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This story features in Unearthed: Water Security

This is a perspective piece written by Michaela Crum, Customer Solution Manager, Seequent.

Last year, Houghton, Michigan, where I went to University, experienced a 1,000-year storm event with 14 centimeters (5.5 inches) of rain falling in six hours. Massive flooding destroyed property and infrastructure. Roads I once lived on were ravaged by sinkholes and converted to rivers. The governor declared a state of disaster for the counties affected, and the total cost of damage to public infrastructure alone sits at approximately $100 million, not including the devastation to homes and businesses.

It made me think of what can be done to prevent such a disaster in the future. How can cities flood proof to become more resilient in an environment of growing urbanization and changing climate? That’s when I became interested in the concept of ‘Sponge Cities.’

How it works

A Sponge City is designed to absorb, clean, and reuse rainfall in a safe, ecological manner that reduces potential damage from flooding and pollution. Techniques include replacing concrete pavements with wetlands, permeable roads or new forms of porous asphalt; plus green rooftops and rain gardens.

By 2020 China hopes to turn 15 major cities into Sponge Cities with the ability to absorb and re-use at least 70% of rainwater. This, of course, comes with major challenges. Retrofitting existing infrastructure in cities is difficult and expensive – China’s program will cost hundreds of billions of dollars – so creating cities with sponge models from the start makes more sense, and leads to lower investment and maintenance costs.

By 2020 China hopes to turn 15 major cities into sponge cities

What it offers

The initial driver for Sponge Cities was flood proofing in urban areas, however, ‘spongy’ infrastructure is beneficial in many other ways. It allows cities to capture and store water for various uses and enhancing water supplies.

Water absorbed into the soil is naturally cleaned and purified, and stored as groundwater reducing the burden on sewer systems. This also helps clean polluted runoff creating a better quality of life. These green initiatives help Sponge Cities become more resilient, sustainable, and provide a holistic approach to water management for growing urban areas.

Geology’s role in Sponge Cities

Geology plays an important role in planning for Sponge Cities. The subsurface properties of soil are crucial to determining how well water will be absorbed and stored for future use. Properly modelling the soil can enable cities to plan ideal locations for water retention.

It would be hugely rewarding to use Leapfrog Works to model the geology and infrastructure for a Sponge City plan – especially when the terrible damage flooding can create has such a personal relevance for me. Being able to incorporate geology with the infrastructure models to view sewer networks, pipes, and water storage areas would be highly useful in this special corner of the Water Security story.


Michaela Crum
Customer Solutions Manager, Seequent