Estimación de Producto Regional Aproximado (PRA)

People with special needs have different vulnerabilities compared to those without these needs during evacuation of when exposed to a flood. This section discusses those who can be considered as people with special needs related to a disaster, in section 13.5 the vulnerability is taken into account te define optimal evacuation strategies to minimize loss of life for people with special needs during evacuation and flood events. For people in a wheelchair, it is more difficult to move to upper floors. People who depend on electric instruments for care might need extra attention and support during an evacuation. It can, however, be questioned which people with special needs will require this attention. For example, children and the elderly might be considered as people with special needs, but other citizens can (and will) take care of them during an evacuation when enough time is available (in the case of a threat-driven response). When no time is available (an event-driven response), the support of other citizens might be less, and the group of people with special needs increases.

Dutch research defined people with special needs as people that depend on daily care provided by others or machines. This makes them less self-reliant, and it is assumed that this group cannot evacuate by themselves (Don and de Jong 2008). When elderly and children are also defined as people with special needs about 20% - 25% of the population can be considered as part of this group (VCP 2008). However, in the case of mass evacuation planning for flooding, this number is not accurate because it also depends on the measures taken by other citizens and authorities (see section 13.5).

During the transition phase in the case of a threat-driven response, before the actual start of the evacuation, measures will be taken to prepare for the evacuation. During this period citizens will take measures (collect medicine, valuables etc.) for their own safety, they are expected to return to their homes or gather with their social groups before evacuating. Parents will pick up their children and evacuate with them, families will take care of their elderly family members which might be in nursery homes or hospitals as well. During evacuation due

to flooding, most people evacuate by them self by (their own) car, a minority by public transport or they go to a shelter.

From the perspective of mass evacuation, people without special needs (self-reliant people) are considered as those who are able to evacuate on their own using cars, public transport and the available infrastructure. Also people who can evacuate with them are considered to be self-reliant. People with special needs, or non-self-reliant people, depend on others who offer additional services that cannot be fulfilled by other citizens. Emergency planning by the authorities should focus on a reduction of the people with special needs to be evacuated by the authorities and support those who remain. However, the strategy for the evacuation of this group of non-self-reliant people should be further taken into account. Because of their dependence on care and electrical instruments, which are also limited during an event, problems can arise during evacuation and in a shelter after the evacuation. Taking the probability of flooding into account as well as the size of the threatened area related to the flood, more insight is needed regarding consequences of evacuation of this group. This could lead to alternative strategies for those with special needs to minimise the loss of life. In section 13.5, this is further investigated as a part of adaptive planning.

7.5

Concluding remarks

Most people evacuate themselves, and the authorities facilitate evacuation by offering information and by managing the environment (for example, forms of traffic management and the use of shelters). People with special needs, or non-self-reliant people, depend on others who offer additional services that cannot be provided by other citizens. The evacuation of people with special needs is further discussed in section 13.

Choices about evacuation by citizens are influenced by various forms of information. The information will be gathered using multiple sources, such as the internet, radio, television and social media (with increasing importance). This information (and opinions) is partly distributed by authorities and by the media, (semi) experts and other citizens using (social) media. Information communicated during the threat by the authorities can be used to influence citizen’s response and effectiveness of evacuation.

During the period of the threat, the symbolic value of different calls for evacuation by the authorities (as an advisory or even a mandatory evacuation) can be used as a strategic instrument, to urge people to evacuate and influence effectiveness of evacuation. This information can be used in addition to the limited capacity of emergency services. Other symbols which can be used to influence effectiveness of evacuation are the visibility of first responders or the army and the families of first responders who start evacuating. The use of these symbols is a strategic asset for the authorities to create a sense of urgency and influence the citizens’ response.

The effectiveness of evacuation is related to the capacity and structure of the road network and the number of evacuees (or better vehicles in the evacuation) and their behaviour. Uncertainties in the citizens’ response strongly influence the performance of an evacuation. Citizens’ response cannot be controlled by the authorities, therefore uncertainty has to be taken into account. Measures for the authorities to increase effectiveness of evacuation after detection of a threat are a combination of physical measures to the infrastructure, information communicated to the citizens by the authorities taking the limited risk awareness into account.

It is shown that the citizens’ response (human choices) can reduce the time required for evacuation as well as it can increase the time required for the evacuation of an area. The capacity of the traffic infrastructure gives an upper limit for the performance of the evacuation, and improvements in the citizens’ response are not effective when the road capacity is fully used. The effectiveness of the citizens’ response also reduces for preventive evacuation when lead time reduces.

The (autonomous) response of the public can reduce the efficiency of traffic networks because these become overloaded or are less effective used. Also additional trips as to collect family members cause interference with other traffic streams and therefore increase the time needed for evacuation.

Delta areas and societies have been able to develop social and economic activities based on successful measures to reduce the risk and the probability of flooding. As a consequence the risk awareness decreases because of low frequency of floods. This limited risk perception can be seen as a problem. However, it is also a luxury problem caused by the success of other mitigating measures. The problem can only exist when the risk is reduced and therefore can be seen as a second hand problem. Realistic evacuation planning takes a realistic level of risk awareness into account as a boundary condition. After detection of a threat in most case some lead time is available, during the transition phase authorities can overwhelm the society with information by providing adequate information based on the actual circumstances and related measures.

Further improvements in the citizens’ response among those who shelter in place or who are hit during an evacuation (and escape or are rescued) can contribute to lower mortality rates.

PART III

RATIONAL

DECISION MAKING

FOR EVACUTION

AS LAYER OF

FLOOD RISK

MANAGEMENT

8

Introduction in cost-benefit