban areas. Therefore, this research aims to evaluate how land use patterns have changed over the past 19 years in three cities and how those changes have affected vegetation and land surface temperature (LST). Satellite images such as Landsat ETM+ (2003 and 2013), Landsat 8 OLI/TIRS (2022) and ASTER night time image were used as geospatial data to extract the Environmental variables (Land Use Land Cover, Normalized Difference Vegetation Index - NDVI, Normalized Difference Built-up Index - NDBI, and LST). Split window algorithm was the method to calculate LST. The result shows that LULC has a decrease change in agricultural areas and increment of built-up areas for the three cities during the study periods. The study indicated that areas having lower LST in 2003 (mean LST = 9.13 oC , 17.63 oC, and 12.80 oC ) were changed to higher LST in 2022 (mean LST = 12.19 oC, 21.97 oC, and 17.60 oC)in Addis Ababa, Adama and Hawassa, respectively. Also, the vegetation cover decreases from 25005.78 ha, 7801.48 ha, and 13489.92 ha in 2003 to 13394.23 ha, 3462.16 ha and 6633.87 ha in 2022 in the three cities, respectively. The mean of NDBI in 2003 (Addis Ababa=0.02, Adama=−0.01 and Hawassa =−0.03) and increases to 0.17 in Addis Ababa, 0.11 in Adama and 0.08 in Hawassa for the year 2022. The correlation result (Year 2022) shows that NDBI (Built-up) has a positive correlation (R=0.89, R=0.87 and R=0.91) with LST and a negative correlation (R=-0.62, R=-0.77, and R=-0.86) with NDVI (vegetation) for Addis Ababa, Adama, and Hawassa, respectively. This result gives an insight to Environmental experts and organizations to reduce the impacts of urbanization on the LST and Vegetation in cities and surrounding areas. This study also demonstrated that geospatial tools and methodologies may provide quick and accurate results for analysing environmental variables and change at the regional scale.Item Petro-Chemical Characterization of Basement Plutonic Rocks and Associated Volcanic Outcrops in Homosha-Kurmuk Area, Western Ethiopia(Addis Ababa University, 2023-05) Asedik Alesa; Sofia AbdulkadirThe primary objective of this study was to characterize the petrography and geochemistry of the rocks in the study area with the goal to determine the classification of the lithological units that were discovered there. Field investigation, petrographic study, and a complete silicate geochemical analysis were done for this aim. According to the petrographic findings, the primary components of the rock units in the research region are quartz, plagioclase, k-feldspar, olivine, pyroxenes, biotite, hornblende, and opaque minerals. According to the TAS classification, the geochemical findings identified the rock units in the research region as granite, basalt, rhyolite, and diorite. Additionally, it placed the mafic/basaltic samples in the tholeiitic series on AFM and the felsic samples in the calc-alkaline series. The rock units in the studied area are thought to have formed as a result of fractional crystallization combined with crustal contamination, according to the Harker variation diagram of the major oxides versus SiO2. This fact is demonstrated by the fact that while the concentration of the major oxides like Na2O and K2O displays an increasing pattern with the increasing SiO2 concentration, the concentration of the major oxides like TiO2, Al2O3, MgO, CaO, P2O5 and FeOt decreases with the increasing concentration of SiO2. The granites are determined to be of post-tectonic origion at continental arcs while the basalts are determined to be of subduction zones.Item Land Use Land Cover Change and its Impact on Major Nutrients and Macroinvertebrate Along Wabe-Megecha Rivers Sub-Catchments Gibe-Omo Catchment Ethiopia(Addis Ababa University, 2023-02) Abel Feyisa; Tadesse FetahiRivers are a major aquatic ecosystems that are rich in the biological community and characterized by nutrient dynamics playing a major role in connecting terrestrial and other aquatic ecosystems. These ecosystems provide crucial services including fish production, water provisioning, recreation, water purification, water retention, and climate regulation. However, these life-sustaining ecosystem are deteriorating due to anthropogenic activities including pollution, overexploitation and land use land cover (LULC) change. The latter affects the nutrient contents and biodiversity such as macroinvertebrate community structure, abundance and function. These changes affect the integrity and health of an ecosystem, which is evident in Ethiopia such as the Wabe-Megecha river catchment. Correspondingly, this study aims to investigate the pattern of LULC, the nutrient concentrations (N and P), and macroinvertebrate change with LULC types along the Wabe-Megecha River sub-catchment. The study was conducted at 12 sampling sites of four streams from May to June 2022. The global land use land cover dataset includes a 10m high-resolution Sentinel image for the years 2018 to 2021 was used for the change detection. Water and macroinvertebrate sampling was done for the nutrient analysis, and macroinvertebrate composition, respectively, along the different land uses, from 4 selected sites. The LULC change data was reduced and calculated to the specified study area using Arc-GIS software version 10.4. Statistical tests were done at 0.05 significance levels using SPSS V.26, Past4Project, and Rx64 v. 4.1.2 in R-studio. The result shows that there has been a dynamic of LULC between 2018 and 2021. The expansion of agricultural land and settlement was notable. While the conversion of natural riverine forests to Eucalyptus plantations is stabilizing the forest cover, but degrading the natural environment and thus biodiversity. Most nutrients and physicochemical variables showed significant differences (ANOVA, p < 0.05) among the sampled sites. The urban, agriculture and livestock (UAGL) impacted site had significantly (p < 0.05) higher nutrient concentrations compared to the other land uses. A total of 6,009 specimens from 9 orders and 29 families were sampled at 12 sites in 4 streams within the Wabe-Megecha catchment. Order Ephemeroptera, Diptera, and Odonata had the highest number of families each representing a total of six families. The highest number of individuals was