Assessing the Effect of Land Use Change on the Hydraulic Regime of Lake Awassa
Abstract
For the past years increases in population pressure, government policy and external influences have caused a consistent change in the land cover of the Lake Awassa catchment. The change has come about mainly due to deforestation as is the case in many other areas of Ethiopia. The effects of land cover changes have had an impact on the water balance of the catchment by changing the magnitude and pattern of runoff, peak flow and ground water levels. This study is mainly focused on the assessment of the hydrological response of the catchment in relation to the land cover data of 1965 and 1998 using a Geographic information system (GIS) integrated with the hydrologic modeling. The result of the remote sensing assessment on the land cover of the catchment indicated that natural vegetation decreased by 11,768 ha or 9.06 % between years 1995-1998. This was mainly due to the expansion of agriculture and urban area. Plantation expansion was 20,661 ha or 13.56 % and also urbanization increased by 1,310 ha or 0.89 %. Based on these results, the inflow records were analysed statistically to evaluate if changes in the land cover affected the hydrological response of the catchment. The results of the analysis indicate that the average inflow to Lake Awassa in 1998 was 3.15 m3/sec or 99.34MCM, whereas in scenario year 2017 the average inflow will be 3.5m3/s or 110.38MCM. So because of the land cover change the flow will increase by 0.35 m3/s, that is, 11.04MCM.
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