Author(s)

Rodrigue Fotie Lele^1,2*, Mihaela Amalia Diminescu³, Issoufou Ouedraogo^1,4, Annette Madelene Dăncila³, Souleymane Pelede¹, Alphonse Emadak⁵, Martin Lompo¹

¹Department of Geology, University Joseph Ki Zerbo, Ouagadougou, Burkina Faso.
²Department of Water and Energy, Green Heart International, Bafoussam, Cameroon.
³Department of Hydraulic Machineries and Environmental Engineering, National University of Science and Technology Politehnica Bucharest, Bucharest, Romania.
⁴Department of Mining Engineering, University Yembila-Abdoulaye-Toguyeni, Fada N’Gourma, Burkina Faso.
⁵Department of Inorganic Chemistry, University of Yaoundé I, Yaoundé, Cameroon.

The Lom Pangar dam, the largest reservoir in Cameroon with a storage capacity of 6 km³ and a 30 MW hydropower plant, primarily regulates the hydrologic regime of the Sanaga River to maintain hydropower efficiency during dry seasons and enhance downstream hydropower plant performance. Understanding and managing sediments are crucial for the sustainability of dams, as indicated by numerous studies. This study assessed the granulometry of the sediments transported across the reservoir. For that purpose, 6 samples of fresh sediments were collected in the lacustrine and transitional sections of the reservoir using the standard method. Particles size was assessed using the laser diffusion technic after a 3 mm sieving. Various granulometric parameters were derived from the literature to analyze and characterize those sediments. Results show that silts are more than 70% of particles size and range between 2.19 - 60.26 µm. Size distribution also shows the same trend with D₇₅ less than 51 µm. This is confirmed by the low values of Inman Skewness SkΦ (−0.168 to 0.303). The Sorting index S₀ ranges from 0.31 to 0.53 µm, showing a very well-sorted sediments, aligning with low values of Krumbein index (0.906 - 1.683) that express the low heterometry of the particles. The consequence on the dam will be a quick clogging of the bottom of the reservoir. Their pH varies from 7.0 to 7.5. It also appears that the sandy fraction trend is higher in the right bank of the dam and reaches 22% on the right bank of Pangar River due to crystalline geology. Fraction greater than 3000 µm is negligible. The management of the dam has to keep attention to these results as siltation may close the safety outlet of the dam, damage turbines, and provoke recurrent technical and safety issues. Further, the clogging of the bottom of the reservoir may lead to an ecological problem with the limitation of hyporheic flow. Thus, water exchange with the underground water table and the natural purification of water reduce, while increasing sediments deposits change the biogeochemistry processes.

Lom Pangar Dam, Sediments Granulometry, Sustainability, Hydropower, Dam Safety

Fotie Lele, R., Diminescu, M. A., Ouedraogo, I., D?ncila, A. M., Pelede, S., Emadak, A. and Lompo, M. (2024) Granulometry Assessment of Lom Pangar Dam Sediments (East-Cameroon). Journal of Geoscience and Environment Protection, 12, 207-231. doi: 10.4236/gep.2024.126013.