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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 formulaItem Mineralogical, Geochemical and Textural Characterization of Akobo Gold Deposit for Ore Beneficiation, South Western Ethiopia(Addis Ababa University, 2023-10) Kisa Workineh; Solomon TadesseGold, a precious metal since ancient times, was one of the first metals used by humans due to its availability in placer deposits. However, efficient gold ore processing faces challenges in achieving optimal gold recovery. Inadequate mineral and geochemical characterizations of the ore contribute to inefficient processing. The objective of the project was to assess the mineralogy and geochemical properties of the Akobo gold deposit in order to identify effective treatment methods for optimal gold recovery. Various methods such as optical microscopy, XRD, ICP-AES/MS and SEM are used to evaluate the mineralogy, geochemistry and texture of the gold deposit. The Akobo gold deposit is hosted in metavolcanics and metasedimentary rock, with common alterations including talc alteration, carbonatization, and silicification. Gold mineralogy identified in the area includes krennerite, montbrayite, buckhornite, austobite, calaverite, nagyagite and gold phosphorus thallium selenide. Gangue minerals associated with gold include magnetite, arsenopyrite, pyrite, chalcopyrite, quartz, actinolite, chlorite, siderite, cubanite, covellite, stibnite, and bertherite. Geochemical analysis showed that gold concentration ranged from 0.001 ppm to 9.76 ppm, silica ranged from 26.2% to 58%, iron oxide concentration ranged from 3.79% to 19.3% and the maximum concentration of titanium oxide is 2.47%. The gold particles in the deposit are encapsulated in gangue minerals and range in size from submicroscopic to microscopic (as it ranges from 20μm to 2mm). Most grain size ranges from 50μm to 100μm (about 41%). The Akobo gold deposit is classified as a refractory ore due to its mineral composition, consisting mainly of telluride along with some sulfide and selenide minerals. The processing of this refractory gold requires pretreatment methods such as roasting, bio-oxidation, and pressure oxidation to minimize losses. Comprehensive metallurgical testing is necessary to select a suitable and efficient gold processing method.Item Paleontology and Biostratigraphy of the Jurassic Carbonate Unit, Lemi -Alem Ketema Section, Central Ethiopia(Addis Ababa University, 2023-05) Zekiyat Shemsu; Balemwal AtnafuA study was conducted on the Jurassic carbonate unit in two sections along the Lemi–Alem ketema road across the Jemma River in the Blue Nile Basin. The unit hasn't been researched in terms of age, facies, depositional environment, and calcareous microfossil studies. Therefore, this study aimed to assess the biostratigraphy, facies, paleontology, and depositional environment of the carbonate unit in the Jemma sections. Detailed morphological descriptions, laboratory preparations, microscopic examinations and comparisons of the reported specimens with varieties of photos, field observations and measurements were used to achieve the objectives. Based on lithofacies analysis the carbonates in the study area were categorized into six types. They are fossiliferous marly limestone, coquina, bioclastic limestone, micritic limestone, marly limestone, and clayey marl. Based on petrographic examination nine microfacies were identified. These are bioclastic mudstone, bioclastic wackstone, non-laminated homogenous mudstone, bioclastic rudstone, pelbiopackstone, coated and rounded bioclastic packstone, bioclastic packstone, sandy limestone and marl-limestone alteration. The paleontological investigation of the studied sections indicated that the carbonates are abundant in macro and micro-fossils which provide information for biostratigraphic and paleoenvironmental interpretations. For biostratigraphic interpretations, index fossils of foraminifera assemblages; Kurnubia palastiniensis (Kp), Anchispirocyclina lusitanica (Al), Kurnubia wellingsi (Kw), Nautiloculina oolithica (No), Alveosepta jaccardi (Aj), Pfenderella arebica(Pa), Siphovalvulina variabilis(Sv), Valvulina lugeoni (Vl), Redmondoides lugeoni (Rl), Conicokurnubia orbitoliniformis (Co) and, Everticyclammina virguliana(Ev)were used. One index fossil from dasyclad green algae, Clypeina jurassica (Cj) was used. According to the index fossils, the Jemma sections of Antalo limestone are dated from Callovian to late Tithonian. Microfacies association indicates a depositional environment of the carbonate unit was deposited in a range of environments, that are open marine, shoal, lagoon, and tidal flat.Item Stability Assessments on the Selected Reservoir Slopes of Ajima Earth Dam North Shoa, Central Ethiopia(Addis Ababa University, 2024-01) Demessie Mulu; Trufat HailemariamThis study was conducted in the Ajima Chacha earthen dam area in North Shoa, central Ethiopia. The study aimed to