Assessing the Impact of Landuse Change on Streamflow of Ajali River Watershed Using the SWAT Model

Abstract

The increase in human population has led to high demand for food and shelter. These have severely affected our natural ecology with great impact on the hydrology of local watersheds. SWAT model was used to predict the impacts of land use/cover changes of Ajali River watersheds, Aguobu-Umumba, Ezeagu, Enugu State, Nigeria. The objective was to calibrate the SWAT model and apply it to assess the effect of landuses from 1985 to 2015 on stream hydrograph. The required input data were obtained, processes using ArcGIS and used to perform model simulation. The model performed successfully for the study area with R2 = 0.67. Landuse maps for 1985, 1995, 2005 and 2015 were used to perform model runs while keeping other inputs constant. The results showed that there was a general increase in stream discharge from 1985 to 2015 within the period investigated due to forest land conversion to agricultural land. Results show an increase in peak stream discharge by an average of 40m3/s for the month of October within the time period investigated. This study showed the utility of the SWAT model for stream discharge prediction and a scientific tool for watershed management