Kouassi Laurent ADOPO¹, Gheorghe ROMANESCU^2,3,*, Alexis Yao N'GUESSAN¹ & Cristian STOLERIU^2
1Cocody University of Abidjan, UFR des Sciences de la Terre et des Resources Minières, Ivory Coast
²Alexandru Ioan Cuza University of Iasi, Faculty of Geography and Geology, Department of Geography, Bd. Carol I 20A, 700505, Iasi, Romania, romanescugheorghe@gmail.com
³Alexandru Ioan Cuza University of Iasi, ARHEOINVEST - Interdisciplinary Platform, Blvd. Carol I, 22, 700506, Iasi, Romania, *Corresponding author: romanescugheorghe@gmail.com

RELATIONS BETWEEN MAN AND NATURE AND ENVIRONMENTAL DYNAMICS AT THE MOUTH OF THE KOMOÉ RIVER, GRAND-BASSAM (IVORY COAST)

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The mouth of the Komoé River is situated in south-eastern Ivory Coast. The entire shoreline is composed of a sequence of partially or totally closed coastal barriers and lagoons. The maximum depth during the lowest water level is 12 m, but it increases to 14 m during high waters. In 1979, the maximum depth was 18 m. The estuary that communicates with the Gulf of Guinea through a natural opening was permanently blocked due to massive clogging; it is currently a lagoon. The most important hydrotechnical project in the area is the Vridi channel, which was inaugurated in 1951 and is located in the Ebrié lagoon (situated west of the mouth of the Komoé River). This study focuses on the relations established between the dynamics of the aquatic setting and the economic activity conducted by the local population. During the period 2005–2007, the bottom of the Komoé lagoon cuvette suffered extensive erosion or deposition alterations: mean variations of -5 cm were recorded for erosive surfaces and 15–20 cm for deposition surfaces. The channel, which is influenced by fluvial runoff, features three morphological types of riverbed: the "U"-shaped channels are in balance with depositional and erosive agents; the "V"-shaped channel is specific to erosive sectors; the intermediary morphology marks the change from erosion to deposition. A 3‰ increase of the salinity has been recorded. During the period 2006–2007 the total volume of deposited sand was 760,458 m³. The granulometry is directly related to the shape of the particles and decreases upstream to downstream, from 765μm to 240μm. The closure of the opening to the sea and the accentuation of the clogging process at the mouth of the Komoé River require the implementation of new hydrotechnical projects: the artificial reopening of the communication with the sea; the elimination of harmful economic activities (e.g., the semi-wild animal breeding, the elimination of household waste, etc.); channelling the old inlets; refreshing the waters and eliminating the eutrophisation process, etc.