recorded in Agriculture dominated (AGR) site while the lowest abundance was recorded in the site dominated by the combined effect of urban sewage, agricultural activities, and livestock (UAGL). Order Diptera was the most abundant order among sites which is recoded in the same number in all land uses except Urban, agriculture, and livestock (UAGL) which is highly polluted from all kinds of impacts. Land use change from forest to agriculture was seen to be a major driver of changes in physicochemical water parameters and habitat quality, which also significantly influenced the diversity and distribution of macroinvertebrate taxa. This work highlights the need to conserve forested areas and riparian zones to preserve the ecological integrity and functioning of the Wabe-Megecha River. Thus, efforts are needed to manage the catchment through a well-integrated catchment management for the sustainable utilization of the resources.Item Identification of Thermal Groundwater Zones Using Hydrogeochemical Approach in Case of Akaki River Catchment(Addis Ababa University, 2022-12) Behailu Girma; Tilahun AzagegnEthiopia is gifted with many different thermal groundwaters and hot spring resources which are located in various physiographic, climatical, and geologic settings. The filwoha springs had been served as the source of thermal waters for many decades. An attempt was made to zone and identify thermal groundwater in the akaki river catchment through assement of thermal wells and distinguishing the geological and structural setup of the area. The study area is located in the awash river basin. Adminstratively, the area is situated within addis ababa city and finfinne specila zone of oromia regional state. Fourty four (44) boreholes were inventoried to delineate thermal groundwater areas of akaki river catchment. Temperature of the inventoried wells ranges from 37°c to 86°c. The tds measurement range between 230 to 2528mg/l. The thermal boreholes depth varies from 56.4 to 583.50 meter. Geologically, the area is characterized by secondary structures which are mainly related to extensional tectonics responsible for rift formation and volcanic activity. The thermal groundwater in the study area is characterized by higher TDS, EC, Na+, and F-; and lower concentration of ca concentration Both the tds and ec concentrations decrease in all directions away from the epicenter of the filwoha zone. The lowest concentration of TDS and EC in thermal water is recorded in southern area thermal groundwater with tds and ec values range from 280 mg/l to 378mg/l and 467 mg/l to 589 mg/l respectively. The thermal water in north western part of the study area around filwoha is substantially hot and it can reach up to 86 oC as it is observed at legahare well. In the eastern part of the study area, the thermal groundwater varies from 38 oC to 50 oC. The thermal groundwater in southern part of the study area is comparatively lower than the two areas and has a maximum value of 48 oC. The groundwater temperature versus depth of well plot show that the temperature of thermal water has a positive linear correlation with the depth of the boreholes.Item Stratigrphy and Petrography of Flood Basalt Succession at Debre Libanos Area Central Ethiopia(Addis Ababa University, 2022-12) Kuri Yimenu; Dereje AyalewThe study area is located in the Northwest Shewa, Oromia Regional State with in NW Ethiopian Plateau, specifically around Debre Libanos, in central Ethiopia, about 105 km, in the northwest of Addis Ababa. The studied stratigraphic successions are cut by Zega wedem River. The main objective of the study is to constrain stratigraphy and Petrography of flood basalt succession at Debre Libanos area. To accomplish the objectives, starting from the beginning various methods have been applied. The methods are; Literature review, field work, and petrographic (thin section) analysis of representative samples. A total of 18 petrographic samples from these stratigraphic units are studied by using a petrographic microscope. From field and petrographic perspective, the area comprises the major lava flows identified in this study are; Aphyric basalt, plagioclase-olivine phyric basalt, plagioclase phyric basalt, ignimbrite, plagioclase-olivine-pyroxene phyric basalt and olivine-plagioclase phyric basalt. The volcanic units are underlain by Mesozoic Sandstone formation. The basaltic lava flows are the dominant product with interlayered pyroclastic deposits. The majority of the samples are from Basaltic units and have a variety of textures ranging from aphyric to phyric to mildly porphyritic. Plagioclase and Olivine are the major phenocryst phases with a proportion of pyroxene and Fe-Ti-oxides. In some samples, the groundmass is made of microlites of the same phase with a glassy texture. This distinctive petrographic heterogeneity reveals difference in depth of fractionation and magma flux in the lithosphere. The presence of olivine-plagioclase-pyroxene phyric basalt indicates there is considerable depth of fractionation in the shallow plumbing system. The aphyric basalt flow unit reflects there is no fractionation of any mineral in the shallow crust this indicates that the rate of magma flux to the shallow plumbing system is high.Item Application of Integrated Geophysical Methods to Map Geological Structure and Characterize Groundwater Aquifers in Meki Area East Shewa Zone(Addis Ababa University, 2023-05) Ephrem Alemu; Mebatseyon Shawel; Tilahun AzagegnGroundwater is the water found beneath the Earth's surface at depths where the soil, sediments, or rock are totally filled with water. This study focuses on mapping geologic structure and characterization of the groundwater aquifers of Meki to Alemtena area. The magnetic and electrical resistivity methods of prospecting give an effective presentation of the subsurface structures and delineation of groundwater aquifers. Aquifer characterization is essential for managing water resources. The interpretation of VES gives five to seven layers across all the three profiles with the average aquifer thickness of approximately 30 to 70 m. Fractured ignimbrite, sand, and alluvial deposit make up the lithologic unit of the aquifer layer, which is severely weathered and fractured. Protective capacity