Unstructured-mesh Modelling of the Hydrodynamics of the Congo River Estuary and Adjacent Coastal Zone
(2015) Marine Environmental Monitoring, Modelling and Prediction — Location: Liège, Belgique (4.May.2015)
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- With the second largest river outflow and one of the widest hydrological basins in the world, the Congo River is of major importance both locally and globally. However, relatively few studies have been conducted on its hydrology, as compared to other major rivers such as the Amazon, Nile, Yangtze or Mississippi. The Congo river-estuary-coastal sea continuum was modelled by means of the unstructured-mesh, finite-element model slim (sites.uclouvain.be/slim). Two-dimensional discontinuous finite-element methods were used, which are similar to those already implemented in the Scheldt (Belgium, The Netherlands) and Mahakam (Indonesia) land-sea continua. In any modelling work, scarcity of data is an issue. But, as the Congo River and Region of freshwater influence is a very remote area, collecting data is even more challenging than usual. For instance, some area are simply unobserved. While applying slim to the Congo River and adjacent coastal zone, we developed tools and procedures to take advantage of as many sources of information as possible. These tools can use any kind of image, georeference it, and then exploit any information it contains. Then, the extracted data can easily be merged with other sources. This model being now up and running, we have made the best use of every remaining data to validate it. The most abundant source of information in this area is satellite tidal analysis. Therefore, the main validation we made is comparing runs of our model with these satellite data and some tidal gauges measurements. As the model results were found to be in fairly good agreement with the available measurements, the hydrodnamics was investigated by computing the age of the water, that is the time elapsed since leaving the upstream, riverine boundary of the domain. The velocity field exhibits quasi-permanent gyres in the estuary and the coastal zone, the origin of which is still unclear. A sensitivity analysis suggests that these gyres, whose size is about half the width of the estuary (i.e. a few kilometers), could be due to the peculiar bathymetry of the navigation channel that has been made a few decades ago.
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Le Bars, Y., Vallaeys, V., Deleersnijder, E., & Hanert, E. (2015). Unstructured-mesh Modelling of the Hydrodynamics of the Congo River Estuary and Adjacent Coastal Zone. Marine Environmental Monitoring, Modelling and Prediction, Liège, Belgique. https://hdl.handle.net/2078.5/193775