With accelerating changes in climatic conditions , decision-makers are facing the challenge of protecting human lives and precious assets against flooding from extreme precipitation, sewage outfalls, river overflows, sea level rise and storm surges.
Fortunately, expert assessment and application of advanced modelling can support decision-makers in their response to the complex challenge posed by flooding in coastal regions.
Taking this into account, we asked Nils Drønen, Chief Coastal Engineer at DHI, a few questions about the core advantages of expert knowledge and application of models to support decision-makers in predicting and preparing for future flood events.
Q: What are the core challenges decision-makers are facing when it comes to coastal flooding?
When talking about flooding, it is closely related to enhanced risks and changing climatic conditions. Decision-makers have limited knowledge and overview of what will happen (and what could happen). On a global scale, gradually increasing sea levels and storm surges are affecting many urban areas located near coasts. This steady increase in water levels – sea level rise – will extend over a long period, which means the real trouble may not start to appear until 50-100 years from now. In this uncertain perspective, decision-makers find it difficult to get a tangible feeling of what will happen and when to act. In urban areas, the need for simultaneous handling of water from different sources such as precipitation on land or overflow from sewage systems comprise a complicated flood risk picture that needs to be assessed in its totality when mitigating flood events.
Q: How can expert knowledge and model-based support make it easier for decision-makers to prepare for flooding and climate change?
Advanced hydraulic models can simulate different scenarios. For example, you can test what will happen if sea levels rise and more frequent storm surges affects urban areas. By doing so, you get a better idea of the consequences one might face in the future, and you can quantify different negative impacts caused by flooding. Using advanced model techniques, experts can help decision-makers calculate potential impacts and damages of storm surges and compound events several years from now and simulate what the situation would look like if no action is taken. In this regard, the models can be used to predict future scenarios and e.g. investigate if there is a tipping point around the corner where one might experience severe damages to valuable houses and infrastructure (and hence extreme economic losses), negative impacts on population health and safety as well as potential damages to ecosystems in the area.
Based on this information, decision-makers get expert advice on which mitigation measures to introduce, such as building dikes or installing pumps. Thereby the effect of climate adaptation plans can be tested, and the estimated value gain of a given mitigation plan can be compared with the investments that goes into implementing the given mitigation measures.
Q: How do decision-makers benefit from DHI’s services and knowledge?
DHI not only possesses a deep understanding of the technical aspects of a given situation, but also a very good understanding of different stakeholders’ dilemmas. Our experts are used to working in transdisciplinary settings where local managers, urban landscape architects and economic experts collaborate to help private and public stakeholders protect their assets. This collaboration sometimes includes co-development of protection schemes and development of urban values. With this combination of knowledge and insight, DHI can help translate the technical findings and facilitate down-to-earth understanding and decision-making.
Adding to this, DHI’s model technologies are easily linked to weather and climate projection data and can hence be applied to simulate complicated flooding challenges under projected future conditions. This makes it possible to not only simulate coastal flooding but also the effects in areas near the coast if, for example, a nearby river floods due to limited drainages capacity caused by high water levels during a storm surge. The models can be set up to investigate dynamic effects on the scale of houses and streets as well as taking into consideration extreme flood events being dynamic and coming from multiple sources. The models can be set up to be coupled with other models for different physical, chemical and environmental phenomena, e.g. in the case of spreading of toxic substances from spills and overflows (endangering human health and ecosystems). Sophisticated simulations can show how water flows into the urban area in time and space, and how infrastructure is impacted not only by inundation during floods, but also damages associated with impact from forces due to waves impinging and currents eroding.
Q: How can the services support both long-term and short-term planning?
In cases where you are planning long-term permanent investments such as new infrastructure to prevent flooding, you could also consider how the risk of areas being flooded can be reduced by integrating emergency planning in the decision. This could be in the form of ‘what if’ scenarios or by deploying tailor-made web-based solutions for early warning. The same type of modelling used for long term analysis can be used to support emergency operations, reducing acute risks that are not at a given point in time covered by permanent structures. In this way, the model tools allow for the integration of short-term emergency planning with long-term strategies of, for example, permanent flood prevention.
Protect marine and coastal environments with nature in focus
At DHI, we strive to share our knowledge of coastal resilience planning to help you mitigate the risks of flooding. Contact us and learn how our digital, custom solutions can empower your decisions. Browse our solution: https://www.dhigroup.com/solutions/protect-marine-and-coastal-environments-with-nature-in-focus