assess the stability of three critical slopes selected in the dam reservoir. These slopes were selected based on their geometry, steepness of slopes, slope material weathering conditions, rockmass discontinuity, and lithology type, which makes them prone to failure. The failure of these slopes can lead to significant problems in the dam reservoir, which is why assessing their stability is crucial for ensuring the safety of the dam. To conduct the stability analysis, a comprehensive field investigation was undertaken, and rock and soil samples were collected from the selected slopes for testing in the laboratory. The input parameters obtained from these tests were used in the slope analysis carried out using Fast Lagrangian Analysis of Continuum (FLAC2D) and DIP software. However, FLAC2D was mainly used for stability analysis in this research. The Kinematics analysis was conducted on the upper section of RS-1, which is located on a highly fractured and weathered rhyolite unit and toppling failure type is shown from the DIP analysis. The slope analysis of the entire section of RS-1, RS-2, and RS-3 was done using FLAC2D. The FOS (Factor of Safety) for RS-1, RS-2, and RS-3 was 1.63, 1.42, and 1.32, respectively, under static dry conditions. Under static saturated conditions, the FOS for RS-1, RS-2, and RS-3 was 0.99, 1.12, and 1.24, respectively. Since the FOS (Factor of Safety) for slope one (RS-1) under static saturated conditions was less than one which indicating instability and measures should be taken to stabilize the existing slope. Furthermore, evaluating the dam reservoir slopes' stability under seismic conditions would provide a better understanding of dam safety in the long term.Item Stability Analysis of Jointed Rock Mass Foundation of Concrete Gravity Dam and Slope Stability of Abutment(Addis Ababa University, 2023-12) Mamo Methe; Bayisa RegassaFor high-performance operations and the safety of the dam structures, it is essential to study the rock mass foundation of major dams. Numerical modeling can be used to overcome some of the limitations associated with researching rock mechanics, such as the need for extensive laboratory testing for geotechnical engineering of dam foundations. Numerous researches have employed numerical modeling analysis to identify the failure model and resolve foundational issues pertaining to rock mechanics. The aim of this study is to examine and analyze the stability of the jointed rock mass foundation and abutment slope stability of Koysha RCC dam. The foundation of the concrete dam is affected by complex geology, and two sub-vertical joint sets and one sub-horizontal joint set are dipping sub-parallel to the river direction, frequently infilled with thick, soft compressible clay and decomposed rock remnants. The joints are cutting each other. In this research, a distinct element model (DEM) tool, namely 3DEC 5.20, is used to study and analyze the stability of the foundation. This model enables the building of material and joint models as discontinuous mediums. Secondary sources have been the main sources of the required material properties. The Mohr Coloumb elastic, completely plastic model served as a representation of the constitutive block model of the rock and soil components. Perfectly elastic joint model properties served as a representation of the joint qualities. In addition to the discontinuum medium, the equivalent continuum concept was used to reduce calculation times and simplify the study. The results of the central foundation analysis indicated that the jointed rock foundation of the dam was in a state of significant deformation along the infilled J2 joint under all loading conditions. The displacement keeps propagating laterally and vertically following the infill materials along the joint. The result of the abutment analysis revealed displacement of left crest foundation of the dam. From the compressional z-displacement and the pattern of the displacement along the infilled J2 joint set, the research concluded that the infilled material may be responsible for the deformation rather than the joint itself. Generally, the dam body and the whole rock mass foundation of the dam are found to be stable, except for zones of weakly infilled materials along the J2 joint. In order to improve these weak zones along the joint, remedial measures have recommended based on the results of the analysis carried out for improvement by cement grout.Item Productivity, Water Wells Functionality and Hydraulic Structures of Selected Volcanic Aquifers in Ethiopia(Addis Ababa University, 2024-03) Hassen Shube; Seifu KebedeThe volcanic aquifers of Ethiopia play a vital role in providing groundwater used for domestic, industrial and agricultural water supply purposes in both urban and rural areas. However, in such volcanic aquifers, research indicated that declining water levels due to over exploitation decreased natural recharge and climatic variability