DIKE ENGINEERING - Introduction to Soft Soil Geotechnique: Content, Context and Application - page 310

- Manual Aspects of Clay (1996);
- Manual Asphalt as Cover (2002);
- Manual Classification of Peat (1994);
- Manual Cofferdams and Deep Walls in Water Defence Systems (2004);
- Manual Inventory and Valuing LNC (Landscape, Nature, Culture) (1994);
- Manual Stone Revetments (2003);
- Manual Sand Boils (1999);
- Manual Water Defence Ground Structures (2001);
- Manual Water Pressures in Dikes (2004);
- Manual Wave Run-up and Overtopping (2002).
There is an annual budget of about 100 million euros for a research program to
update the guidelines with a frequency of six years, parallel to the once in six-year
evaluation of all primary dikes and water defence structures. The outcome of the
last three evaluations shows that about 50% of the flood defence is sufficient to
good, about 30% is undetermined (lack of data, lack of knowledge), and about 20%
is insufficient and needs to be improved. After every evaluation a comprehensive
dike-improvement program is defined: for the undetermined a focus on collection
of missing data, and for the insufficient a redesign. For this effort the Dutch
government spends 1 to 1.5 billion euros a year. The work is executed by the water
boards under supervision of the provincial authorities and the ministry in charge.
The lack of knowledge is addressed in the research program. The money spent for
safety looks much, but compared to the national budget and the national product is
not more than a few percent. One may wonder if that is sufficient when the value at
stake is considered. Flooding damage is not easily insurable!
E LATEST DEVELOPMENTS
The thousand-year experience in eliminating high water threat to the Dutch
lowlands is by no means complete and sufficient. A comprehensive study for
coastal zone extension has been completed (Waterman), and progress is made to
natural supported coastal developments at several locations. Observation indicates
that natural sand transport guided by local hard elements creates the planned
coastal zones, in due time.
After the devastating sea storm of 1953, the government installed a Delta
Committee and its advice became the basis for flood protection: a system for
regular dike repair and evaluation, founded in the Water Defence Act. Extensive
works have been performed since, amongst which the Delta project, completed in
1986. The dramatic high river levels of 1993 and 1995, which led to a massive
evacuation have called for a national focus on river dike improvement (the Delta
River project) completed in 2000. In the same period, several weak spots on the
seacoast defence have been improved. Recent information about climate change
with sea level rise and more intense river discharges gave rise to national concern
about flooding safety in the future. The government installed a new Delta
Committee, which came with an integral advice in 2008 that will protect the
lowlands for a long time and calls for working together with the water. The
flooding threat is not acute but yet urgent. The advice is a new Delta program that
comprises twelve recommendations