of aquifers with in the area is in the range of moderate to good. In terms of aquifers water potential, the areas of high longitudinal conductance, high transmissivity, low transverse resistance, low longitudinal resistivity shows the areas of high groundwater aquifers. Based on these, the study area has the highest groundwater potential in the northwestern part. Similarly, magnetic result shows that the lithological trend running from NE – SW along the research area's sides to the north and south as well as deep structures that follow the E-W trend. The groundwater flow direction to the south and north of the survey region may be determined by this structure. Most anomaly sources in the research region related to deep structures, as determined by 3D Euler deconvolution and a 2D magnetic model. The results are combined to produce a comprehensive representation of the subsurface groundwater, structures and hydrogeology. Integration of method's offers more detailed information on the aquifer characteristics, groundwater potential and identification of various lithologic structures in the area.Item Geology Physicochemical Characterizations and Possible Industrial Use of Tegora Silica Sand Occurrence in the Abay Basin Central Ethiopia(Addis Ababa University, 2023-06) Hussien Yessuf; Worash GetanehSilica sand is the second most dominant mineral in the earth’s crust and the most often used technical term for sand or sandstone that easily disintegrates and contains a substantial amount of silicic acid (quartz grains). The Tegora silica sand occurrence is situated in the upper parts of the Abay basin, central Ethiopia, about 229 and 180 kilometers north of Addis Ababa and Debre Berhan respectively. Geologically, the deposit area is composed of Mesozoic age clastic to marine sedimentary successions that are unconformably overlain by thick Cenozoic volcanic rocks, such as limestone, mudstone, basalt, and sandstone in which silica sand is hosted. The main goal of the research is to investigate the geology, physicochemical characteristics, and possible industrial use of Tegora silica sand occurrence. To conduct this, field observation, and analytical investigation activities were applied. The Tegora industrial sand resource is dominantly found as light grey to white, poorly-consolidated sand layers interspersed with siltstone and conglomeratic beds, as the onsite investigation shows. Findings from the sieve analyses, the investigated quartz sand resource is described by the majority of sand-size grains (avg. 96.40%) with lesser amounts of gravel (avg.1.247%) and mud (avg.2.367%) size particles The dominant sand grains reveal an angular to sub-angular and less spherical shape. Complete silicate analysis reveals that silicon dioxide (SiO2) forms the abundant metal oxide in the entire samples with an average quantity of 92.25%, followed by (Al2O3=6.45%), (Fe2O3 =0.63%), (K2O=0.3%), (TiO2= 0.17%), (Na2O= 0.11%), (P2O5= 0.08%), (MgO=0.05%), and trace amounts of CaO, MnO, and Cr2O3. The mineralogical analyses on silica sand with the XRD method implied that quartz, kaolinite, feldspar, and tridymite show the most diffraction picks, and quartz (SiO2), which revealed a high phase average percentage proportion of above 80%, is the major crystalline component of the Tegora silica sand samples. Resource estimation and classification explained researched area has about 4.22 billion tons of quartz sand deposit in an indicated resource class. Based on Ethiopia’s present yearly industrial sand consumption (84.5 million tons), it can continuously extract for 50 years. Geological and physicochemical characteristics analysis shows that the silica sand resource from the Tegora area can be used for filter media, abrasive, foundry, and cement industries. Furthermore, with the beneficiation of the deposit, the upgrade silica sand is utilized for high-grade glass and ceramic sectorsItem Slope Stability Assessment for Sego Dam Site Southern Ethiopia(Addis Ababa University, 2023-05) Mehari Gebremeskel; Trufat HailemariamA thorough evaluation of slope stability was carried out at specific critical sections of the Sego dam and irrigation project site in southern Ethiopia. The identification of these critical areas and the determination of their geotechnical characteristics involved an extensive field survey, which included on-site testing, sample collection, and laboratory analysis. Various measurements were taken during the field survey, including slope geometries, orientation of discontinuities, and in-situ Schmidt hammer rebound tests. Additionally, sampling was conducted. Subsequently, stability analyses were conducted using both kinematic and deterministic methods. Thorough assessments were performed to examine the stability of possible unstable slopes, employing deterministic methods. The analysis encompassed evaluating the stability of critical slope sections under varying water saturation conditions, both in static and dynamic scenarios. Data regarding structural discontinuities, the Geomechanics (RMR) rock mass classification system, and slope geometry were incorporated into the calculations for determining the FOS. The SHRV test provided a range of values for the point load index and UCS, from 4.2 MPa to 9.06 MPa and 68 MPa to 106 MPa, respectively. Additionally, the RQD and RMR values spanned from 42 to 75 and 35 to 69, respectively. Analysis of the rock mass rating system indicated that slope sections L-SS-2 and R-SS-3 had favorable rock quality, while L-SS-1, R-SS-1, and R-SS-2 exhibited poor quality. Similarly, markland test conducted by DIPS.7 revealed potential wedge and planar modes of failure in L-SS-2 and R-SS-3, as well as L-SS-1, R-SS-1, and R-SS-3, respectively. Under dynamic saturated conditions, all critical rock slopes, except R-SS-3, exhibited greater instability compared to static dry conditions, particularly when subjected to seismic loads. These findings suggested that assuming full saturation and seismic loading rendered the slopes unstable. Consequently, a sensitivity analysis of the governing parameters for slope stability was performed, and appropriate remedial measures were proposed.Item Aquifer Characterizations of Big- Akaki River Catchment (Central Ethiopia)(Addis Ababa