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| dc.contributor.author | NURYE, SEID | |
| dc.date.accessioned | 2020-03-16T08:02:53Z | |
| dc.date.available | 2020-03-16T08:02:53Z | |
| dc.date.issued | 2020-03-15 | |
| dc.identifier.uri | http://hdl.handle.net/123456789/10317 | |
| dc.description.abstract | Morphological change of natural rivers interms of vertical adjustment and horizontal planform is an important indicators of true channel stablity and have significant effect on lateral bank retreat. Hence,this study assess morphological change and the related bank erosion along the Borkena River, Awash Basin, Ethiopia. The study quantifys the different morphological metrics extracted from satelite images to understand the river panform and HEC-RAS 5.05 Model with its extension of BSTEM was used to assess the vertical adjustment, bank erosion and stablity. River cross section data collected by total stations, bed and bank material type and gradations, dischrge at gaging stations and sediment datas were used to calibrate and validate the Model. From the Satelite images of the year 2008, 2013 and 2018, the river center lines, banks and width of the river were digitized and sinuosity, braidedness index, width to depth ratio and longitudinal slope were calculated to assess the planform chnges. The result showed that, the change in Sinuosity value is insignificant for the year 2008 (1.159) and 2013 (1.156) but the sinousity value found for the year 2018 is high (1.660). Also, the Braidedness index value estimated as 1.385 (2008), 1.457 (2013) and 1.878 (2018). Longitudinal slopes of the study reach shows insignificant variations from 0.011 to 0.012 and the width to depth ratio is above 40m/m. the river bed is dominated by gravels (D50 >4.75mm) and the studied reach grouped under D-stream type. The studied reach of Borkena River are characterized by both aggrading and deggrading natures alternatingly with an average aggrading and deggrading value of 0.047 m/y and 0.048m/y respectively.The bank retreated on average 0.0519 m/y, 0.0010 m/y and 0.06 m/y for the upper, lower and tributary banks respectively. Similarly, the result shows stablity for the borkena river banks and instablity for the tributary banks. Generally, this study showed that morphology of the river is unstable horizontaly (planform) and vertically. Hence, appropraite river engineering works should be implemeted in order to minimize the river instability including the banks. | en_US |
| dc.language.iso | en | en_US |
| dc.subject | Hydraulic engineering | en_US |
| dc.title | CHANNEL MORPHOLOGICAL CHANGE ASSESSMENT AND SUSCEPTIBILITY OF BANK EROSION IN THE LOWER BORKENA RIVER, AWASH BASIN, ETHIOPIA | en_US |
| dc.type | Thesis | en_US |
