Author(s)

Nyemo A. Chilagane^1*, Japhet J. Kashaigili¹, Edmund Mutayoba², Paul Lyimo³, Pantaleo Munishi³, Christine Tam⁴, Neil Burgess⁵

¹Department of Forest Resources Assessment and Management, Sokoine University of Agriculture, Morogoro, Tanzania.
²Department of Water Supply and Irrigation Engineering, Water Institute, Dar es Salaam, Tanzania.
³Department of Ecosystem Sciences and Conservation, Sokoine University of Agriculture, Morogoro, Tanzania.
⁴WWF, Dar es Salaam, Tanzania.
⁵UN Environment World Conservation Monitoring Centre (UNEP-WCMC), Cambridge, UK.

Little Ruaha River catchment (6370 Km²) in the Southern Agricultural Growth Corridor of Tanzania (SAGCOT), is one of the country’s most significant waterways due to its ecological composition and economic value. Regardless of its ecological and economical value, the regional hydrologic condition has been tremendously affected due to land uses alteration, influenced by different socio-economic factors. This study aimed to understand the associated impacts of the present Land Use Land Cover (LULC) change on the surface runoff and sediment yield in the Little Ruaha River Catchment. Hydrological modelling using Soil and Water Assessment Tool (SWAT Model) was done to quantify the impact of land use and land cover dynamics on catchment water balance and sediment loads. The calibration and validation of the SWAT model were performed using sequential uncertainty fitting (SUFI-2). The results showed that, for the given LULC change, the average annual surface runoff increased by 2.78 mm while average annual total sediment loading increased by 3.56 t/ha, the average annual base flow decreased by 2.68 mm, ground water shallow aquifer recharge decreased from 2.97 mm and a slight decrease in average annual ground water deep aquifer recharge by 0.14 mm. The model predicts that in the future, there will be a further increase in both surface runoff and sediment load. Such changes, increased runoff generation and sediment yield with decreased base flow have implications on the sustenance flow regimes particularly the observed reduced dry season river flow of the Little Ruaha River, which in turn cause adverse impacts to the biotic component of the ecosystem, reduced water storage and energy production at Mtera Hydroelectrical dam also increasing the chances of flooding at some times of the year. The study recommends land use planning at the village level, and conservation agricultural practices to ameliorate the current situation. Developing multidisciplinary approaches for integrated catchment management is the key to the sustainability of Little Ruaha River catchment.

Land Cover, Land Use, Sediment Loading, Surface Runoff, SWAT Model

Chilagane, N. , Kashaigili, J. , Mutayoba, E. , Lyimo, P. , Munishi, P. , Tam, C. and Burgess, N. (2021) Impact of Land Use and Land Cover Changes on Surface Runoff and Sediment Yield in the Little Ruaha River Catchment. Open Journal of Modern Hydrology, 11, 54-74. doi: 10.4236/ojmh.2021.113004.