Preliminary assessment of small hydropower potential using the Soil and Water Assessment Tool model: A case study of Central Equatoria State, South Sudan

Abstract

South Sudan is focusing on the development of large hydropower (LHP) to urgently improve access to electricity in the country. However, LHP investments are expensive and take many years to construct. SHP can be deployed as an alternative to LHP developments as they can be constructed in a shorter time and urgently deliver electricity to locations in need. This study aims to assess run-of-river (ROR) SHP potential in Central Equatoria State (CES) in South Sudan. This is the first study to assess the SHP potential in South Sudan. The main contribution of this research is to produce a dataset showing the geographical locations and generation capacities of the potential SHP sites. The objective of this study is to identify candidate SHP sites in the study area, investigate their suitability for ROR plants and estimate their electricity generation potential. A digital elevation model and a stream network were used to locate sites with a minimum elevation drop of 5 meters, along third and fourth order streams. The Soil and Water Assessment Tool (SWAT) model was used to estimate river discharges in the study area. Model calibration and uncertainty analysis were performed using the Sequential Uncertainty Fitting (SUFI-2) algorithm and daily flow duration curves at 95% dependability were developed from the simulated discharge data. The results showed the availability of eighty-two (82) potential SHP sites along the Bahr el Jebel and the Kaya rivers in CES with a total output power of 1651.69 MW and average annual output energy of 8.68 TWh. Around 60% of the sites had a minimum output power of 10 MW. The highest potential was found in sites between Rejaf and Mongalla, whereas the lowest was along the Kaya river. The study recommended economic analysis and environmental impact assessments before any SHP installation in the area.