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|Title: ||THE EFFECT OF LAND USE CHANGE ON HYDROLOGY OF AKAKI CATCHMENT|
|Authors: ||ABDRHMAN, BERGA|
|Advisors: ||Dr. YONAS MICHAEL|
|Copyright: ||Jul-2011 |
|Date Added: ||16-May-2012 |
|Publisher: ||ADDIS ABABA UNIVERSITY|
|Abstract: ||The main goal of this study is to assess the past and potential future land cover changes, and their impact on the hydrology of the Akaki catchment which is located in upper-Awash basin with a total area of 1429 km2. Specifically, the study analyzed the historical land cover changes (1973 to 2000) that have taken place in the catchment and its effect on the hydrology of the catchment. Also land cover change of future scenario was used to determine the potential effect that will happen on the catchment hydrology.
This study contributes a lot on understanding history of development progresses and their impact on land use and land cover change which influences the streamflow directly. This enhances the ability of planners, researchers and city development actors to formulate and implement sound policies to minimize undesirable future impacts and management alternatives. Also the study has significant role on future flood control of the study area.
The land cover changes within the watershed were examined through classification of satellite images with integrated use of ERDAS imagine (Version 9.1) and Arc GIS software. The Soil and Water Assessment Tool (SWAT) model was used to investigate the impact of land cover change on streamflow of the study area. The model was set up using readily available spatial and temporal data, and calibrated against measured discharge.
Land cover change analysis has shown that the Settlement area has increased from 4.5% to 12.5%, Cultivated land from 35% to 44% between 1973 and 2000, while Forest area has decreased from 19% to 15% and Grass land from 41% to28%.
Sensitivity analysis result shown that both Curve Number (CN) and Alpha factor are the most sensitive parameters affecting the hydrology of the catchment. The model was calibrated from 1997-2002 and validated from 2003-2004 at the Big Akaki river which is gauged part of the catchment. The performance of the model was evaluated on the basis of performance rating criteria, coefficient of determination (R2), Nash and Sutcliff efficiency (NSE), and percent deviation. The R2 and NSE values for the catchment were 0.87and 0.85 for calibration, 0.81 and 0.76 for validation respectively.
The evaluation of the SWAT model response to these LU/LC changes shows annual stream flow was increased by 9% from 1973 to 1986 and 17% from 1986 to that of 2000. Generally, the analysis indicated that flow during the wet and dry season has increased by 16%, decreased by 4%.Finally, from the results above show that the changes in stream flow characteristics could be relayed to the change of the land cover during the studied period.|
|Appears in:||Thesis - Civil Engineering|
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