Cowi has announced that new research published in Risk Analysis journal has created tools to mitigate the risk of groundwater drawdown induced subsidence.
According to Cowi, the new study - Risk mapping of groundwater-drawdown-induced land subsidence in heterogeneous soils on large areas - provides an innovative mapping method to reduce the risks. The study is based on the use of probability-based models.
“We looked into areas where there is a risk of subsidence, if you lower the groundwater level,” said Cowi hydrogeology engineer Jonas Sundell, who is also an industrial PhD student at Chalmers University of Technology in Sweden.
“These issues used to be addressed in a rather fragmented way; the geotechnical engineers drilled holes in certain places and the hydrologists examined other areas, but they could never tie the information together effectively. With the new method, they can do this. The method is probability-based and describes where in an area the risks may be found.”
Sundell used the City Link high voltage utility tunnel in Stockholm, Sweden as a case study for his PhD. He said it demonstrates the efficiency and usefulness of this modelling approach as a tool for communication to stakeholders, decision support for prioritisation of risk-reducing measures and identification of the need for further investigations and monitoring. The method has also been used on the Stockholm Bypass and the West Link in Gothenburg.
“In this study, we looked at 20,000 boreholes in central Stockholm. Some were for the electric cable tunnel covered by the case-study, and others for projects that we found in the city archive and with relevant authorities,” said Sundell.