M.SC. Dissertation
Land use and land cover changes have become a major challenge on the sustainability of the Little Ruaha River catchment (LRRC). Agriculture expansion by means of slash and burning farming methods and urbanization are mainly responsible for the significant alteration of the important natural biophysical covers such as forests and wetlands in the LRRC. This alteration in turn has influence on various hydrological and ecological processes which likely to impends the sustainability of the catchment productivity. A study was conducted to evaluate the hydrological impacts of land use and land cover changes on the LRRC using the Soil and Water Assessment Tool (SWAT). “Fix-changing” method under changed land use scenario was used to evaluate the impacts of land use dynamics on the hydrological response of LRRC. Comparison between observed and predicted stream flow confirmed that the initial SWAT model run, requires calibration of stream parameters in order to give a more accurate output from the model. The calibration and validation were performed at three-gauge stations (Makalala, Ihimbu and Mawande) using sequential uncertainty fitting (SUFI-2) in the SWAT Calibration Uncertainty Program. The model performance was assessed based on four objective functions. The statistics showed good results for two gauging stations (Makalala and Mawande) with NSE of 0.62 and 0.65 respectively.
The study has revealed that there have been notable impacts caused by land use/cover changes in water and sediment yield. The average annual surface runoff increased by 3.53 mm, sediment yields increased by 1.2 t/ha, long-term average annual river flow has increased with the annual values of 7.3mm, while base flow decreased by 2.86 mm. The future prediction scenario indicates that by the year 2040, the average surface runoff, annual river flow and sediment yield are expected to be 154.28 mm, 22.6mm, 11.35 t/ha respectively. The study recommends a proper enforcement of laws and regulations relating to natural resource and suitable land use planning and management in order to ensure sustainability of the catchment.
LIFELand Project