Channel Stability Analysis-The Case of Lower Logia River
No Thumbnail Available
Date
2015
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
Rivers dynamically respond to changes in the discharge and sediment supply from the catchments. A change of land use and other natural factors in catchments result in changes on sediment supply and discharge. This process of change of River geomorphology seeking for its equilibrium may affect people and property especially in sensitive areas located adjacent to Rivers. Tendaho sugar factory project is found in Afar regional state near Logia River. Logia River is the cause of destruction of structure of the project and private farm due to over flooding of the bank in the vicinity of the main canal of the project. The river also damage properties adjacent to Logia town. To prevent the loss of lands and properties resulting from the changes in the characteristics of this River reach, stabilization measure should be taken. So this thesis deals with analysis of the stability of the channel reach by evaluating their capacity and stability in response to discharge and sediment supplied from the catchments.
For proper design and implementation of any stabilization measures, analysis on stability and channel capacity of this channel reach should be evaluated. According to the study, flow simulated result the 2.5 return period discharge is almost accommodated within the channel section of the whole station. But there are observed in some adjoining areas flooded by the 50 years and 100years return period discharge. From steady flow analysis of lower Logia River a shear induced due to the flow of the design discharge of 50 years and 100years together with the channel forming discharge which is taken as a 2.5years return period is analyzed and compared from the critical shear stress which result show less thus the bank of lower Logia River can generally get easily eroded and have less resistance to shear. According to sediment analysis the model result which is analysis using the sediment function laursen (Copland) and Yang sediment transport formula, deposition is observed in all River station almost 85% of River station. The remaining River station degradation is observed in station at just downstream of the bridge and upstream of the syphon according to the model results. So it is recommended that the stabilization measure should be implemented with engineering, economical and hydraulic analysis for effective and sustainable stabilization of the Rivers.
Description
Keywords
Lower Logia River, Stability Analysis, Channel Stability