Evaluation de l’impact de la montée du lac Tanganyika par la détermination de l’indice de la qualité de ses eaux de surface : Cas de la zone de captage de la REGIDESO
| dc.contributor.author | Nshimirimana, Jean Pierre | |
| dc.contributor.author | Sous la direction de : Dr Nkurunziza Rémy Marie | |
| dc.date.accessioned | 2026-04-24T08:18:48Z | |
| dc.date.available | 2026-04-24T08:18:48Z | |
| dc.date.issued | 2026-03 | |
| dc.description | Mémoire présenté et soutenu publiquement en vue de l’obtention du diplôme de Master en Sciences, Spécialité : Enseignement de la Chimie | |
| dc.description.abstract | Lake Tanganyika has long experienced fluctuations in its surface water levels (Bergonzini et al., 2002 and IGEBU, 2024). As these waters are essential to the life of any ecosystem, maintaining their quality is a major concern for a society that must meet its diverse water needs (Talhaoui et al., 2020). To contribute to monitoring this water quality, we conducted a study assessing the impact of the 2024 rise in Lake Tanganyika's water level by determining the Water Quality Index (WQI) of its surface waters in the REGIDESO catchment area. Twenty-five physicochemical parameters, including heavy metals, were analyzed, and fourteen were selected for calculating the WQI. Samples were collected in June, August, and October 2025 at site 1 (upstream) and site 2 (downstream). Water analysis showed thermal stability within acceptable limits, with temperatures ranging from 27.62 to 29 °C, but this was offset by a concerning alkalinity: the pH, varying from 8.79 to 9, consistently exceeded the standard of 8.5, creating a basic environment likely to disrupt biological balance. This high alkalinity is closely linked to exceptional mineralization, as evidenced by the electrical conductivity (609 and 653 μS/cm), more than double the standard of 300 μS/cm (WHO, 2022). Although the TDS levels remained below the threshold of 500 mg/L, their intensity confirmed a significant presence of salts. Ionic analysis revealed that this mineralization was driven by HCO3- concentrations of 270 mg/L, exceeding the standard of 120 mg/L (WHO, 2022). The potassium (K+) content showed extreme values between 86 and 91 mg/l, thirty times the standard, suggesting a direct impact from upstream agricultural or industrial discharges. As for the organic load, an indicator of organic pollution, the results presented a striking contrast. Although the organic matter (OD) remained satisfactory above 6 mg/l, the BOD5 frequently exceeded the standard by 5 mg/l, peaking at 9.74 mg/l, and this excess indicates significant organic pollution. This can also be explained by the very low transparency of the lake waters (1.20 m at site S1 and 4.50 m at site S2) compared to that of Dubois (1958), where it reached 20 m. The interpretation of the Water Quality Index (WQI) confirms a clear correlation between the sites from June to October. The waters of S2, with a WQI ranging from 42 to 48, exhibited good quality (Class II), despite slight degradation, while those of S1, with a WQI ranging from 58 to 64, displayed average quality (Class III). This assessment reveals a complex dynamic where natural characteristics and significant anthropogenic influences intertwine; Hence the need for regular scientific monitoring following fluctuations in the surface water levels of Lake Tanganyika. | |
| dc.identifier.uri | https://repository.ub.edu.bi/handle/123456789/2270 | |
| dc.language.iso | fr | |
| dc.publisher | UB: FSE | |
| dc.title | Evaluation de l’impact de la montée du lac Tanganyika par la détermination de l’indice de la qualité de ses eaux de surface : Cas de la zone de captage de la REGIDESO |