Impacts Of Land Use And Land Cover Changes On The Ecosystem Services Of The Little Ruaha River Catchment, Tanzania

ABSTRACT

A study was carried out to evaluate spatial and temporal changes that have occurred over a period of 25 years in land use and land cover and their impacts on ecosystem services with strong focus in water and sediments yield in the Little Ruaha River Catchment (LRRC), in Rufiji River Basin. The objectives of the study were to analyze the spatial and temporal changes of land use/cover, assess the impacts of land use/cover changes on water and sediment yields and predict the future change in land use/cover and how it is likely to affect water and sediment yields in the LRRC. In this study, field survey, remote sensing and GIS techniques were employed to assess spatiotemporal dynamic of land use/cover. CA-Markov model was used to simulate the expected changes in land use/cover in the future. SWAT model was employed to simulate the potential impacts of land use and land cover changes in water and sediment yield in the catchment. Results have revealed that there has been a significant land use and vegetation cover transformation from one class to another for the period between 1990 and 2015. Natural forest, riverine forest, water, wetland and woodland decreased by 3.76%, 0.75%, 0.17%, 2.12%, and 8.03% respectively, while plantation, grassland, bushland, cultivated land and built up area increased by 0.57%, 4.71%, 6.02%, 5.76% and 0.73% respectively between 1990 and 2015. Moreover, 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.