Cities will most likely be dealing with more flood-related events in the future due to climate change. It is important to understand the short-term and long-term impacts of such events to be able to improve the resilience of these cities.

Indirect impacts

Flooding can have both direct and indirect impacts. When critical infrastructure floods, this often has indirect effects larger than the initial damage. If one feature gets flooded, it can set in motion a cascade of effects affecting many other features.

CIrcle – 3Di combination

With the stakeholder-tool CIrcle knowledge on critical infrastructure can be gathered from different stakeholders in an area. This is combined with the high-resolution hydraulic model 3Di to simulate a flooding scenario, making use of a variable-size computational grid combined with high-resolution underlying input data. The combination of the extensive stakeholder-backed-up information and the high spatial and temporal resolution of the model results allows for a detailed analysis of cascading effects. A first analysis of has been conducted for North Rotterdam.

What happens if a dike breaches in Rotterdam?

Many indirect effects take place: already in the first hours the metro network floods, the railway network cannot be used due to embankment instability, and the C2000 emergency communications network is affected. Subsequently several main power stations are affected, causing outages largely outside of the flooded areas. Several hospitals will be in need of emergency power supply or will have to be evacuated. In a few days the flood and the outages are merging to the north, making it unavailable for potential evacuation. Drinking water supply might be affected when water pumps of high buildings stop working because of the electricity outages. The lack of drinking water will quickly become a problem in a highly populated area like Rotterdam.

For a description of the application of these concepts, download the ACC report on “Adaptation to Climate Change: Cascading Effects” here