Hydrological Studies for the Assessment of Run-of-River Hydropower Potential and Generation over the Wouri-Nkam River using GIS and Remote Sensing Techniques

Abstract

Cameroon has several renewable energy sources, including solar, wind, and hydropower. With the liberalisation of the hydroelectric energy sector in Cameroon, rural communities are yet to feel the impact. Small Hydropower projects should have been developed to curb the acute shortage of electricity within these localities and beyond. This is not the case yet. It is in this respect that this study is carried out: to assess the hydropower potential of the Nkam Division and environs and propose sites for the development of hydroelectricity. Geographical Information System, Remote Sensing techniques, and hydrological models (HEC-HMS) were used. Grid analyses were carried out on the Digital Elevation Models (DEMs) using the Watershed Modelling System software to delineate the catchment basin with the sub-basins. Digital Soil and Land use data were obtained from the Harmonised World Soil Data and World Land use Data respectively, which together were used to calculate the Composite Curve Number in QGIS for the various sub-basins. The curve numbers together with other hydrological parameters were used to develop a HEC-HMS deterministic hydrologic model for the catchment basin. The resulting model was calibrated and validated in HEC-HMS, using precipitation data obtained from the localised Yabassi weather station and discharge values from a gauging station at Yabassi. The calibrated peak discharge produced an absolute error of 3.4% and a Nash-Sutcliffe value of 0.301. The hypsometric curve presents a hilly landscape, with 40% of the surface area having elevations of between 10 to 30 m, favouring the development of small scale hydro systems. The RETScreen software was used for the hydro-energy analyses and the estimated potential power, for a hydraulic head of 20 m, stood at 13,813 kW. The values of the Benefit-Cost Ratio value of 1.3 and the Net Present Value greater than zero show that the project is very practical and profitable. It follows that Small and Medium Run-of-River Hydropower Plants can be developed from the Wouri–Nkam Reach, the significant reach in the river network of the Catchment Basin, with an estimated compensation flow of 133.17m3/s for ecological continuity. The project will reduce about 27,064.8 tons of CO2 from the atmosphere.