Physicochemical Characterization at the Drawing and Bathing Points of Lake Kivu, by the Water Quality Index

Abstract

Listen

Translate article

ABSTRACTWater quality assessment in freshwater ecosystems is crucial for understanding their health and ensuring safe water use for various domestic purposes. This study on Lake Kivu highlights the significance of physicochemical parameters in evaluating quality dynamics by the water quality index (WQI). The sampling for physicochemical characterization, including T°, DO, EC, pH, TDS, SiO2−, PO43−, NO3−, salinity, transparency, and chlorophyll‐a, was collected in four campaigns: spatial (seven urban and seven rural drawing and bathing stations) and temporal (quarterly and seasonal), from August 2021 to June 2022, twice per season (rainy and dry). Eight parameters contributed to classifying the WQI, in global gradient, from strong to low of the average water quality. In rainy seasons, Lake Kivu water is slightly more disturbed but without spatially significant differences. WQI correlated significantly with nutrients (r = −0.845 for PO43−, −0.649 for NO3−, and −0.824 for SiO2−; p = 0.000), T° (r = −0.371; p = 0.005), and transparency (r = −0.359; p = 0.007), which are raised and promote toxic algal blooms (particularly Cyanophyceae). Water quality at urban and rural drawing and bathing points is inadequate for sustaining aquatic life. Chemical treatment, disinfection, and rigorous monitoring are necessary for safe use. The correlation between WQI and nutrient levels during the rainy season suggests that improving governance in reducing nutrient inputs into Lake Kivu catchments can sustainably enhance water quality at these use points. Physicochemical parameters are essential, but their standalone analysis often fails to capture water variations adequately. Focusing on these physicochemical parameters related to toxic Cyanophyceae, the biological analysis offers a complementary perspective with a multiparametric approach, including the WHO cyanophycean standards, not used to date, for aquatic life and the health of beneficiaries/users.