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- ItemGIS-Based Approach for Morphometric Characteristics and Development of Hydrographs for the Upper Watershed of Jebba Reservoir, Nigeria(Dr Birhanu Assaye, 2021-10-20) Adeogun, A.G., Mohammed, A.A., Ganiyu, H.O. and Salami, A.W.Nigeria's Jebba sub-basins are synonymous to frequent flooding, high rate of erosion, depletion of soil nutrients and unsustainable water use. The uncontrolled flooding may be a result of numerous factors related to topography, geology, climate and human activity. The present work was an attempt to describe the application of Geographical Information System (GIS) and Digital Elevation Model (DEM) for the estimation of morphometric characteristics of eight sub-basins in the upstream watershed of Jebba reservoir, Nigeria. Morphometric characteristics such as topographic, areal, relief and network were determined. Soil Conservation Service (SCS) technique was applied to estimate hydrographs. The study revealed that sub-basin number 3 had the lowest time of concentration and maximum depth of runoff while sub-basin number 2 had maximum ratio of circulation of 1.8 and it is tagged as the area that is highly prone to flood. The peak runoff in the sub-basins ranged between 330.10 and 924.86 m3/s (25-year return period) and for 100-year intervals ranged between 502.69 to 1408.40 m3/s. The estimated peak runoffs can be adopted for designing and constructing erosion control structures in the catchment area.
- ItemDevelopment of Inundation Map for Hypothetical Asa Dam Break Using HEC-RAS and Arc GIS(Faculty of Engineering, University of Nigeria, Nsukka, Nigeria, 2017-12-20) Balogun, O.S. and Ganiyu, H.O.Asa Dam in Ilorin, Nigeria was constructed in the1980s. The dam made of earth material has a length of 507 meters and height of 27 meters. The maximum capacity of the impoundment during the raining season is approximately 43 x 106 m3. Years after construction, tremendous physical development is taking place along the river channel starting from the dam axis towards downstream for a distance of approximately 12 km. It is estimated that several thousands of people are currently living and performing various activities within the vicinity of the river channel. It is therefore necessary to evaluate the risk involved in case of a possible dam break disaster. In view of this, a hypothetical dam break scenario was studied and analyzed using Hydrologic Engineering Center’s River Analysis System computer model. Unsteady flow simulation was performed using geometric data obtained from Digital Terrain Model with 100-year, 24 hr flow event. The HEC-RAS was used in concert with HEC-GeoRAS to assess the flood hazard along the approximately 12 km river channel. The simulated water surface elevations were exported to Arc GIS to produce an inundation map that graphically indicates the extent of the flood hazard. The results show that some important locations such as industrial, residential, motor parks, recreational and places of worship along the river length are prone to significant flood impact. This map serves as an input for emergency preparation programme in the event of the dam break.
- ItemEffectiveness of GIS Based Hydrological Modeling Tool for Sustainable Sediment and Water Management in Asa River Catchment, Nigeria(Michael Okpara University of Agriculture, Umudike, Nigeria, 2018-12-20) Adeogun, A.G. and Ganiyu, H.O.In this study, Soil and Water Assessment Tool (SWAT) was interfaced with Mapwindow-GIS to simulate the hydrology, predict sediment yield, water yield and water balance into sub-basins of Asa river catchment in Kwara State, Nigeria. SWAT was calibrated and validated using measured flow data from January, 2008 to December, 2014. The model was evaluated using Coefficient of Determination, R2 and Nasch-Sutcliffe Efficiency, NSE which give acceptable results of 0.76 and 0.85 for Calibration and 0.70 and 0.74 for validation stage. Highest Annual Sediment yield of 20.71t/ha was recorded in sub-basin 13 while the lowest value of 8.9t/ha was recorded in sub-base 16. Annual sediment production rate was estimated as 437.6t/ha/yr while the total sediment yield of 4,376.t/ha was produced in the watershed during the simulation period. Predicted values of sediment concentration is highest in sub-basin 23 (153,045.9mg/l) and has a lowest value of 26,781.9 mg/l in sub-basin 1. Categorization of erosion prone areas showed that 12 sub-basins are in low erosion prone zone, two (2) sub-basins moderate zone, 14 in severe while 3 sub-basins are in extreme category. The outcome of this study confirmed that SWAT can be adopted as a decision support tool for sustainable sediment and water management in the basin and other watershed in Sub Saharan Africa Countries.
- ItemEvaluation of Hydrokinetic Energy Potentials of Selected Rivers in Kwara State, Nigeria(Korean Society of Environmental Engineers, 2020-04-11) Adeogun, A.G., Ganiyu, H.O., Ladokun, L.L. and Ibitoye, B.A.Hydrokinetic energy system is the process of extracting energy from rivers, canals and others sources to generate small scale electrical energy for decentralized usage. This study investigates the application of soil and water assessment tool (SWAT) in geographical information system (GIS) environment to evaluate the theoretical hydrokinetic energy potentials of selected rivers (Asa, Awun and Oyun) all in Asa watershed, Kwara State, Nigeria. SWAT was interfaced with an open source GIS to predict the flow and other hydrological parameters of the subbasins. The model was calibrated and validated using observed stream flow data. Calibrated flow results were used in conjunction with other parameters to compute the theoretical hydrokinetic energy potentials of the rivers. Results showed a good correlation between the observed flow and the simulated flow, indicated by Nash-Sutcliffe Efficiency (NSE) and R2 of 0.76 and 0.85 respectively for calibration period, and NSE and R2 of 0.70 and 0.74 respectively for the validation period. Also, it was observed that highest potential of 154.82 MW was obtained along River Awun while the lowest potential of 41.63 MW was obtained along River Asa. The energy potentials obtained could be harnessed and deployed to the communities around the watershed for their energy needs.
- ItemEffectiveness of Selected Low Impact Development (LIDS) for Sustainable Stormwater Management in Fast-Urbanizing Residential Areas(2024-06-24) Adeogun, A.G., Sanni, A., and Ganiyu H.OThe global trend of urbanization has led to the widespread conversion of natural land cover to impermeable surfaces. This, in turn, is hindering water infiltration and exacerbating runoff from precipitation. This phenomenon has detrimental effects on the natural environment and water quality. To address these issues of stormwater generation, this study employed the Storm Water Management Model (SWMM) in conjunction with MapWindow Geographical Information System (GIS) v4.X, a hydrologic data software for data, visualization, editing, and integration with other modeling tools to simulate the impact of various Low Impact Developments (LIDs) on mitigating stormwater in the study area. The study area was divided into six sub-basins within the GIS environment and imported into SWMM to assess the effects of selected LIDs, including green roofs, rain gardens, vegetative swales, and permeable pavements. The SWAT model was used to predict water flow in the Malete watershed and surface runoff. The study identified areas susceptible to erosion and categorized them as low, moderate, severe, and extreme. The results showed that permeable pavements exhibited the highest reduction rate, reducing stormwater by approximately 50% across all sub-basins, while green roofs showed the lowest reduction rate of only 0.003%. Regional calibration was implemented, revealing a significant correlation of 71% between simulated and observed flows in the study area. The findings of this study can serve as a valuable decision-support tool for stakeholders and authorities when selecting appropriate LID practices to mitigate the urban impact of stormwater generation.