Characterisation of the morphology of Cavally River sediments in a context of anthropisation at Zouan-Hounien (West-Côte d'Ivoire)

The aim of this paper is to characterize the bottom sediments of the Cavally River bed in order to determine the appropriate roughness coefficient of said river, in a context of clandestine gold panning in the locality of Zouan-Hounien. To achieve this, fifteen (15) sediment samples are periodically taken from the Cavally River bed, precisely in the area of influence of the activities of the Société des Mines de Ity (SMI). These samples are taken from the Bakatouo meander (upstream) to downstream of the Colline Sud meander. Sediment sampling is done with a Van Veen grab sampler. The collected sediments are carefully preserved in labeled bags. The granulometric analysis of these sediments is carried out at the laboratory using a column of sieves with AFNOR series. Analysis of the particle size curves of all samples suggests that Cavally sands are generally medium to heavy. Moreover, these particle size curves could show that the sands are transported mainly by bedload. However, these observations should be taken with great caution, since gold mining activities have a very great influence on the distribution of sediments in the river.