and failures of water wells within a short life span after construction. Therefore, the objective of this dissertation is to investigate volcanic aquifers’ variation in hydraulic structures, classification and productivity based on a large data set of hydraulic parameters systematically examined for the age (Eocene to Quaternary) and depth (18 - 882m). This work also addresses the use of geospatial technique to estimate large-scale groundwater flow velocity (Vgw) and 222Rn isotope in estimating Vgw, 222Rn recovery, water residence time and testing the applicability of 222Rn technique in post-construction hand pump wells (HPWs) functionality monitoring. The results revealed that there is a good correlation between the ages of the emplacement of rock with hydraulic properties and there is no depth-wise variation in aquifer productivity. The oldest (Eocene) basalts show lower productivity as compared to the youngest (Quaternary) basalts. The insights gained from the analysis show that increasing the depth of drilling does not necessarily increase aquifer yields and can inform the globalscale groundwater flow modelling efforts. The groundwater flow velocity estimation (Vgw) estimated from shallow volcanic aquifers reveals the characteristics of volcanic aquifers productivity and flow dynamics. The values of Vgw estimated by the geospatial and 222Rn methods show similar trends in all study sites where the high values were observed in highly fractured and weathered basaltic aquifers, while the lowest values were in the slightly weathered, less fractured basalt, trachyte and pyroclastic deposits. But, the Vgw estimated by the geospatial technique (0 and 195 m/day) is higher than Vgw obtained from 222Rn isotope (0.37 and 69.1 cm/day) indicating the lower value in the 222Rn technique is due to the effects of aquifer conditions and borehole efficiency effects. The HPWs have been classified into four functionality classes: fully functional (FF), Unreliable (UR), low yield (LY) and unreliable and low yield (UR&LY). FF HPWs show a high 222Rn recovery revealing a quick through flow of groundwater into the wells, healthy functioning of boreholes without screen clogging effects and a high permeability of the aquifer material in the vicinity of the well. Whereas, UR&LY HPWs show the lowest 222Rn recovery revealing a slow flow of water in the well owing to low permeability, declining water level, screen clogging, poor initial design and high water stagnation in the boreholes. The substantial difference in 222Rn recovery between the four categories reveals the applicability of a naturally occurring 222Rn isotope as a promising independent tool to monitor postconstruction changes in the performance of HPWs without the need for dismantling the HPWs for inspection.Item Landslide Hazard Zonation Mapping of Bonga Town Using Statistical Information Value Model Techniques, Southwestern Ethiopia(Addis Ababa University, 2024-03) Tatek Tadesse; Trufat HaileA landslide is the downward and outward movement of slope-forming material consisting of rock, soil, and artificial fill. In the present study, landslide hazard zonation was carried out in Bonga town in southwest Ethiopia, 449 km from Addis Ababa, the capital city of Ethiopia. The main objective of this study was to prepare landslide hazard zonation based on an information value statistical approach. In the case of landslide hazard zonation map carried out by taking into account the nature and distribution of landslides occurring in the Bonga town. Furthermore, the possible relationship between the landslides and the associated causal factors such as slope, aspect, lithology, land use and land cover, drainage density, and relative relief will be considered in this method. The data for above mentioned have been collected and rating value by using information value statistical approaches for each causative parameters to define the elements of the landslide hazard zonation map. The sum combination of all parameters of the weighted layers into a single map and the classification of the scores of this map into landslide hazard zonation and also verifications were based on the field mapped data identifying the existing landslide and overlaid with the prepared landslide hazard zonation map. The result landslide susceptibility index map has been classified into three landslide hazard zonation classes The results of the landslide hazard zonation map of the present study area through information value methods show classified into three hazard classes 3.64 km2 (27%) of the area belongs to the low hazard class, 5.9 km2 (43%) of the area belongs to the moderate hazard class and 4.2 km2 (30%) of the area belongs to the high hazard class. Whereas, the landslide hazard zonation map of the study area verified based on information value methods, out of seven(7) existing landslides inventory and the result indicated that (71%) of the five past landslides were within the moderate