University, 2022-06) Wasihun Kibret; Telahun AzagegnThe study area covers (big akaki) that situated in upper awash basins and it is part ofsubakaki river catchment, akaki catchment has massive drainage system mainly composed of Big and Small Akaki River. The two rivers meet at the man- made reservoir called Aba Samuel reservoir. The Akaki River gauged at Akaki Bridge and flows to Awash River. The study asses the Groundwater system of big akaki catchment using different approaches by estimating groundwater recharge, characterizing the groundwater system based on the hydraulic properties, ground water occurrence and hydro geochemical signature. The precipitation conditions of the area show bimodal rainfall type. The groundwater system and aquifer characterized based on hydraulic parameters and pump testing results (transmissivity, hydraulic properties, specific capacity, safe yield, water level, drawdown, depth variation and aquifer thickness to evaluate aquifer system of the investigation area. Hence, the transmissivity and hydraulic conductivity is maximum at akaki and legetafo well fields while lower or minimum at central western of the catchment. Additionally groundwater occurrence of the catchment classifying based on intergranular and fissured aquifer. Highly productive intergranular aquifer contains chefe donsa phyroclastic and alluvial sediments while fissured aquifer unit is mostly Addis Ababa basalt , Addis Ababa ignimbrite and entoto becho rhyolitic rock units. The aquifer system also classified based on productivity nature in which highly productive, moderate and low productive zones of the aquifer catchment identified. The hydrochemical signature of the catchment characterized based on spatial variations of anions and cations, hydrochemical facies, water type and chemical evolution entire catchment. Aquifer characterization described as the process of evaluating the transport characteristics and chemistry of aquifers. The study area is part of rift volcanic margin and covered by different geological sequence especially volcanic rocks like basalt, rhyolites, ignimbrite, tracky basalt and volcanic deposition. These above listed lithologies mainly occurred as on both the surface out crop and forming subsurface volcanic strata and used as ground water reservoir of subsurface aquifer. Dominantly the ground water system of the study area may transmitted through interconnected spaces that make the regional ground water flow, this is due to the highly porous and permeable formations and structures found (fault, joints, lineaments and fractures) .That the area is part of the rift system, which is tectonically active to produce different geological structure.Item 3-D Inversion of Gravity and Magnetic Data to Study the Crustal Structure and Depth to the Moho of the Central Main Ethiopian Rift(Addis Ababa University, 2022-06) Denberu Besfat; Abera Alemu3-D inversion of gravity and magnetic data is a powerful method for predicting geology beneath the surface through quantitative interpretation of the geophysical problem at hand. 3-D inversion of these two potential field methods increases the amount of information that can be extracted from the observed gravity and magnetic data. The ultimate goal of this MSc thesis is to implement 3-D inversions of airborne gravity and ground magnetic data. Accordingly, 3-D inversions of airborne gravity data collected with an 8 miles’ line interval for geodetic purposes (2006-2007) and magnetic data collected by the researcher along with existing magnetic data collected by previous MSc students of AAU have been used to study the crustal structure and determine the depth to Moho of the central part of the Main Ethiopian Rift (CMER) and adjacent plateaus. The analysis of the isostatic gravity anomaly and the 3-D gravity inversion had helped to compute and compile the depth to Moho map of the study area (CMER). Consequently, the crust beneath the rift floor was found to be thin and shallow (36-38km) while the crust beneath the South Western (SW) and South Eastern (SE) plateau regions is found to be thick and deep (38-44 km). Moreover, the 3-D gravity inversion and the analysis of isostatic anomalies had revealed that the crust beneath the rift floor is associated with positive density contrasts caused by magmatic intrusions intruding the crust over this region while the crust beneath the SW and SE plateau regions is associated with negative density contrasts indicating the crust beneath the plateau regions is embedded in to a high density mantle material and hence producing a negative density contrasts. The 3-D gravity and magnetic inversion in this MSc thesis work has finally produced 3-D subsurface density and susceptibility models of the study area (CMER). The principal inherent non-uniqueness problems faced with the inversion of gravity and magnetic data that exist based upon a static potential field were attempted to be constrained through incorporating as little information as obtained from previous studies and through by carefully designing a global objective function. This MSc thesis illustrates how the University of British Columbia Geophysical Inversion Facility (UBC–GIF) 3-D gravity and magnetic inversion codes can be applied to study crustal structure by establishing the necessary results. Henceforth, the 3-D inversion executed in this MSc thesis is the UBC-GIF’s inversion methodology which is 3-D regularized pixel-based algorithm proposed by LI and OLDENBURG (1996, 1998) where right rectangular prisms are used to define unknown density and susceptibility model parameters and the solution to the inverse problem is obtained by posing the inverse problem as a mathematical optimization process.Item Groundwater Potential Assessment and Hydrogeochemistry of Upper Dhungeta and Ramis Sub-Watersheds, in Case of Oromia Regional State, West Hararghe Zone, Ethiopia(Addis Ababa University, 2022-12) Zelalem Zerihun; Tilahun AzagegnThe main sources of water for domestic water supply of Bedesa, Gelemso, kara, wachu towns, Boke woredas and neighboring rural villages is Upper Dhungeta and Ramis Sub-watersheds where are found in the eastern escarpment of the rift valley on the upper part of Wabishebele river basin. Despite their importance, the hydrogeological