Biosystems Engineering

Permanent URI for this collectionhttps://etd.hu.edu.et/handle/123456789/673

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Start date: 2020End date: 2023

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    IMPACT OF LAND USE/LAND COVER AND CLIMATE CHANGE ON SOIL EROSION IN SILE WATERSHED, LAKE ABAYA-CHAMO SUB BASIN, SOUTHERN ETHIOPIA
    (Hawassa University, 2022-10-25) BIRHANU WOLDE GINDI
    The combined impacts of land use and climate change are significantly affecting natural resources, particularly soil and water ecosystems. Thus, studying the impacts of land use/land cover (LULC) and climate changes on soil erosion in the Sile River watershed is very essential for proper natural resource management. In this study, the historical change of LULC (from 1987-2020), prediction of 2050, the impact of changing LULC & climate on soil erosion for the years of 1987, 2003, 2020, and future 2050 under two climate scenarios (RCP4.5 & RCP8.5) were evaluated. The Landsat TM for 1987, ETM+ for 2003, and Landsat-8 OLI/TIRS for 2020 were used for LULC classification. Supervised image classification method with maximum likelihood classification (MLC) was applied in the ERDAS Imagine software. Classified historical LULC map serves as a baseline to predict 2050 LULC with considering different driver variables using Multi-Layer Perceptron Neural Network and Cellular Automata-Markov Chain Model integrated with TerrSet software. Daily rainfall data from 1987-2020,102 composited soil samples, ASTER DEM with a resolution of 30*30-meter and classified LULC map was used for erosivity (R-factor) estimation, soil erodiblity (K-factor) analysis, topography (LS-factor) computation, and for both practice (P-factor) and cover (C-factor) determination respectively. In addition, the ensemble means of four regional climate models (RCMs) rainfall data under two scenarios (RCP4.5 & RCP8.5) and predicted 2050 LULC map was used to generate R-factor and both P&C factors respectively for the estimation of 2050 soil loss. A revised universal soil loss equation model (RUSLE) has been used to compute the above factors in Arc GIS software to estimate the rate of soil loss. This study revealed that, in both periods from the year 1987- 2003 and 2003-2020, cultivation land, bare land, and banana land cover were expanded at the expense of shrubland, forest land, grazing land, and water body decline. Sile River watershed experienced substantial LULC alteration and will also be prolonged for the coming several years. The mean annual soil loss for the years 1987, 2003, and 2020 were 13.05, 21.04, and 41.41 t-ha−1 year−1 respectively. The lowest mean annual soil loss was observed in banana land cover and gently slope classes. While highest and severe was detected on bare land & steep slope classes correspondingly. The average soil loss under the RCP4.5 and RCP8.5 scenarios with a future 2050 LULC were predicted to be 56.48 t ha−1 year−1 and 57.11 t-ha−1 year−1 then it will be expected to increase 36.40 % and 38.19 % respectively. LULC, climate change/variability, and the steepness of slope had been believed to be the leading factors that exacerbated soil erosion in the study area. From the finding of this study, prioritized sub-watersheds are recommended for land management intervention, and disseminating banana plantations in the other part of the watershed was suggested. Additionally, climate change will aggravate the current soil erosion problem and would need ecological sound conservation policies and strategies to mitigate the adverse impacts of climate change on soil erosion.
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    TECHNICAL EVALUATION, IMPACTS OF PHYSICAL SOIL AND WATER CONSERVATION STRUCTURES AND SLOPE GRADIENTS ON SELECTED SOIL PROPERTIES THE CASE OF HAWASSA ZURIA WOREDA, SOUTHERN ETHIOPIA
    (Hawassa University, 2023-10-26) BANDIRA BELACHEW DOGISO
    This study was aimed on technical evaluation, impacts of physical soil and water conservation structures and slope gradients on selected soil properties. For the purpose of the study Hawassa Zuria Woreda was selected and Kejima Unibulo, Ounbulo Wacho and Shamena Gerimama kebeles were selected purposively from woreda. Total of 60 structures; 20 soil bunds, 20 fanya juus and 20 micro basins were randomly selected and their dimensions were evaluated according to the standard recommended. 18 soil samples (two treatments ∗ three slope classes ∗ three replications) were collected at a depth of 0-20 cm from kejima unibulo. 364 households were interviewed. Data were analyzed using paired samples T-test, one way analysis of variance and descriptive statistics. In the study area soil bunds, stone bunds, fanya juus and micro basins were implemented. Technical evaluation showed that only vertical interval of soil bund was constructed according to the standard. The result revealed that physical soil and water conservation structures had no impacts on soil texture and had significant impacts on bulk density. Slope gradients had significant impacts on sand soil and silt soil. physical soil and water conservation structures and slope gradients had significant impacts on chemical properties of soil. Farmers were preferred to practice soil bund, fanya juu and micro basin, respectively. Farmers were perceived the benefits of physical soil and water conservation structures as soil fertility improvement, increase crop productivity and restoration of degraded lands. The problems in implementation of physical soil and water conservation structures in the study area were small land size, labor cost, lack of technical skills, inaccessibility of construction materials, lack of interest for young generation to participate in agricultural activities, lack of field guide line for soil and water conservation practices, weak interaction among stakeholders, food insecurity and lack of awareness, respectively. Generally, physical soil and water conservation structures implemented had poor technical quality. There should be awareness creation and trainings for the farmers and development agents. There should be integration of physical conservation measures with agronomic and biological conservation measures and implementation of slope reducing structures along steep slopes in order achieve objectives of erosion reduction.
