Risk and coastal zone policy: example from the Netherlands

A definition of risk:

Various definitions of risk exist which can be applied to different situations and which often involve a degree of subjectivity. All known definitions of risk however have one element in common: the distinction between reality and possibility (Renn, 1998). A definition of risk contains three components, viz. (1) an outcome that has an impact on what humans value, (2) the possibility of occurrence (uncertainty) of an event and (3) a formula to combine both elements (Renn, 1998). In other words, risk can be described by a mathematical function of the probability of an event and the consequences of that event (Jonkman et al. 2003). In many cases, risk is defined as the probability of occurrence of a disaster (natural or human induced) times the economic damage as a result of the disaster.

Often, the terms risk and uncertainty are used in the same context. There is however a clear distinction between risk and uncertainty. The term risk can be applied to describe situations for which probabilities are available to describe the likelihood of various events or outcomes. If probabilities of various events or outcomes however, cannot be quantified, or if the events themselves are unpredictable, the term uncertainty can be applied (Loucks & Van Beek, 2005).

Risk in the coastal zone:

The concept of risk can be applied to many different situations. Divisions are made between individual, societal, economic, environmental and technical risks (Bickerstaff, 2004). In most coastal zones around the world, the risk of flooding poses a threat to present and future activities. Here, risk is the probability of occurrence of an extreme storm event leading to flooding and erosion, multiplied by the economic damage caused by the storm event. It is important to note that in this case, the probability itself does not necessarily involve risk. If the area prone to the effects of extreme events is free from any socio-economic activities, risk will be reduced to zero.

Risk and coastal zone policy in the Netherlands:

Safety standards are imposed to the area behind flood defense structures, i.e. dunes and dikes, to minimize the effects of possible extreme events and hence, to reduce the risk in these areas (RIKZ, 2002). Dunes and dikes along the Holland coast (i.e. the provinces of Noord-Holland and Zuid-Holland) should be able to withstand the effects of a storm which has a probability of occurrence of once per 10.000 years. So-called erosion lines are determined, which indicate how far erosion might reach landward as a result of the storm.

Along the Dutch coast however, socio-economic are also located in front of the flood defenses, and as result safety standards do not apply in these areas. People who live and work in this area do so at own risk.

Risk will continue to increase in the future. Climate change and the associated rise in sea level and increase in severe storm conditions enhance the probability of occurrence of an extreme storm event. In addition, due to sea level rise, erosion lines will shift in a landward direction. Furthermore, the effects in terms of (socio-) economic damage increase as well, not only as a result of the increased probability of a storm event, but also due to ongoing socio-economic activities, which demand more and more space in the coastal zone. Therefore, it is of great importance to gain insight in how different socio-economic activities can adapt to the long-term and large-scale (km2’s) natural coastal dynamics.

Present day Dutch coastal zone policy (CPD, 2000) pursues maintaining safety on the long-term (sustainable safety) and improving spatial quality in the coastal zone. Coastal safety policy and measures should involve a time horizon of 200 years.

References:

Bickerstaff, K. (2004). Risk perception research: socio-cultural perspectives on the public experience of air pollution, Environment International, 30, 827-840

CPD. (2000). “Traditie, Trends en Toekomst, 3rd Coastal Policy Document,” Ministerie van Verkeer en Waterstaat, pp. 122

Jonkman, S. N., van Gelder, P. H. A. J. M., Vrijling, J. K. (2003). An overview of quantitative risk measures for loss of life and economic damage, Journal of Hazardous Materials, A99, 1-30

Loucks, D. P. and van Beek, E. (2005). Water Resources Systems Planning and Management An Introduction to Methods, Models and Applications, UNESCO and WL|Delft Hydraulics, ISBN 92-3-103998-9

Renn, O. (1998). The role of risk perception for risk management, Reliability Engineering and System Safety, 59, 49-62

RIKZ (2002). Towards an Integrated Coastal Zone Policy, Policy agenda for the coast, National Institute for Coastal and Marine Management/Rijkswaterstaat-RIKZ, pp. 48