and hydro geochemical system of the sub-watersheds is not well understood. This study was aimed to assess the groundwater resource potential and Hydrogeochemistry by identifying and characterizing the main aquifer types of the sub-watersheds, estimating the natural groundwater recharge, determining ground water flow directions, identifying geochemical evolution and suitability of the water in the sub-watersheds for different purposes. Well log data and hydraulic parameter values obtained from constant pumping test data were used to identify and characterize the aquifers in the sub-watersheds. For estimation of the natural groundwater recharge, soil water balance method was used. Groundwater flow directions also were determined from the groundwater contour map prepared by GIS software using groundwater level data. The study has indicated that there are three major types of aquifer types in the sub-watersheds namely Extensive and Moderately Productive Porous Aquifers, Extensive and Highly Productive Fissured Aquifers and Extensive and Moderately Productive Fissured Aquifer. From the computed meteorological data, the amount of water infiltrated to subsurface as a recharge was 101.2mm. Moreover, groundwater flow runs locally towards the low lands (Bedesa graben) which is considered as discharge area. Yet, regionally it flows from the west to east and southeast directions of the sub-watershed. Finally, Physical parameters measurement, and chemical analysis of water samples were analyzed to study the geochemical evolution of water in the area and the Ca-Mg-HCO3 type is the dominant water type which indicates recharge area ground water with less time of residence and interaction with the surrounding rock/soil. Finally, by comparing with different standards and guidelines, Groundwater in the area is suitable for Domestic, Agricultural and Industrial purposes.Item Stream-Masters of Science in GIS & Remote Sensing Prediction of Flood by Using Artificial Intelligence in the Case of Dire Dawa Watershed, Awash Basin, Ethiopia(Addis Ababa University, 2022-12) Habte Kinfe; Binyam TesfawIn the present century, floods are one of the foremost destroying and costly risks around the world. Its contribution can be ascribed to variables like climate change impacts on the hydrologic cycle, land-use changes and increased density of residence activities in flood-prone areas. However, Flood is a complex event to model and predict for the future. Recently Machine Learning/ Artificial Neural Network (ML/ANN) enhanced the accuracy of weather related event prediction. In Dire Dawa, Ethiopia, flood is forecasted by conventional methods and this method is less accurate and cannot predict the flood hazard effectively. Therefore, this study aims to improve flood prediction accuracy in the area by using Artificial Intelligence(AI) such as; SVM (Support Vector Machines), MLP (Multi-layer perceptron),and KNN (KNeighborsClassifier). In this study, data were downloaded from Copernicus European environmental Reanalysis data Agency (ERA5), preprocessed and trained by using python language. Hourly precipitation and runoff data for 31 years were used for the training of algorithms. Out of these data, 75% were used for training and 25% for testing and validation while doing the machine learning process. The result shows that SVM was found to be the robust performing algorithm with Mean Squared Error of 0.0005046, and R2 of 99.949% compared to MLP (99.947%) and KNN (99.939 %). These methods are useful for the prediction and recommended for the policy makers to consider the AI method for the flood prone areas of the country.Item Volcanic Stratigraphy and Petrography of the Northwestern Ethiopian Flood Volcanics in Upper Kesem River Section Centeral Ethiopia(Addis Ababa University, 2023-06) Misrak Lemma; Gezahegn YirguA petro-stratigraphic study of the volcanic sequence exposed in the Upper Kesem river section is presented. The study area is located in central Ethiopia, North Shewa administrative zone, between Koremash and Shola Gebeya localities, about 80 kilometers north-east of Addis Ababa. The study examined a nearly continuous, ~1080-m thick sequence of stratigraphically preserved basalt flows and intervening silicic pyroclastic deposits. The lower contact of the volcanic sequence is not exposed in this river section. Following a comprehensive field investigation, lithostratigraphic logs for various sections are presented. The sequence is dominated by flood basalts (~78%) with significant proportions of felsic lavas and pyroclastic deposits (~22%) towards the top part of the succession. The very top of the volcanic succession comprises of shield-forming basaltic lava flows and scoraceous deposits. Paleosols and clastic sediments are commonly found as thin layers interbedded within the volcanic sequence, indicating time gaps in eruptive activity. This sequence includes the main phase of flood basalt volcanism and the transition to the termination of flood basalt activity From the constructed composite volcanic stratigraphy , five lithostratigraphic units have been identified, namely 1) Lower Basalt, 2) Lower Rhyolitic Ignimbrite, 3) Upper Basalt, 4) Upper Rhyolitic Ignimbrite, and 5) Shield Basalt. These lithostratigraphic units correlate very well with sequences described in other sections of the Northwestern Ethiopian plateau. A total of 25 representative samples from these stratigraphic units have been studied petrographically. The petrographic studies reveal that only basalts and felsic volcanics have been identified; rocks of intermediate compositions have not been found, indicating a bi-modal petrological distribution for the volcanic sequence. Overall, the basalts exhibit a wide range in their modal mineralogy and phenocryst assemblage. This variation suggests a polybaric plumbing system for the basaltic lavas with several magma chambers developed at various depths within the crust and with each chamber undergoing independent recharge and fractionation processes. Shield volcanism likely represents a decrease in magmatic flux over time. The large-volume silicic pyroclastic deposits further reveal that flood basalt volcanism was accompanied by the development of large and shallow magma chambers, in which