The CORDEX.be initiative as a foundation for climate services in Belgium

The CORDEX.be project created the foundations for Belgian climate services by producing high-resolution Belgian climate information that (a) incorporates the expertise of the different Belgian climate modeling groups and that (b) is consistent with the outcomes of the international CORDEX ("COordinated Regional Climate Downscaling Experiment") project. The key practical tasks for the project were the coordination of activities among different Belgian climate groups, fostering the links to specific international initiatives and the creation of a stakeholder dialogue. Scientifically, the CORDEX.be project contributed to the EURO-CORDEX project, created a small ensemble of High-Resolution (H-Res) future projections over Belgium at convection-permitting resolutions and coupled these to seven Local Impact Models. Several impact studies have been carried out. The project also addressed some aspects of climate change uncertainties. The interactions and feedback from the stakeholder dialogue led to different practical applications at the Belgian national level

Modelling of fine-grained sediment transport and dredging material dumpings at the Belgian Continental Shelf

The Belgian coastal zone is shallow, well mixed and has a high hydrodynamic energy. In the coastal zone a turbidity maximum occurs, which is responsible for high dredging amounts. Every year about 10x10(6) ton dry matter (TDM) is dredged for the maintenance of the harbours and the navigation channels. After dumping the matter is transported in suspension. The amount of maintenance dredging works is depending on the local hydrodynamic conditions and of the natural sediment transport as well as the amount and frequency of the dumping and dredging works. In order to estimate the efficiency of the dumping sites the natural cohesive sediment transport has to be known. Numerical models can be used to simulate this natural sediment transport. The uncertainties or variability of the sediment transport measurement data are high, in contrast with the dredging and dumping data, which are well known. The natural sediment transport is partly formed by the continuous erosion and deposition during a tide, a neap-spring cycle and during storms. This article will focus on the results of numerical simulations of the sediment transport. In particular the natural sediment transport of mud, the effect of dumping of dredged matter and the efficiency of the dumping sites will be discussed. This discussion is preceded by an overview of the physical situation (hydrodynamics, sediment transport, dredging and dumping data) and a description of the numerical models used (hydrodynamic model, wave model and sediment transport model)

The mud deposits and the high turbidity in the Belgian-Dutch coastal zone, southern bight of the North Sea

The Suspended sediment processes and the mudfields found in the Belgian/Dutch coastal area (Southern North Sea) are discussed by presenting an integrated data-modelling approach of the suspended sediment transport along the Belgian-Dutch coast, using, a fine-grid coupled 2D hydrodynamic and sediment transport model and existing field and literature data. These mudfields and turbidity maxima are situated in a well-mixed, highly energetic hydrodynamic environment. In the past the occurrence of this high turbidity zone (more than a few hundreds mg/l of suspended matter) was ascribed to a closed hydrodynamic system (gyre) in front of the coast. This study shows that the SPM input through the Strait of Dover, the shallowness of the considered area, the decreasing magnitude of the residual transport vectors from the French/Belgian border towards Zeebrugge and the specific hydrodynamic features are the main processes responsible for the presence of the turbidity maximum. The origin and the formation of these mud deposits in front of the coast are explained by the neap-spring tidal cycles and the presence of SPM Sources (import Of SPM through the Strait of Dover and through erosion of clay layers). (C) 2003 Elsevier Science Ltd. All rights reserved

An estimate of the suspended particulate matter (SPM) transport in the southern North Sea using SeaWiFS images, in situ measurements and numerical model results

A study is presented where satellite images (SeaWiFS), in situ measurements (tidal cycle and snapshot) and a 2D hydrodynamic numerical model have been combined to calculate the long term SPM (Suspended Particulate Matter) transport through the Dover Strait and in the southern North Sea. The total amount of SPM supplied to the North Sea through the Dover Strait is estimated to be 31.74 x 10(6) t. The satellite images provide synoptic views of SPM concentration distribution but do not take away the uncertainty of SPM transport calculation. This is due to the fact that SPM concentration varies as a function of tide, wind, spring-neap tidal cycles and seasons. The short term variations (tidal, spring-neap tidal cycle) have not been found in the satellite images, however seasonal variations are clearly visible. Furthermore the SPM concentration in the satellite images is generally lower than in the in situ measurements. The representativness of SPM concentration maps derived from satellites for calculating long term transports has therefore been investigated by comparing the SPM concentration variability from the in situ measurements with those of the remote sensing data. The most important constraints of satellite images are related to the fact that satellite data is evidence of clear sky conditions, whereas in situ measurements from a vessel can be carried out also during rougher meteorological conditions and that due to the too low time resolution of the satellite images the SPM concentration peaks are often missed. It is underlined that SPM concentration measurements should be carried out during at least one tidal cycle in high turbidity areas to obtain representative values of SPM concentration. (c) 2007 Elsevier Ltd. All rights reserved

Morphodynamic evolution of the kink of an offshore tidal sandbank: the Westhinder Bank (Southern North Sea)

This study looks at the complex interactions between sedimentology, morphology and hydrodynamics near a kink in an offshore tidal sandbank (Westhinder) and combines all these data to understand the kink's characteristics. The Westhinder sandbank lies in the northern part of the Belgian continental shelf, where the main hydrodynamical agents are the tidal currents. The data sets include two multibeam surveys, 59 surficial Van Veen grab samples and a hydrodynamical and sediment transport model (set up by MUMM). The different data sets point to a triple division of the kink region. The parts north and south of the kink are covered with larger dunes, culminating at the bank's crest into a symmetrical very-large dune. Here, the bank is actively maintained by a net sediment transport up both bank flanks and by higher residual water transport strengths. The kink part of the bank lies deeper, is characterized by a steeper eastern flank and by a faster and eastward movement of the very-large dunes over both bank flanks. Coarse sediments west of the kink reveal that the peak flood current is hindered by the changing orientation of the bank northward into a more rectilinear N-S position. The finest sediments are found on the lee slope and might be washed out from the kink's stoss slope. A combination of all the results points to a possible breakthrough in the kink, a hypothesis which is worked out into a scheme. (C) 2004 Elsevier Ltd. All rights reserved

Suspended particulate matter dynamics and aggregate sizes in a high turbidity area

Measurements of aggregate size, suspended particulate matter (SPM) concentration and current velocity have been carried.out in the Belgian coastal zone (southern North Sea). Two stations were situated in the coastal turbidity maximum zone; another station was located more offshore at the edge of this turbidity maximum. The data have been collected using a LISST 100, OBS sensors, water samples and a bottom mounted ADCP. Turbulence (Kolmogorov microscale) has been modelled for the same period using a 3D numerical model. The results show that the size of the aggregates is significantly smaller in the coastal turbidity maximum area. The processes responsible for the occurrence of smaller aggregate size in the coastal zone compared with the more offshore location are: the higher turbulence; the smaller time available for the aggregates to grow up to an equilibrium size; the higher deposition of mud, resulting in a break-up of the floes and the lower availability of organic matter, which may limit the size of the floes. (c) 2006 Elsevier B.V. All rights reserved