Browsing by Author "Seid, Ali"

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    Evaluation of the Impact of Land Use/Land Cover Changes on Flood Hazard and Risk Prone Areas Using Multicriteria Decision Making Techniques: The Case of Akaki Watershed, Ethiopia
    (Addis Ababa University, 2021-02) Seid, Ali; Berhan, Gessesse (PhD)
    The change in land use/land cover leads to a wide range of environmental impacts and degradation such as flooding, landslide, peak runoff, climate change, and loss of biodiversity around the world. The overall objective of the present study was evaluation of the impact of spatial and temporal variation of land use/land cover change on flood hazard and risk prone area of the Akaki Watershed using multicriteria decision making techniques. To achieve the objective of this study different flood hazard and risk causative factors were used such as elevation, slope, rainfall, drainage density, soil type, surface runoff and topographic wetness index (TWI) were integrated with different land use scenario in Analytical hierarchical process (AHP). Furthermore, the LULC change had been computed using post classification methods and the surface runoff also estimated using the SCS CN method for the three-land use scenario. As the result of the LULC revealed that urbanization was significantly increased. Consequently, the agricultural and forest-land was decreased, whereas the waterbodies were increased from 1988 to 2003 and then decreased from 2003 to 2018. Due to the expansion of built environment and the decline of forestland, the amount of surface runoff increased throughout the study period. in which the runoff increases in the LULC of 2003 from the LULC of 1988 by 17.27mm and the runoff increases in the LULC of 2018 from the LULC of 2003 by 24.85mm. Besides of this the flood hazard, risk and Vulnerability also increased throughout the study period in each land use scenario such as in the land use of 1988 the flood hazard level were estimated to 29.68, 274.53, 961.25 ,513.16, 8.92 km2 in the land use of 1988, 24.83,274.81, 915.62,562.63,9.65 km2 in the land use of 2003 and 17.12, 233.28, 698.21, 827.38, 11.56 km2.Which is subjected to Very low, low, moderate, high and very high respectively. and the flood risk also estimated to 481.68, 532.81 km2 which is subjected to high and very high, 786.83, 39.30 which is subjected to high and very high, and 40.87, 43.87 km2 also subjected to high to very high in the LULC of 1988, 2003 and 2018 respectively. The major findings of the present study revealed that the agricultural land and the built-up area were the most affected by flood hazard land-use class and the downstream of the present study was highly affected by flood hazard and near riverside and high populated areas of the watershed were faced with flood risk. To reduce the effect of flood hazard and risk proper land use management, afforestation, relocation of a house near riverside plays a significant role, specifically for the downstream or the low -lying flood hazard zone.
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    Vegetation Description and Condition Assessment of Protected Rangelands of Alagae and Neteli, in the Main Ethiopian Rift Valley
    (Addis Ababa Universty, 2004-06) Seid, Ali; Bekele, Tamrat
    Rangeland management aimed at animal production can reduce, maintain or even increase range plants diversity. Although the maintenance of biodiversity has become one of the goals in ecosystem management, the relationship between diversity and ecosystem characteristics such as level of herbivory, productivity, and vegetation structure are still poorly understood. The way that management actions constrain (or perhaps magnify) rangeland biodiversity must clearly be understood for sustaining both productivity and biodiversity in rangelands. The purpose of this study was to investigate the floristic diversity and productivity aspects of protected aJId/or managed rangelands in the Main Ethiopian Rift (MER), semi arid agI'o ecological zone. In this paper, the major issues addressed include floristic diversity, vegetation description, herbaceous biomass estimation, and range condition assessment. For the study we used a combination of ecological survey (Zurich Montpelier) method and a standard range condition assessment technique (adopted for the South-Eastern Ethiopian Rangelands). TWINSPAN computer program is used to make vegetation classifications. We examined the relationships between herbaceous biomass production and plant diversity in four native range sites differing in range condition in the Open Grasslands (2), and Wooded Grasslands (2) in semi-arid AEZ of MER. The results of this study have revealed the unique vegetation and rich plant diversity of the two rangelands. Range condition of the four range sites ranged from poor to good and found to be supported by herbaceous biomass production and grazing indicator species. Herbaceous biomass production follows a quadratic relationship with range condition. There is some indication that the humpback model appears to be functional in the MER rangelands. Important information generated has pictured the need for optimizing productivity and biodiversity conservation and elicited information on how agricultural and biodiversity conservation interest should be integrated for the sustainable utilization of rangelands. Key Words: Vegetation Description, TWINSPAN, Range condition, Main Ethiopian Rift Vnlley