basaltic magmas were stored and underwent extensive fractionation and evolution. These deposits further highlight that large and long-lived silicic volcanic complexes with large calderas must have developed on the flood basalts.Item Steady State Numerical Ground Flow Modeling of Ada’a Plain Aquifer Upper Awash Basin(Addis Ababa University, 2022-06) Gashahun Etefa; Dessie NadewThe Ada’a plain is located within the upper awash basin, East of Addis Ababa City, Central Ethiopia. The Steady state Numerical groundwater flow modelling was carried out to understand present groundwater conditions in the Ada’a Plain and to help estimate groundwater availability and water levels in response to present withdrawal and potential future development. In this thesis a WetSpass modeling was used to estimate the groundwater recharge. Results of the study showed that the total groundwater recharge in the study area is 119mm/year (13.45% of the mean annual rainfall).The study area was modelled with a grid of 266 columns x 301 rows with one-layer unconfined aquifer extending up to 450m depth. All the grid size has uniform lateral dimensions of 200m by 200m. Natural recharge due to rainfall and groundwater inflow from specified flux formed the main input to the aquifer system and the output was made of abstraction from pumping wells and base flow to the south eastern direction towards the rift valley. The simulation was carried out using Visual MODFLOW software and calibrated for the 2007 groundwater levels at 69 observation wells. The Water levels in the model are most sensitive to recharge and the horizontal hydraulic conductivity. The computed groundwater level contours have been following the trend of observed ones. The numerical simulation model developed was applied to assess the responses of the Ada’a plain aquifer water level under different pumping scenarios during the next 20 years. Analysis of two different development schemes were formulated to predict the future response of the aquifer under long-term water stress. The computed groundwater budget based on analysis of two different groundwater abstraction scenarios that were formulated to predict the future response of the aquifer under long-term water stress is indicated that the groundwater pumping declined groundwater level and groundwater storage of the plain. Natural recharge due to rainfall and groundwater inflow from specified flux it is an important factor for the sustainability of the groundwater of the plain; however, the intensive abstraction of aquifer decreases the groundwater out flow to the rift valley.Item Geospatial Technology–AI (Machine Learning Algorithm) Application in Flood Inundation Frequency and Extent Analysis and Modeling in Becho Plain, Western Central Ethiopia(Addis Ababa University, 2024-06) Jifara Dabessa; Tibebu KasawmarFloods are one of the most devastating forces in nature. Flooding is a significant natural hazard affecting the Becho plain in western-central Ethiopia, causing extensive environmental, social, and economic damage. This study utilizes advanced geospatial technologies and artificial intelligence (AI) techniques, machine learning (ML) algorithms, to predict and analyze flood inundation frequency and extent in this region. The study integrates historical flood records from the Awash River (1995−2018), climate data (1990−2023), and SAR imagery (2015−2023) to examine the relationship between climatic variables, flood events, and the spatial extent of inundation. The analysis involves evaluating various flood frequency models such as Generalized Extreme Value (GEV), log-Pearson III, and Gumbel distributions, with the GEV distribution demonstrating the best fit for river flow data (K-S statistic of 0.17 and p-value of 0.39). Furthermore, machine learning models including Support Vector Regression (SVR), Random Forest (RF), and Linear Regression (LR) were applied to predict flood frequencies and extents. Linear Regression was identified as the most accurate model, achieving a Mean Absolute Error (MAE) of 17.71 and a Cross-Validated MAE of 20.63. The calculated flood frequency and river flow overall mean and rainy season, the trend analysis showed a general increasing trend in the mean flow, with an overall trend of 0.12 m³/s per year and a rainy season trend of 0.56 m³/s per year. Moreover, based on linear regression analysis of time series flood extent, the slope is positive that the area flooded is increasing per year. Furthermore, geospatial analysis revealed critical flood-prone areas and their temporal changes, providing valuable insights into flood dynamics. The results highlight that integrating geospatial and AI methodologies significantly enhances the prediction and modeling of flood-prone areas. This approach offers a robust framework for improving flood risk management and mitigation strategies, ultimately contributing to better preparedness and resilience in the Becho plain.Item Groundwater Resource Potential Assessment in the Upper Guder Catchment, West Shoa, Central Ethiopia(Addis Ababa University, 2024-09) Getu Tarafa; Behailu BirhanuThe purpose of this research is to assess the upper Guder subbasin's groundwater resource potential using hydrometeorological, hydrogeological, and hydro chemical data analysis. The Guder Catchment, which is the main tributary of the Abay Sub-basin, is located between latitudes 1011758mN and 962477mN and longitudes 321928mE and 405109mE. The watershed spans roughly 2200 km2. Extremely rough terrain, a dendritic drainage pattern, and a tropical to tropically wet and dry climate are its defining characteristics. The area elevations range from 1700 to 3300 m.a.s.l. The catchment's annual precipitation is estimated to be 1267.2 mm/year using the long-term mean monthly rainfall data. The estimated PET values, derived from the Penman and Thornthwaite method, are 995.83 mm/year and 738.77 mm/yr. AETs of 774 mm/year and 733.48 mm/year have been determined using the Turc and soil-water balance approaches, respectively. According to water balance and chloride mass balance methods, the yearly groundwater recharge was estimated to be 148 mm/year and 236.89 mm/year, respectively. The Actual evapotranspiration, surface runoff, and average annual long-term groundwater