Author(s)

Shyrland Dave Bibi^1,2, Jean Armand Paka^2,3, Rene Josue Samba¹, Jean Bienvenu Dinga^2,4, Christian Tathy^1,5, Ernest Amoussou^6,7

¹Laboratory of Mechanics, Energy and Engineering, Higher National Polytechnic School, Marien Ngouabi University, Brazzaville, Republic of Congo.
²National Institute for Research in Exact and Natural Sciences (IRSEN), Hydrology Laboratory, Brazzaville, Republic of Congo.
³Faculty of Letters, Arts and Human Sciences, Physical Geography Laboratory, Marien Ngouabi University, Brazzaville, Republic of Congo.
⁴Faculty of Sciences and Techniques, Department of Environmental Sciences, Marien Ngouabi University Brazzaville, Republic of Congo.
⁵Department of Exact Sciences, Higher Teacher’s Training School, Marien Ngouabi University, Brazzaville, Republic of Congo.
⁶Faculty of Letters, Arts and Human Sciences, University of Parakou, Parakou, Benin.
⁷Pierre Pagney Laboratory, Climate, Water, Ecosystem and Development (LACEEDE), University of Abomey-Calavi, Cotonou, Benin.

The analysis of the risk of flooding upstream from the Imboulou hydroelectric dam on the Léfini River in the Republic of Congo-Brazzaville, focused on the evolution of annual rainfall and flow in the study area during the period from 1970 to 2020 before and after the building of the dam in 2005, by applying statistical methods. These methods were used to analyse the spatial and temporal evolution of rainfall and flow at the unique hydrometric station located at the RN2 (National Road N°2) bridge in the village of Mbouambé in the Pool region. This work has shown that rainfall is not the cause of flooding in the Léfini catchment area. The monthly flow coefficient (MFC) showed exceptional flooding from November and December onwards after the dam was built, resulting in a variability of flows, with periods of high and low water. In addition, the annual average flow (AAF) and the maximum average flow (MAF) increased after the dam was built. Maximum average flows (MAF) were higher than annual average flows (AAF) throughout the period of study (1970-2020). The annual and monthly rainfall-runoff relationship showed changes after the dam was built, particularly from 2009 and during the months of November and December.

Léfini River, Imboulou Hydroelectric Dam, Floods, Monthly Flow Coefficient, Annual Average Flow, Maximum Average Flows

Bibi, S. , Paka, J. , Samba, R. , Dinga, J. , Tathy, C. and Amoussou, E. (2023) Analysis of Flood Risks Upstream from the Imboulou Hydroelectric Dam on the Léfini River, a Tributary of the Right Bank of the Congo River. Open Journal of Modern Hydrology, 13, 259-275. doi: 10.4236/ojmh.2023.134015.