zone of the prepared landslide hazard zonation map. (21%) of the two past landslides occur in high-hazard areas, which have a high hazard class. The remaining (8%) past landslides are of low hazard and have a practical possibility of landslide occurrence. Thus, in general, it can be said that about 96% of the past landslides have been validated by the landslide hazard zonation map, which shows a satisfactory agreement on the rationality of the considered parameters and the adopted bivariate statistical value model technique.Item Integrated Geophysical Investigation for Mapping Groundwater Potential Zones of the Mersa-Girana Sub Basin, North Wollo Zone, Ethiopia(Addis Ababa University, 2024-06) Mehari Sisay; Mebatseyon Shawel; Behailu BirhanuThis study was conducted in the Mersa-Girana sub basin in north wollo zone, Ethiopia. It aims to map the groundwater potential zones in the area. VES and magnetic geophysical methods were employed to achieve this objective. As part of the geophysical survey, 293 magnetic data were collected at 100 meter intervals along east-west profiles and 10 VES points were acquired along four east –west profiles with an interval of 500 meter between the VES points. In addition to the primary VES data, ten (10) VES data were collected from secondary sources. The VES data were acquired using a Schlumberger array and a maximum current electrode spacing of 1000 m. The results reveal the main aquifer depth is between 43 and 351 meters in the area. Furthermore, the analysis of Dar- Zarrouk parameters in the research area shows that 35% of the aquifers exhibit high productivity, while 65% of the aquifers demonstrate moderate productivity. The estimated hydraulic conductivity and transmissivity values are high in the central and eastern region of the research area. The results of electrical resistivity and magnetic measurements also demonstrates the region is strongly affected by faulting, which is believed to regulate the groundwater movement in the underlying volcanic series.Item The Pre-Volcanic Sedimentary Unit in the Kella Section, Western Escarpment, Central Main Ethiopian Rift(Addis Ababa University, 2024-06) Kalkidan Asmare; Balemwal AtnafuIn the western flanks of the Central Main Ethiopian Rift (Kella section), the pre-volcanic sedimentary units which are the main focus of this research were investigated. In the present study, a detailed lithostratigraphic section of the area, undertake facies analysis, reconstructing the paleoenvironment, and detailed petrographic characteristics of the pre-volcanic sedimentary units are addressed. Besides; the lithostratigraphic section of the area was correlated with the regional sedimentary work. Detail field investigation and petrographic analysis were used to achieve the objective. Based on field investigation, three sedimentary units were identified. These are sandstone unit, mudstone unit, and carbonate unit. The volcanic unit overlies the sedimentary unit whereas; the basement unit underlies the sandstone unit. 31 rock samples were prepared for thin sections and examined under a petrographic microscope. The petrographic analysis results of 10 sandstone samples show that the sandstone unit is classified into Subarkose, Litharenite, Sublitharenite, and Quartz arenite. Compositionally sandstone unit is mature to supper mature and texturally it ranges from immature to mature. Based on field description and petrographic results, the siliciclastic rocks are classified into 16 lithofacies types and these are classified under 3 lithofacies association groups. The lithofacies associations are Floodplain deposit, meandering river deposit, and Peritidal environment. From the carbonate unit, 20 thin sections were examined under a petrographic microscope. The analysis results reveal that the unit is classified into 12 microfacies types and grouped under 4 microfacies associations. This is sandy mudstone (MF1), carbonate mudstone (MF2), quartz bearings bioclastic packstone (MF3), biosparite Grainstone (MF4), Packstone mudstone (MF5), Oopelbiosparmicrite Packstone (MF6), Daysclad Grainstone (MF7), biomicrite packstone (MF8) bioclastic wackestone (MF9) biomicrite wackestone (MF10) and bioclastic mudstone (MF11), and Radiolarian wackestone (MF12). The microfacies association of the carbonate unit is classified into three groups. Thus are; facies association 1 (MF3, MF10, MF11), facies association 2 (MF6, MF7, MF9), and facies association 3 (MF1, MF2, MF4, MF5, MF8). Generally, the carbonate unit described in the Kella section was deposited in the shallow marine environment. The overall facies stacking pattern of the study area led to the conclusion of continental to shallow marine environment.Item Paleontology of the Jurassic Calcareous Unit at Sheket Section, Mekelle Basin, Northern Ethiopia(Addis Ababa University, 2024-06) Rahwa Gebrehiwet; Balemwal AtnafuThe Mesozoic sediment rock in Ethiopia outcrop in three different area