recharge in the catchment have all been modeled by the wetSpass model. The findings show that the annual results are 558.4 mm/year,340.5mm/year, and 298 mm/year, respectively. The catchment contains the following lithologic units: Jima lower basalts and Tarmaber formation; Tertiary volcanics (Lower Basalts, Guder-Babicha basalts and Upper basalt, Alaji Rhyolite and plugs); Quaternary sediment (Alluvial and Eluvium); and Mesozoic (Abay beds, sandstone). The most extensive lithology in the study area is found in tertiary volcanic rocks. The basin is classified as a local aquifer, extensive and moderately productive porous aquifers, extensive and highly productive fissure aquifer, extensive and highly productive porous/fissured aquifer, low productive fissured/porous aquifer, and aquitards based on qualitative and quantitative analysis of aquifer/aquitard characteristics. The primary water-bearing component of the catchment is the weathered and fractured volcanic rocks. Higher discharge, hydraulic conductivity, and transmissivity values are mapped at or near fractured areas and towards the outlet based on the available borehole data. The regional groundwater flow is typically northward, and water moves from the surrounding highlands to the discharge areas along a low hydraulic gradient. According to the hydro chemical analysis, the predominant cation is Ca, and the predominant anion is HCO3. According to graphical plots, the predominant water types in the region are Ca-HCO3 and Ca-Na/Mg-HCO3, which have low TDS and EC values in highland areas (recharge zone) and relatively high TDS and EC values relative to the recharge area. The majority of water sample results indicate that the area is suitable for irrigation and residential use.Item Evaluation of Recharge and Groundwater flow Dynamics in Beles Basin, Upper Blue Nile Basin, Northwestern Ethiopia(Addis Ababa University, 2023-10) Zerihun Muleta; Tenalem AyenawThe demand for groundwater is growing, leading to the identification of this valuable resource as the focal point for investigation, administration, and preservation. The Beles basin's groundwater resources and groundwater dynamics have been both quantitatively and qualitatively analyzed in this work. Therefore, evaluating groundwater recharge and groundwater flow dynamics utilizing Wetspass,baseflow separation and chloride mass balance approaches was the primary goal of the current research project. The annual recharge of the basin is predicted to be 223.40 mm/year based on the results of the Wetspass model, which corresponds to around 13.86% of the annual rainfall that infiltrates into the aquifer. The model also shows that around 36.35% of the total annual precipitation is accounted for by direct runoff. Furthermore, the Main Beles River at Beles Bridge and the Gilgel Beles river catchments near Mandura town were selected as the primary rivers for assessing the recharge process within the Beles basin. Through baseflow separation, it was determined that the basin experiences an annual recharge of 203.52 mm/year, accounting for 12.63% of the total annual rainfall that replenishes the aquifer. Interestingly, the basin exhibits higher baseflow during the summer months due to increased precipitation and higher evapotranspiration rates. The baseflow index, which indicates the contribution of groundwater to rivers, is highest during the rainy season and lowest during the dry season. Lastly, the chloride mass balance method was employed to estimate groundwater recharge in the area. The findings revealed chloride concentrations of 0.74 mg/L in rainfall and 4.93 mg/L in groundwater. As a result, the CMB method determined that the groundwater recharge in the Beles catchment is approximately 241.9 mm/year, which corresponds to 15% of the annual precipitation that infiltrates into the groundwater reservoir. By examining groundwater level readings from 3 boreholes, 12 shallow wells, 16 hand-dug wells, and information from 89 springs, the groundwater flow dynamics is controlled by surface morphology and structures and flows from the northeast towards the west, aligning with the flow of the Beles River.Item Identification of Degraded Rangeland Areas, and Rehabilitation Site Analysis for Feed Specious Growth: the Case of Borana Rangeland, Oromia Region, Ethiopia(Addis Ababa University, 2023-02) Belachew Tsehay; Biniam TesfawLivestock production is mainly dependent on the productivity and sustainability of the rangelands’ capacity to supply feed for the livestock. However, in recent times the Borana rangeland is unable to sustain supply enough feed to the livestock because of the degradation of the rangeland. Remote Sensing and GIS techniques are of paramount importance to investigate degradation hotspots and select suitable rehabilitation sites for sustainable rangeland. Therefore, this research aims to assess and identify degraded areas as well as suitable sites for rehabilitation in Borana Zone using Remote Sensing and GIS Techniques. The data used in this paper are Landsat 7ETM+ and Landsat 8 OLI Satellite images of 2002, 2012 and 2021, elevation, soil, and climate data. Land Use Land Cover (LULC) degradation, soil degradation due to erosion and deposition, and soil pH degradation were considered as rangeland degradation indicators. LULC, soil (soil depth, soil texture, soil pH, soil OC, and total Nitrogen (TotN)), elevation, rainfall, and temperature factors were used for suitability analysis. Weighted overlay analysis, and Multicriteria decision Analysis (MCDA) method supported by Analytical Hierarchy Process (AHP) were applied to identify the degraded areas and suitable sites for rangeland rehabilitation. The result of the study indicates that 6.33% of the rangeland cover is highly degraded. Whereas, 46.98%, which is the majority of the rangeland, has a moderate degradation level. The marginally degraded area covers 18.97% of the total rangeland while 27.70% of the total rangeland has no or very low degradation. With respect to suitability, the highly suitable site selected covers an area of 7.9%, while the majority of the study area (81.4%) is moderately suitable. The result shows that 10.7% of the area has a marginal contribution for rangeland rehabilitation. Whereas, negligible