Is it worth it?

When monsoon rains hit the Indian megacity of Mumbai, 171 small businesses in the Ansa Industrial Estate on the outskirts of the city risk production stoppages due to flooding.

Indian engineers have examined the problem and proposed solutions such as establishment of pumps, wells, and new drainage systems. But is it worthwhile for small business owners to invest in the proposed climate protection? What benefits will they reap—and will the benefits outweigh the costs? Professor Kirsten Halsnæs and Postdoc Per Skougaard Kaspersen can help them answer this question by means of a digital calculation tool developed by the two researchers from DTU Management Engineering.

“It’s a cost-benefit tool that can help with cost estimates. What does it cost to repair damage after a flood? What does it cost to avoid the problems? And what is the economic value of reducing the damage?”, says Kirsten Halsnæs about the tool, which also contains climate projections to take into account the more frequent and heavier downpours of the future.

Dynamic costs of damage

The costs of preventing flooding are relatively easy to calculate—they are the costs connected with the establishment of wells, drains, and pumps. Calculating the benefits is slightly more difficult.

“There are a lot of consequences of flooding that are difficult to measure. What is the economic cost of people becoming ill as a result of flooded sewers, or of them being unable to get to work because the roads are flooded? And how will the costs of damage develop in line with the implementation of climate change adaptation? For these measures will—of course—change the risk of damage,” says Kirsten Halsnæs, and she continues:

“We’ve therefore invented a new concept which we call dynamic costs of damage?. Estimates of costs of damage have so far been based on very static models. But we take into account that the costs of damage develop over time because society also develops: New technologies will become available and more climate change adaptation will be implemented, and citizens also learn from events and begin to react to them.”

DTU has developed a cost-benefit tool in connection with consultancy on floodings in Mumbai. But it can also be used in all other towns and cities. Photo: Per Skougaard Kaspersen.

Is to improve Danish coastal protection

The calculation tool from the Mumbai example will play a central role in a large Danish coastal protection project, in which DTU is to help strengthen coastal protection measures. Kirsten Halsnæs is heading the project.

Denmark has a coastline of 8,750 km, and more than one million people live near the coasts.

Climate change is causing rising sea levels and more frequent storms, which reinforces the problems of flooding along the coasts. The new project covers the full range from technical and natural scientific mapping of coastal floodings to damage and loss assessment, social initiatives, warning systems, and technologies. The project is to result in new models and a digital platform for coastal protection and emergency response.

One of the tasks for the DTU researchers is to link calculations to cost-benefit analyses which also take into account local challenges, where the water comes not only from the sky, but may also rise up from rivers, fjords, or flow in from the Baltic Sea.

Challenged by both precipitation and fjord

The latter is precisely the case for the town of Aabenraa in Southern Jutland, located at the base of Aabenraa Fjord. As a result of this location, the town is challenged when heavy winds and a depression with storm from the west push water from the Skagerrak into the Baltic Sea Once the storm releases its grip, the water 'ripples' back, causing sharply rising water levels in, for example, Aabenraa Fjord. If there has been concurrent heavy precipitation over land, streams and rivers around Aabenraa cannot get rid of the rainwater due to the high water level in the fjord. When these events occur concurrently, Aabenraa thus experiences flooding of both the low-lying areas of the town and outside the town, e.g. allotment gardens, which are flooded by streams and brooks that overflow their banks.

Stig Werner Isaksen, Administrative Director of Culture, Environment and Business in the Municipality of Aabenraa, hopes that the coastal protection project will bring the municipality a step forward in the planning of climate change adaptation measures.

“We hope to be better equipped to decide what is the right thing to do: How do we best develop our town, and what emergency responses must we have in place to provide the best possible prevention of floodings and avoid flood damage? We hope that the project will pinpoint various options for action, so that we’re as well prepared as possible,” says Stig Werner Isaksen and continues, “After all, it’s about both the measures that our citizens take on their own property to avoid major flood damage, and how they can become part of coordinated initiatives in the emergency response work to prevent flooding.”

Climate change adaptation is about more than technology

Mobilization of the civilian population is precisely an interesting dimension of the coastal protection project, finds Kirsten Halsnæs.

“Climate change adaptation is about more than technology. There’s also a human aspect. It’s about getting citizens out of the role of victims, so that they don’t just climb up onto their roofs or leave town when extreme weather hits their area. Adapting to climate change is also a question of giving citizens some options for taking action,” she says.

DTU has developed a cost-benefit tool in connection with consultancy on floodings in Mumbai. But it can also be used in all other towns and cities.