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    ASSESSMENT OF LAND MANAGEMENT PRACTICES AND ITS CONTRIBUTION TO LIVELIHOODS AT HOUSEHOLD LEVEL: ACASE OF EDO SUB- WATERSHED WONDO GENET WORED SIDAMA ZONE SNNPR, ETHIOPIA
    (Hawassa University, 2020-10-28) WONDIMAGEGN LELISO TULO
    In Ethiopia land is a source of income and means of production on which the livelihood of 85 percent of the population depends. The study was undertaken in Edo sub-watershed Wondo Genet Woreda Sidama Region Ethiopia. The main objective of this study is to assess land management practices and its contributions to livelihoods at household level in the study area. For this study data were collected from 185households respondents from study area. The basic data used for this study were collected from sample households, focus group participants and key informants interview and field observation through structured questionnaire and semi-structured checklists. Descriptive statistics and binary logistic model were employed to investigate association between demographic, socio-economic and institution land management practices. The practiced land management in the study area include: manure application, traditional ditches, stone check dam, soil bund, sand bag check dam, tree planting, crop rotation, intercropping and mixed cropping for land management. Land management practices played a crucial role in arresting runoff, to improved wetlands to down stream and help to reduce erosion hazard. Land management practices had contribution to Environmental performance indicators like soil fertility, soil erosion and vegetation cover but not significant effect. Farmer application of land management practice could possibly be influenced by different factors. Among these factors most have significant association on the practice of management. Whereas other factors were no significant association on the land management practices. This includes age (P=0.034), sex (P=0.005*), marital status (P=0.000*), extension service (P= 0.002*), livestock (P=0.000*) and, educational status (P=0.040*) of household were significant factors in land management practices. However, family size (P=0.076**), farmer experience (0.849**), farm size (P=0.258**), farmer level of perception (P=0.675**) and income of household (P=0.222**) no significant factor on practicing land management in general. As a result, it is recommended that the woreda’s soil and water conservation experts should create awareness to the local people about land management and its contribution
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    APPLICATION OF THE MODIFIED UNIVERSAL SOIL LOSS EQUATION (MUSLE) IN THE PREDICTION OF SEDIMENT YIELD IN AGEWMARIAM EXPERIMENTAL WATERSHED; TEKEZE RIVER BASIN, NORTHERN ETHIOPIA
    (Hawassa University, 2022-10-20) YONAS REDA SHAREW
    The severe effect of soil and water resource degradation in Ethiopia is putting pressure to take soil and water erosion control measures. To support the planning, management, and appropriate use of the soil and water resources the Modified Universal Soil Loss Equation (MUSLE) was used to model eventual sediment loss in Agewmariam experimental watershed. The model uses different methods for the estimation of the runoff energy, soil erodibility, slope length & steepness, cover management, and support practice factors input parameter values; so that calibration, evaluation, and validation of parameter values become mandatory. The model input parameters were collected from a combined process of field observation, laboratory analysis, Google Earth Pro, and GIS processing while cover management and support practice are adopted from literature. Analysis of input parameters was done with the help of ArcGIS and MS-EXCEL. The input parameter maps were overlaid to assign a value and the combined effect of the parameters for the suspended sediment yield was calculated on a raster calculator. The runoff energy factor is the most sensitive parameter followed by the slope length and steepness factor. For the calibration period, the event-based mean observed and estimated suspended sediment yields were 0.2 and 0.23 ton/ha respectively with a little overestimation; while for the validation period, is 0.7 and 0.53 ton/ha with great underestimation. The model evaluation shows a 0.85 coefficient of determination, a 0.85 coefficient of efficiency, and an index of agreement value of 0.96 for the calibration period which can be considered a good model performance, whereas a 0.84 coefficient of determination, 0.65 coefficient of efficiency, and an index of agreement value of 0.83 for the validation period. The result revealed the use of the MUSLE model in its original form without calibration is not proper. The evaluation result shows the model with the appropriate calibration is a good estimator of sediment yield so that it can be used for spatial prioritization of soil and water conservation need within the watershed or extrapolated to the neighboring similar watersheds