Assessing climate change impacts on flooding risks in the Belgian coastal zone

Within the scope of the Belgian project CLIMAR an attempt is made to develop an evaluation framework for adaptation scenario’s as a response to the climate change induced impacts in the North Sea area. Primary effects are direct consequences of climate change such as sea level rise, erosion, changes in temperature and precipitation and increased storminess. Secondary impacts are direct and indirect results of the primary effects on different sectors. A first phase of the project consists of identifying and scoping the secondary impacts on ecological and social-economic activities. In this paper results will be presented regarding the secondary impacts of flooding only.Climate change induced primary effects such as sea level rise and increased storminess lead to higher risks of flooding of low-lying coastal areas. One of the most significant social secondary effects is the number of people at risk due to flooding. An important economical effect of climate change is the amount of damage costs. Besides direct damages there will also be indirect economic results such as temporary suspension of production and loss of jobs. Other ecological effects of increased flooding risks are the loss of beach and dune area, as well as associated specific habitats such as wetlands. Indirectly this leads to loss of biodiversity.The magnitude of the most significant secondary effects is quantified by carrying out risk calculations. For each of the sets of the changing physical parameters a related storm scenario is statistically determined. In a first approach, the flooding risks during an extreme storm under present climate conditions and sea level rise are estimated. By means of a set of numerical models the areas susceptible to flooding in the Belgian coastal plain are identified. The resulting flooding risk maps are then used to estimate the scope of the secondary impacts

Slibbalans-Zeeschelde: deelrapport 3.Literatuurstudie

This literature review is a deliverable within the study "slibbalans Zeeschelde" (WL Project 00_029), and gives an overview of available knowledge on mud transport and stock in the Scheldt estuary. It is meant to be used as a reference and an inventarisation of available knowledge on the mud balance of the Scheldt estuary. Sometimes a claim by an author may have come at odds with more recent insights in system behaviour. The authors have tried to indicate that in the text. Because insights are constantly evolving, this document should be a living document.First, available methodologies to estimate mud transport are presented. Anthropogenic activities in the Scheldt estuary that had a possible impact on the mud dynamics are listed. The main part of this literature review consists of a summary of the most important conclusions of literature describing the mud stock in the Scheldt estuary since 1964 and an overview of historic estimations of mud transport and sedimentation over time in different parts of the estuary.For the sake of consistency, mud quantities are converted to Ton Dry Matter whenever possible (TDM in English, Ton Droge Stof or TDS in Dutch), which correspond to the mass of the grains of sediment in the water-sediment mixture

Windows in the dunes - the creation of sea inlets in the nature reserve de Westhoek in De Panne

The Flemish Nature Reserve 'De Westhoek' constitutes together with the French public domain 'La Dune du Perroquet' a transborder coastal dune area of 700ha, situated between De Panne (Belgium) and Bray-Dunes (France). From high-tide mark to polders, the range of dunes has a width of nearly 2km. In the 1950s heavy storms beat a breach through the foredunes of 'La Dune du Perroquet'. Consequently, the seawater could penetrate through the breach into a dune slack during high high tides. This phenomenon is called a 'sea inlet', or a 'slufter'. The seawater could also top over the foredunes of the Belgian 'Westhoek' in those days (during storm tides), but at the end of the 1970s a concrete dunefoot revetment was built in front of the foredunes to prevent further coastal erosion. Sea inlets in the dunes are a rare phenomenon along the sandy coasts of the southern North Sea. They usually harbour a highly specialised bird life and salt-tolerant flora. The management plan for the Nature Reserve 'De Westhoek' that was approved in 1996, includes the creation of sea inlets by locally removing the concrete dunefoot revetment. As the coastal protection policy of the Flemish Regional Authority has evolved to a more dynamic and risk-based approach, the Coastal Division decided to create two sea inlets. Projects that have an influence on the hydrological system of natural areas are however subject to an Environmental Impact Assessment, so that an EIA had to be drawn up for the creation of two sea inlets. After the approval of the EIA by the competent authority and the delivery of a building permit, the works were carried out between January 2004 and June 2004. The two new sea inlets' surface totals approximately 1ha. The deflation zones where the sea inlets were created consisted originally of sandy plains that were thickly strewn with debris from demolished blockhouses and had a scarce Marram-grass (Ammophila arenaria) vegetation. The creation of sea inlets should allow the development of the natural habitats of the annex I of the European Habitat-directive '1310 (15.11) Salicornia and other annuals colonising mud and sand' and '2110 (16.211) Embryonic shifting dunes', and also offer breeding opportunity to at least Kentish Plover (Charadrius alexandrinus) and Great Ringed Plover (Charadrius hiaticula). The results and effects of the sea inlets on the salinity of the groundwater is being meticulously monitored

Sediment budget for the Belgian coast: final report

In the framework of the Vlaamse Baaien project, Flanders Hydraulics Research developed a sediment budget for the nearshore Belgian coast. The study describes the sediment volumes available in the coastal system and their circulation patterns. The sediment budget equation takes into account all the sources and sinks of sediment for each of 9 longshore coastal cells, delimited based on the gradient or disruption of sediment transport. The onshore limit is usually delineated by the coastal defense structures, while the offshore limit is either the closure depth or the offshore limit of data availability. A custom tool was developed to solve the sediment budget equation for each cell. This study also estimates the uncertainties in the data and methods used. The final budget spans a ten year period, between 2000 and 2009. Most inputs to the sediment budget, such as human interventions and bathymetric and topographic data, were developed in previous studies. Other inputs, such as the closure depth, volume changes, and uncertainty of the data and methods were computed in the present study. Longshore sediment transport was calculated empirically and compared to numerical modeling results from previous studies. The latter was ultimately used in the sediment budget. The loss of sediment at the onshore boundary by aeolian transport was assumed to be very small compared to the sediment exchange at the offshore boundary. A sediment budget was built based on the change between the survey at the beginning and at the end of the considered period (2000 – 2009) considering all volume measurements, corrected and uncorrected for human interventions. However, a second sediment budget based on the linear trend was made in order to check the sensitivity of different method of calculation for the volume differences. The Belgian coast is generally balanced in terms of loss and gain of sand, with relatively little exchange to the offshore areas. The exception is in the vicinity of Zeebrugge Harbour, where large volumes of sand are exchanged with deeper offshore areas. Finally, recommendations are made about how to increase accuracy of the sediment budget in the future, including quantifying aeolian sediment transport, measuring closure depth, and extending the sediment budget to the entire Belgian shel