amount (0.002%) of the rangeland is not suitable. The findings indicate that there is a high risk of conversion of the moderately degraded areas into a highly degraded condition and hence, it is important to Consider degradation protection measures and rangeland restoration sooner.Item Stratigraphy and Petrography of Volcanics from the Western Margin of the Central Main Ethiopian Rift: the Case of Furi Volcano(Addis Ababa University, 2023-09) Eshetu Yohannis; Dereje AyalewFuri Volcano is located near the Western Margin of the Central Main Ethiopian Rift. The location of the area is 26_Km southwest of Addis Ababa. The study's primary goal is to establish volcanic stratigraphy and petrography of Furi Volcano and Escarpment. Various techniques were used to achieve the research objectives, including observation in field, remote sensing, petrographic analysis, and sampling from the study area. Additionally, the study attempts to integrate these data in order to relate them to regional studies investigations on geochronological and magma emplacement behaviour about the Main Ethiopian Rift. The main lithological units exposed in the research area from bottom to top are; partially welded rhyolitic tuff, welded rhyolitic tuff, rhyolite, aphyric basalt, scoria, trachytic basalt, andesite, welded andesitic tuff, welded trachyte tuff, massive to porphyritic trachyte lava. These volcanic rocks are petrographically diverse, with a wide range of mineral compositions and textures; their heterogeneity indicates that magma flux into the lithosphere and depth of fractionation has varied. Total of 25 petrographic samples are studied under the petrographic microscope. The rhyolites and ignimbrite (Welded Rhyolitic Tuff) samples are made of alkali feldspar, quartz, and plagioclase feldspars and are moderately to very porphyritic with up to 10–35% phenocrysts. The felsic units' predominance of alkali feldspar phenocrysts indicates a lower rate of magma flux. The presence of plagioclase, cpx and olivine in basalt reveals the fractionation happened at shallow upper crust, In contrast, the Olv + Cpx mineral assemblages in basaltic lavas demonstrate that crystal fractionation occurred at a deeper crustal level or at the crust-mantle boundary. The upper part of the volcanic unit is dominated by plagioclase and sanidine phenocrysts, intermediate rock, and trachyte lava. The total thickness of volcanic units in the study area is 700m, partially welded rhyolitic tuff to rhyolite (350m), basalt to trachytic Basalt (150m), and andesite to porphyritic trachyte (200m). This indicates that there is a higher abundance of felsic rocks compared to basic rocks. Overall, the study contributes knowledge of the geological history of the western margin of the Central Main Ethiopian Rift with a focus on the Furi Volcano.Item Engineering Geological Evaluation of Embankment Dam Foundation and Construction Materials Characterization of Fato Dam Site, Central Ethiopia(Addis Ababa University, 2023-08) Diribsa Chala; Bayisa RegassaOur country, Ethiopia, has constructed a number of dam projects, including the Renaissance Dam in Abay. The location of the present study (the Fato Dam site) was located in upper Guder, which was a sub-basin of the Abay basin. Geographically located between 360252E/979403N at the right abutment and 360386E/979644N at the left abutment. However, the location of construction materials was here and there within a less than 1km radius around the dam site, except for the sand proposed from the Senkelle area. The local geology of the site was composed of basaltic volcanic formations (vesicular, porphyritic, and aphanitic) from top to bottom. The tops of the abutments were composed of residual soils. Especially in the right abutment, the thickness of the soil reached around 30m from the surface. The objective of the present study was the evaluation of the dam foundation and the characterization of the construction materials used for each zone of embankment. Evaluation of the foundation was mainly in terms of its seepage condition by plaxis software, with construction materials suitability in terms of location, quality, and quantity based on standards and finally recommend remedial measures for the seepage problems. In order to meet the objective of the present study, literature reviews of different papers from both published and unpublished sources and reports of geotechnical investigations (previous work) of the site were used. In addition to these geophysical survey report, bore logging data and other in-situ data done by WWDSE in 2016 and Plaxis 2D software seepage analysis were performed to evaluate the seepage condition of the dam foundation and construction materials at the site. From the borehole data and laboratory test results, the foundation soil was residual, dominantly cohesive soil. The soil of the foundation exhibits low to high plasticity in silty clay and also contains sand. The SPT results of the foundation were interpreted as medium to stiff consistence, while strength fell between 50 and 400 Kpa in the range of 4 to 15 N60 values for dominant in different depths. The permeability of the foundation soil was low to very low. The rock mass rating of the foundation fell from fair to good in its quality. The strength test results of the foundation rock ranged from 42-478 Mpa uniaxial compressive strength, and the permeability packer test result was above the required lugeon (<3LU) values. These were due to the deep, localized fractures and weathering conditions of the site. From the gradation analysis of construction materials, the core material was suitable as it meets the standards. The sand material proposed for the filter and transition zone from the Senkelle area was not suitable because it contained a fine percent above the standards. In turn, locally available basalt is processed and used for filters and transition zones. Rock fills, riprap, and rock toe were also prepared from a basaltic quarry located near the site. The foundation of the embankment dam had seepage problems, so improvement techniques, three rows of curtain grouting of depth 0.75 H (height dam above reservoir), and around the highly affected toe of the dam should be treated with dental treatment of Shasta’s formula