Mekelle basin, Abay Basin and Ogaden basin. In Mekelle basin the Mesozoic carbonate unit studied in different aspects. The detail facies and paleontological of studies have been conducted in sheket section. This study main aim is to detail investigation of micro and macro paleontology of calcareous unit in the Sheket section by investigates field observation and Petrographic analysis. By using that method micro and macro fossil, the age and the paleoenvironmental was able to determine. Based on the field observation by describe the thickness, texture and color different units were recognize: bedded and Micritic Limestone mostly interbedded with Marl, calcareous shale and Fossiliferous limestone, Marl which gray color and found interbedded with mostly with micritic and fossiliferous limestone but also with calcareous shale, fossiliferous limestone have brown color and have macro sized of bivalve fossil and calcareous shale have laminated and Fissility nature mostly found intercalated with marls. In addition to field investigation twenty thin sections were examined by using Petrographic microscope. Based on both Petrographic analysis and field investigation ten Microfacies type have been recognizing: Bioclastic packstones/Floatstone, Foraminifera Bioclastic/ packstone, Oobiosparite/grainstones, Oopelbiomicritic/wackestone, Bioclastic packstone, Crinoid grainstones, Bioclastic Mudstone, Bioclastic wackestone, Bioclast spiculite /packstone and Peloidal-Bioclastic /wackestone. And also four adjacent depositional environments were interrelated based on micro facies analysis, facies association and lithology those are open marine shelf, slope, plate form margin and deep basin. The overall depositional environment is from shallow to deep marine environment. The diagenetic process that affected the Antalo limestone during the studies includes fracture, cementation, dissolution, micritization neomorphism and silicification. There are different types of micro and macro fossil in the study area based on paleontological studies like coral, gastropoda, bivalve, ostracode, Echinodermata, cephalopoda and foraminifera are recognized. The age of carbonate unit of sheket section indicates as: from Bathonian to Callovian due to the presence of index fossils of pfenderella Arabica, Pfenderina neoucomiensis. Due to the presence of Genus praechrysalidina there is possibility this carbonate unit may be extended to Tithonian. The sheket sections of carbonate unit were correlated with intra regional section of mekelle basin.Item GIS-Based Landslide Susceptibility Mapping in Wuchale Area, South Wollo Zone, Northern Ethiopia(Addis Ababa University, 2024-06) Haile Alemu; Trufat HailemariamThis study was conducted in the Wuchale area in the Amhara regional state of the South Wollo Zone, northern Ethiopia. The study aims to evaluate and map landslide susceptibility in the area. A bivariate statistical information value and frequency ratio models were employed to achieve this objective. Six factor layers responsible for landslide occurrences including slope, aspect, elevation, lithology, LULC, and distance to stream were analyzed. With the aid of GPS devices and Google Earth Image interpretations, 31 landslide inventory points were identified. All the data layers were rasterized with a uniform pixel size of 12.5 m in ArcGIS 10.4, which helps to count the amount of entire pixels and landslide pixels uniformly in the area. The frequency ratio and information value models were applied to 70% (22) of the landslide inventory points to determine the relative significance of each factor class. The weights of each factor class were summed to generate a final landslide susceptibility map using a GIS raster calculator. Using natural breaks interval (Jenks), the research region was categorized into five (5) susceptibility classes: very low, low, moderate, high, and very high considering the landslide susceptibility index ranges. The FR model results indicate that 9 km2 (9%) of the area is covered by very high susceptibility, 11 km2 (11%) by high susceptibility, 17 km2 (17%) by moderate susceptibility, 23 km2 (23%) by low susceptibility, and 40 km2 (40) by very low susceptibility. Similarly, the IV model shows 18 km2 (18%) with very high susceptibility, 12 km2 (12%) with high susceptibility, 17 km2 (17%) with moderate susceptibility, 18 km2 (18%) with low susceptibility, and 35 km2 (35) with very low susceptibility. Validation of the susceptibility map was conducted using 30% (9) of landslide inventory points that were not used in the model–building, yielding area under the curve (AUC) values of 0.78 and 0.828 for the frequency ratio model's success and prediction rates, respectively. The information value model achieved success and prediction rates of 0.786 and 0.83, respectively. These validation results demonstrate satisfactory agreement between the landslide susceptibility map and existing landslides.Item 2D/3D Analysis