Page 11 - Identifying cascading effects on vital objects during flooding

2.2. Implementation

As mentioned earlier, it is important to understand the short-term and long-term impacts of such
events in order to improve the resilience of cities and to better understand the impacts of flooding.
To that end, we need to be able to distinguish between direct and indirect impact.

The first step to identify indirect impacts is to understand the cascading effect that is often larger
than the initial direct damage. That is, flooding can set in motion a cascade of effects influencing
many other features. For example, flooding can trigger outages in the electricity infrastructure. That
in turn may cause water and sewage pumps to fail leading to water and sewage system outages.

Figure 3: Impact and Cascading Effects

The flood scenario for Rotterdam was used to calculate direct damages to critical infrastructure
networks caused by the flood, as this damage can expand to other dependent networks.

Stakeholder workshops were conducted to assess direct and indirect impacts including the
cascading effects. The matters discussed includes and not limited to the relationship between
electricity and: emergency communications (can last 4 to 8 hours), the railway transport and how
to communicate with the operators, hospitals, etc. Analysis can be found here which simulates the
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cascading effects for Rotterdam in a short movie with respect to time frame.

Another example of the cascading effect can be found on Cork- an Ireland city. The video is
available here .
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