HYDRODYNAMIC SEDIMENTARY OF THE MIDDLE DELTA OF THE OUÉMÉ RIVER IN THE CONTEXT OF THE CURRENT FLOODS

A.R.M.A ADECHINA, C.N. KELOME, J.B. HOUNKPE

Abstract


Inter-annual fluctuations in rainfall over the last three decades have been associated with the recurrent floods in Ouémé estuary. The purpose of this work is to analyze the water and sediment flows and their conditions for remobilization of sedimentary deposits during floods. In September 2016, the characteristics of the water were measured with multipara meter and turbid meter, liquid flow rates with the aDcp current meter. Suspended sediment (MES) and bottom sediment were collected for particle size analysis. Water sampling was resumed in March 2017 and the MES of all waters was analyzed by spectrophotometer. The water flow in September was 617 m3/s in Bonou and 572 m3/s in Adjohoun. MES, turbidity, and shear rate are higher in September, more importantly in Adjohoun than Bonou. The aforementioned flows were sufficient to remobilize sediments having a median d50 less than 0.1 mm. This remobilization is indicated by an increase in sediment flows from 46.3 Kg/s in Bonou to 55.6 Kg/s in Adjohoun.

Keywords


Ouémé, flood, water flow, sediment flow, remobilization.

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