The application of a tandem dike system in Vietnam

The application of a tandem dike system in Vietnam

Tri, M.C.

Van der Meulen, F.
Verhagen, H.J.
Schiereck, G.J.

TU Delft

2008-06-18

In the low-lying coastal regions coastal defence structures are usually designed with a main function to protect the hinterland from highly vulnerable to coastal flooding. Sea dikes are usually the most common and important elements which form the coastal flood defence system. Sea dikes are designed at a pre-defined circumstance and requirement. For instance, dikes are designed where no overtopping; some overtopping; or large overtopping water is allowed. The most interesting issues at the preliminary design stages of a sea dike are its height and layout and associated overtopping discharge criteria. There have been many discussions on whether sea dikes should be designed high enough to not allow any overtopping water or using relatively low but “strong” dikes in order to allow for some to large overtopping water. First option leads to a very high and big dike as, for example, as in most sea dikes in the Netherlands. The second option needs a transitional area to store the overtopping water or to have a way to release and/or collect the overtopped water as well as a proper resistance of upper and inner parts of the dikes to avoid erosion due to overtopped water. Recently, the ComCoast project develops and demonstrates innovative solutions for flood protection in coastal areas. In which different types of dike cross section and layouts of defensive system were proposed. Concepts of defensive zones are presented beside the already existing concept of defensive lines. However, within the ComCoast1 project, attentions are paid mainly to developments of the innovated concepts rather than focusing on comparison of the proposed system with the conventional sea defences. Thus, there is still lack of guidance and comparative tools to determine the best choice amongst the conventional or innovated options in decision making process. This study focuses on development of the comparative framework and generic guidance to support the decision making process in selection of the best suitable layout option of the sea dike system for a given location. Based on overtopping criteria two situations are considered for the analysis: (i) using one defensive line; (ii) using two defensive lines (defence zone). The multi-criteria analysis, which takes social, economic, environment and technical aspects into account, and the cost-benefit analysis, are used in the selection of the best option. Finally application is made for several case studies of coastal flood defence in Vietnam.

secondary dike
flood management
flood protection
risk analysis

TLE900300

http://resolver.tudelft.nl/uuid:a246c0db-4516-426a-9eee-95dd48ebb8ba

IHE Delft

IHE MSc thesis HECPD0804

Hydraulic Engineering Reports

report

(c) 2008 Tri Mai Cao