Effect of drying on the physico-chemical characteristics of the waters of tributary streams of Alibori and Sota rivers in northern Benin

Abstract

The objective of this study is to measure the physico-chemical impacts of the drying up of the tributaries of the Alibori and Sota rivers in northern Benin. Physical parameters were measured in situ in the waters of five streams (Bouli, Irané, Tassiné, Sanson and Yassikoga) and chemical parameters were measured in the laboratory. The results showed differences in the values of the physico-chemical parameters between before drying (T°C:19.3 and 23.9°C), pH (6.7 and 7.8), TDS (8.5 ppm and 20.5 ppm), NH4+ (0.075 and 0.5 mg/l) and P2O5 (0.07 and 0.16 mg/l) and after drying (T°C: 26.5 and 33.6 ° C), pH (3.2 and 6.5), TDS (26.5 and 30.1 ppm), NH4+ (0.3 and 0.57 mg/l) and P2O5 (0.07 and 0.16 mg/ l). The seasonal difference in these values reveals the adverse effects of drying on the physico-chemical parameters of the waters in the study environments. Among the five streams studied, Yassikoga presented the warmest water, the most acidic, the more turbid, with a higher concentration of NH4+ ion and P2O5.

Keywords: River drying, Physico-chemical characteristics, Tributary streams, rivers, Alibori, Sota, North Benin