Modelling the suspended sediment dynamics of a large tropical river: the Upper Niger river basin at Banankoro

✍ Scribed by Cécile Picouet; Benoît Hingray; Jean Claude Olivry

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 169 KB
• Volume: 23
• Category: Article
• ISSN: 0885-6087
• DOI: 10.1002/hyp.7398

✦ Synopsis

Abstract

A 9‐year sediment transport monitoring programme on the Niger River was used to study the relationship between suspended sediment concentration and river discharge. During annual floods, this relationship shows the hysteresis normally observed on tropical rivers. This paper presents an attempt to model the time evolution of suspended sediment concentrations during floods using only water discharge data. Two models have been developed. The first model is an empirical model based on a statistical approach using two relationships, one for the rising stage period and one for the recession period of the annual flood. The second one, a lumped conceptual model, uses the respective contributions of two sediment reservoirs. The first reservoir is limited in size and period of functioning and represents hillslope erosion observed during the runoff season. The second reservoir is unlimited in terms of both its size and period of operation and represents sediment contributions from bank erosion and remobilization of sediment deposits in the channel network. Both models have been applied to the Banankoro gauging station on the upper Niger River (for the hydrological years from 1991/1992 to 1999/2000) and are able to simulate the time evolution of sediment concentration during the annual cycle, with a reasonable degree of accuracy. For annual sediment yield, the models do not provide a better estimate than a simple regression with annual water volume. However, the two models are able to simulate the evolution of the sediment flux during the flood. Copyright © 2009 John Wiley & Sons, Ltd.