of Magnetotelluric Data in the Central Main Ethiopian Rift (CMER): Implications for Geothermal Resources(Addis Ababa University, 2024-01) Aklilu Abossie; Shimeles Fisseha; Bekele AbebeThe Main Ethiopian Rift (MER) is a seismically and volcanically active portion of the East Africa Rift System (EARS). In the Central Main Ethiopian Rift (CMER), there are several active volcanoes and calderas that are known to be constantly changing, with periods of rising and sinking. Geothermal resources are often associated with these active volcanoes. This dissertation deals with the analysis of the 2D/3D crustal geoelectric models obtained through 2D joint (TE - transverse electric and TM - transverse magnetic modes) inversion of magnetotelluric (MT) data across CMER and a 3D inversion model from one of the hydrothermal occurrences in the CMER, Ashute geothermal field, which is found close to the western escarpment. This is aimed at investigating heat sources, heat flow paths, and geothermal resources to delineate and characterize the geothermal structures and comprehend the tectono-magmatic setting of the crust beneath the study area. Furthermore, the static shift correction data were used to obtain better and more accurate estimates of subsurface resistivities structure and thicknesses by using 1D joint inversion of TEM and MT data in the Ashute area. Based on the 3D inversion resistivity model, the subsurface beneath the Ashute geothermal site can be described by three main geoelectric layers. The top layer, which is relatively thin and highly resistant (> 100 Ωm) and extends down to 400 m depth, consists of unaltered volcanic rocks near the surface. Below this is a conductive layer (< 10 Ωm) with a maximum thickness of 1 Km, likely caused by the presence of clay layers (smectite, illite/chlorite zones) resulting from the alteration of volcanic rocks. In the third and deepest layer resistance of the subsurface gradually increases to an intermediate range (10–46 Ωm). This could be linked to the formation of high-temperature alteration minerals such as chlorite and epidote at depth, indicating the presence of a heat source. Similar to a typical geothermal system, the increase in electrical resistance below the conductive clay layer may suggest the existence of a geothermal reservoir Otherwise, no exceptional low resistivity (high conductivity) anomaly is detected at depth. The phase tensor analysis results across the CMER show a small beta value at low periods (nearly below 10 s), which indicates 1D or 2D structures, while at long periods (> 10 s), the data show 3D structures with a large value of |β| > 30. This asserts that the 2D inversion model can suitably describe the resistivity structures of the shallow crust. The dominant geo-electrical strike is estimated to be N150E using a Z-invariant and phase tensor azimuth. The results of 2D joint inversion of TE and TM modes seemingly identified partial melt within an upper crustal fracture zone (fault) with a resistivity of less than 5 Ωm at a depth of 12–22 km. This partial melt extends beneath the SDFZ with a width of approximately 10 kilometers horizontally. It could be related to the source of heat for the Ashute and Aluto geothermal fields.Item GIS-Based Statistical Analysis for Evaluation of Landslide Susceptibility Mapping: a Case Study in Wacha-Mizan Road Section, Southwestern Ethiopia(Addis Ababa University, 2024-06) Wegderes Tena; Trufat HailemariamThis study was undertaken in the Bench Maji Zone along the Mizan Wacha-Mizan roadway in southwestern Ethiopia, approximately 562 km from the capital, Addis Ababa. This region is notably susceptible to landslides, causing significant risks to road infrastructure, agricultural lands, and residential areas. The primary aim of this research was to develop a landslide susceptibility map using the Information Value Model a bivariate statistical method. This approach evaluates the influence of historical landslides on each factor contributing to slope instability.Key causative factors identified include slope morphometry, aspect, curvature, soil composition, groundwater seepage, land use, and proximity to streams. Data were meticulously gathered through field investigations and corroborated with secondary sources. The integration of these seven causative factors culminated in a comprehensive landslide hazard susceptibility map. Statistical analysis of the information value revealed that certain classes of causative factors such as colluvium deposits, convex slope curvature, groundwater flow traces, slopes ranging from 25-35 degrees, north-facing aspects, Built up Areas, and proximity within 100m of stream exhibited the highest correlation with landslide occurrences. The resultant landslide susceptibility map delineates the study area into various degrees of risk categories: 20.7 km2 (24.92%) of the study area falls in low susceptiblity, 28.7km2 (34.49%) of the area falls in moderate susceptiblity (MS) class and 33.7km2 (40.59%) of the study area falls in high susceptiblity (HS) class. In general, the susceptibility classes derived from this study are consistent with historical landslide data and the causative factors examined. The findings from the Information Value Model provide a reliable basis for informed infrastructure planning, ensuring enhanced safety within the study area.Item Impact of Climate Change on the Groundwater Resources of Southern Omo Basin, Ethiopia(Addis Ababa University, 2024-05) Merga Leta; Behailu BirhanuIn the present day context of Ethiopia, groundwater is the most economically feasible fresh water supply source used for public water supply, irrigation, and industrial purposes. With the growing demand for water supply, and current limited sources to enable community get access to safe and reliable water supply service, it will be wise to assess how the climate change impacts this precious resources in the arid climatic zone of Southern Omo Basin. To see how climate change impacts on the groundwater resources of Southern Omo Basin, two important steps were employed. Statistical Downscaling of Global Circulation Model on to six local meteorological stations (SDSM) and groundwater recharge estimation using the predicted climate variables up to the end of 2050. The predicted climate variables along with the study area Land use, Soil and DEM data served as input into the ARC SWAT model for annual groundwater recharge estimation up to the year 2050. In the climate variables prediction, it is observed that the temperature and precipitation generally increased which in turn gave rise to increased estimation of annual groundwater recharge. From the SWAT model output, locations with better groundwater recharge rate from available precipitation are identified for use in the development of artificial groundwater recharge. This research work is of utmost importance as it sheds light on the future groundwater recharge conditions in an area that is particularly susceptible to the impacts of climate change. One of the limitations of this work arises from the fact that the SWAT model was run using its own system simulated values due to the unavailability of certain climate variables, like relative humidity, wind speed, and sunshine hours at the local meteorological stations. Given its strategic location for border markets, tourism, and high-potential agro-investment opportunities, the study area is highly likely to be transformed into a bustling development corridor. Consequently, it becomes imperative to conduct additional research to comprehend the underlying reasons behind groundwater salinity and its pervasive spread, in order to devise effective mitigation measures.Item Groundwater Potential Study Using Geophysical Methods Around Harbu Town, South Wollo, Ethiopia(Addis Ababa University, 2024-06) Awol Mohammed; Mebatseyon ShawelThis study was conducted in the Harbu area of the Amhara regional state, South Wollo Zone, north central Ethiopia. The present study aims to assess groundwater potential zones and aquifer characterization in the area. Vertical Electrical Sounding (VES) and magnetic methods were employed to achieve this objective. Using a Schlumberger arrangement, thirteen (13) VES points were collected with a PSI resistivity meter. Additionally, 230 magnetic data points were collected using G600 Proton Precession Magnetometer. The magnetic survey was conducted along an east-west orientation with intervals of 100 meters along each traverse. Diurnal and IGRF corrections were applied to isolate the magnetic field arising from subsurface geological units. Subsequently, the upward continuation technique was used to differentiate between shallow and deep-seated geological formations. Various maps were generated using Oasis Montaj software, including a residual anomaly map, a tilt derivative map, and an Euler deconvolution map. A low residual magnetic anomaly was observed toward the southeast and northwest parts of the research area. Euler 3D deconvolution maps indicated variations in the depth of contact within the study area. The 2D magnetic model along the profile revealed variations in sediment thickness. To illustrate vertical and horizontal variations in apparent resistivity across the study area, a sliced stacked map was created. Additionally, geoelectric sections were prepared to provide a quantitative interpretation of apparent resistivity by integrating borehole data and VES curve models. The pseudo-depth sections showed that the central part of the study area corresponds to low apparent resistivity. The geoelectric sections indicated that the central part is characterized by thick alluvial sediment and a deep basement. The relationship between transmissivity (T) and transverse resistance (TR) in the Harbu-Chefa graben was derived as: T = 0.6239TR - 746.18. This equation was used to extrapolate transmissivity and hydraulic conductivity of the study area.