DIKE ENGINEERING - Introduction to Soft Soil Geotechnique: Content, Context and Application - page 307

Recently, the approach of dike building is changing because of a growing
awareness that the protected assets are not the same everywhere, and the cost of
ever improving dike systems should be looked at. The approach is characterised
by: inundation risk = inundation likelihood K consequences (damage per dike

ring), see Fig 17.7c.

OVERRUN OVERRUN OVERRUN

STRENGTH STRENGTH STRENGTH

LOADING LOADING LOADING SLIP FAILURE SLIP FAILURE SLIP FAILURE

DAMAGE EFFECT DAMAGE EFFECT

PIPING PIPING PIPING

Figure 17.7c Latest development of the risk approach on flood protection

This inundation approach requires the evaluation of the economic, social, and
cultural damage caused by inundation. It requires awareness for natural and
environmental values and a social acceptance of a change of the role that existing
water-defence systems may play. A serious social-political problem yet to solve is
how to cope with the principle of equity in the constitution and the different
probability of drowning in the various dike-rings, and how to manage with the
valuation of the difference of the economic value in the various dike-rings, from 6
to 30 billion euro (total is estimated at 280 billion euro and the dike-ring average is
about 10 billion euro). The amount of potential damage should become, in fact, a
guiding principle for the effort one should implement to keep the probability of this
failure low. The calculation methods and decision models will define how the
information obtained can be used to make a rational decision. This concept is
defined as: inundation safety = boolean (inundation risk < accepted inundation
risk). Mere intuition and experience have in the past, addressed uncertainties.
Today, it is possible to more objectively quantify and qualify uncertainties for yet
inexperienced but well-described scenarios. Societies call for this approach
confronted as they are with climate change and an increasing pressure on space
allocation for work and living for a growing population with altering needs. In the
coming decades the Dutch will face the issue how to handle uncertainties in an
integral policy and decision making process for a prosperous development of their
lowlands.

D STATE OF THE ART
After completion of the Delta-river project, a workshop was organised to
identify needed innovation directions, in an open discussion in the style of the
British parliament. In introductions, sharp inspiring statements on social versus
scientific matters were prepared to stimulate a debate. Over eighty delegates from
building, government and education communities participated as 'civilian' seated
in the society bench, seated opposite in the scientific bench, or in the public seats
behind a jury. The discussion took place between society and science, the public