The Impact of Land Use/ Land Cover Change on Catchment Hydrology and Water Quality of Legedad‐Dire Catchments, Ethiopia

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Addis Ababa


The main objective of this study was to assess the impact of the environmental changes on the hydrology and water quality of the Lege Dadi-Dire catchments. More specifically, the study analysed the land cover change scenarios that were assumed would have taken place in the catchments, and the effect these changes have had on the hydrology and water quality of the catchment. The Soil and Water Assessment Tool (SWAT) model was used to investigate the impact of land cover change on streamflow, sediment, nitrate, phosphorous, and other considered water quality variables yield of the study area. The model was set up using readily available spatial and temporal data, and calibrated against measured values. There was good agreement between monthly estimated and simulated variables for the calibration and validation periods. The simulation of sediment was slightly underestimated but overall, the agreement between the estimated and simulated variables was acceptable. Two approaches have been taken to conduct the study. First, historical land use/cover data of 1960, 1980, and 2008 were taken and the impact of land use/cover change over the period was analysed. Second, the 1990 land use/cover data was used as a base data and scenarios of the future land use/cover were developed. Taking both cases, impacts of land use/cover and their scale were identified in this study. Accordingly, there has been close correlation between land use/cover, stream flow and turbidity. There has been a considerable increase in runoff of about 8.3% in Lege Dadi catchment which is attributing to land use/cover effect. Without climate change, land cover changes considered in the scenarios account for an increase in runoff of about 3.4-49.9% and 14.9-15.3% for Lege Dadi and Dire catchments respectively. Similarly, the sediment yields have also increased more closely with agricultural land use intensification. In relation to the increase in agricultural land, nitrate, phosphorous and other considered variables have shown considerable increase through the application of agricultural inputs such as fertilizers. This will further escalate the problem of water quality and treatment cost of Lege Dadi water treatment plant. Remedial measures have also been recommended



Streamflow, Sediment, Phosphorous