Abstract

This study presents the analytical modelling, design, and hydraulic validation of a submersible threshold hydraulic micro-dam for rural hydroelectric production on non-diverted low-head rivers. Installed directly in the river, this micro-dam offers a technically and economically viable solution to meet the growing electricity demand in rural sub-Saharan communities, particularly in the Republic of Congo, while promoting renewable technologies and sustainable development. This work's contribution is the development and validation of a simplified analytical model derived from the 1D Saint-Venant equations, systematically compared with two-dimensional numerical simulations in COMSOL Multiphysics, applied to a case study of the Douni River in the Republic of Congo. The analytical model enables the estimation of flow speed distributions, pressures, and hydraulic power along the micro-dam channels.  Results indicate average flow speeds of 4.46-9.82 m/s per channel, far exceeding the measured river velocity of 0.297 m/s. Hydraulic power outputs of 7.13 kW to 28.96 kW per channel (14.26-57.92 kW for a two-channel system) for water depths ranging from 0.22 m to 0.10 m under supercritical flow conditions. The average relative deviation between the analytical and the numerical simulation results remains below 5%, confirming the validity of the proposed simplified method for preliminary design. These values correspond to a maximum slope of 21.8° (40% per channel) and a minimum drop of 1 m. The submersible threshold hydraulic micro-dam demonstrates potential as an integrated hydraulic-hydroelectric solution for small rivers in rural villages, where conventional flow diversion is limited by the absence of natural slopes and high banks. This study is limited to two-dimensional simulations and uniform steady-state flow assumptions and provides a reliable basis for designing low-cost, sustainable micro-hydroelectric systems for electrification in remote areas.