Complex systems are notoriously difficult to deal with. Coastal areas are complex social-ecological systems, characterized by a constant change. Floods, storm surges and erosion are natural processes, turning into hazards when assets placed at the coast are at risk. Only with the assets at risk, hurricanes, floods or other natural hazards can have a severe impact on socio-economic systems. In these situations Disaster Risk Reduction (DRR) measures are needed to reduce the risk or the impact.
DRR measures aim to reduce and manage the risks that storms, floods and erosion pose to human health, the environment, cultural heritage and economic activity. Acknowledging that coastal systems are complex, these measures cannot be seen solitarily. Proposing certain DRR measures, coastal managers have to consider side-effects that these measures always bring along. Before undertaking a measure the interdependence of all parts of a coastal system has to be investigated comprising local and regional dependencies.
For example if a beach nourishment is undertaken at a certain part of a beach, this will affect the area where the sand if excavated, the stretch of beach itself where the replenishment is undertaken and adjunct coastal areas where the process of sand drift could lead to sand accretion. Even if the decision is taken not to do anything that will have an effect on surrounding systems (for example in a declining shore line, or collapsing cliffs).
The situation will become even more complex, when we analyze the human usage of coastal systems. Conflicts can arise by using coastal space and resources for different purposes, cumulating when resources are used by different actors. Competition, antagonistic perceptions and attitudes of stakeholders, from local to transboundary levels, will complicate the situation. When taking decision about DRR measure, coastal manager therefore should not only closely study the spatial patterns of the case study area but also have attitudes and values of the different stakeholder in mind.
To plan the activities carefully is one important step to deal with complex risk situations in coastal areas. There are already several ways how to deal with these risks in a more holistic approach, for example there is the concept ICZM (integrated coastal zone management), the concept of maritime spatial planning, or flood risk management.