Determination of bed roughness parameters from field survey: application to the Cavaillon River, Haïti

Carlier d'Odeigne, Olivier [UCL] Soares Frazao, Sandra [UCL]

(eng) The Cavaillon is a Southern Haitian River causing considerable management problems since its behavior is uncertain and likely to cause serious damage to surrounding populations. Within the framework of a scientific cooperation project, our willingness is to improve the ability of local institutions to manage the river. Therefore, a methodology to construct a complete hydraulic model of the river is developed by implementing methods that require few resources. This paper presents the definition of the roughness parameters. Definition of the flow resistance evolution remains a key element in the characterization of a fluvial system in order to achieve a 1-D or 2-D modeling of the flow. Data were collected from a bed materials survey carried out for 84 cross-sections to predict the bed roughness parameters through the empirical equation proposed by Ferguson. The focus is on the determination of a parameter representing bed roughness variation along the sections, but also depending on the discharge. With these parameters, a stage-discharge relation is built for two monitoring sections, aiming the use of future available in-situ measurements. Finally, a distribution of the bed roughness along the 20km reach is proposed as a function of the flow discharge.