Software could help prevent disaster in sinking cities

A Nottingham University researcher has been awarded funding to help China prevent human disaster as some of its fastest-growing cities sink under the weight of towering skyscrapers.

Dr Andrew Sowter, a mathematician and scientist at the University of Nottingham Ningbo, China (UNNC), is developing a computer program that will help Chinese authorities identify with greater accuracy exactly where, and by how much, structures are moving.

The UNNC scientist’s software will analyse satellite images gathered over several years to reveal how much land has moved, in millimetres, across the entire city.

The National Natural Science Foundation of China − affiliated to China’s highest governing body, the State Council − has granted funding of about ¥500,000 (about £50,000) for research that will use Shanghai as a case study.

Shanghai, like several other coastal cities in China, is built on marshy soil, making it vulnerable to sinking. One of the most densely populated cities in the world, it is believed to be sinking at an average rate of 2-4cm a year, putting pressure on underground pedestrian and railway tunnels, and building foundations.

In 2003, subsidence was blamed for the collapse of an eight-storey building in Shanghai’s inner-city Bund region, which is known for its iconic commercial real estate.

The pumping of groundwater to cater for a massive, growing population has been a significant contributor to subsidence. The problem has been exacerbated by the country’s decades-long building boom amid rapid urbanisation, said Sowter.

Sowter is working in collaboration with Shanghai’s Tongji University, which is gathering ground information to confirm the results of data gathered from space.

’We are advancing and refining existing computer programs so that we can identify risks with greater confidence of the accuracy of the results. Rather than just measuring the problem, we are also improving the models to map and identify priority areas,’ he said.

The Nottingham Ningbo scientist has also commenced research on the coastal city of Ningbo to assess the extent to which it might be sinking. An underground rail system is being constructed to accommodate the estimated eight-million-plus population of greater Ningbo, which, like Shanghai, has developed rapidly and is on water-logged land.

Sowter said that the technology he is developing can be applied to other risks associated with land, such as earthquake zones, high-risk flood areas, land deformation from mining, and glacier movements. It can, for example, help authorities prevent landslides by detecting where land is starting to move at the stage when changes are slight.