December 22, 2025

expert reaction to the Shropshire canal sinkhole

Scientists comment on a canal sinkhole at a canal in Shropshire. 

Dr Michael Branney, Emeritus Professor of Volcanology, University of Leicester, said:

“From the drone & media footage, the canal burst at Whitchurch in Cheshire last night seems to have been a canal embankment collapse rather than a sinkhole.

“Sinkholes are natural subsidence structures that form when soluble bedrocks, such as limestone, gypsum or rock salt beneath the ground, are gradually dissolved over time by slightly acidic rain and groundwater, forming an underground cavity that gradually gets larger with time. Eventually the unsupported cavity roof collapses, and a large sinkhole appears in the ground, often unexpectedly. Sinkholes are typically associated with regions of karst (limestone) or evaporites (rock salt).

“From the media images of last night’s event (note: I haven’t visited the site) it appears that the canal at Whitchurch locally lies upon a man-made raised embankment, and it is this bank that has catastrophically collapsed, with water draining down into a neighbouring field. The bank, which includes the base of the former canal, locally lies at a higher elevation than adjacent ground, and appears to have been built of rocks, soil and clay, and it is this structure that has collapsed. The event then, was probably a canal embankment collapse rather than sinkhole subsidence, and it was probably caused by high water levels this winter. There are various possible causes of bank collapses causing canal breaches. Water that has penetrated into earthworks can destabilise them over time, particularly when the water pressure is elevated.

“Typically, specialist site investigators (geotechnical engineers) could, in the near future investigate the cause of this bank collapse, with a view to assessing possible further occurrences and repair. Other canal embankment collapses have occurred in recent years, such as on the Bridgewater canal in Cheshire.”

Dr Martin Stokes, Associate Professor in Geological Sciences at the University of Plymouth, said:

“Sinkholes occur where the ground surface collapses, and this process can be slow or extremely rapid. They can occur in natural materials such as soil or rock, or in human made earthworks, and typically the collapse involves water getting within the pore spaces found in between soil particles or within fractures within the rock mass. The collapse can occur for a number of reasons such as when water is removed, when water begins to flow because the soil/rock pore spaces become saturated, or when soluble soil/rock material with carbonate or salt content becomes dissolved.

“It’s not wholly true to say they are unpredictable, as in some locations sinkholes are in fact very predictable (for example, in limestone areas where cave formation via dissolution occurs). Florida in the USA is a great example of these naturally occurring karstic sinkholes, but in the UK, sinkholes tend to be unpredictable because they occur suddenly in places where they have not occurred before. Sinkholes are increasingly being reported in built environments, and roads can collapse or subside due to sinkholes opening up because the road base material is washed away, either by excess rainfall or by a burst water main. Surfaces can also collapse due to the opening up of a mine shaft.

“They can be very dangerous for vehicles, people or even buildings as there is the risk of them collapsing directly into the hole as it opens (or driving/walking into them if they are not seen in time). The Shropshire example looks like the collapse of a human made earthworks embankment along the canal edge.”

Dr Jonathan Paul, Associate Professor in Earth Science, Royal Holloway, University of London, said:

“Sinkholes form where water percolates through permeable and soluble rock like limestone, slowly dissolving it. Over time, large cavities in the sub-surface may be created, which might eventually cave in to form the sinkhole. 

In some cases, so-called “sinkholes” results from intense underground flooding from burst water mains. 

It is very tough to predict to a reasonable degree of accuracy where and when sinkholes might form. This is because the flow of water through the ground is very poorly constrained, as well as the strength, porosity, and permeability (i.e. degree of fracturing) of the rock layers through which the water flows.”

Declared interests

Dr Martin Stokes:  “The only past relevant role I have had is a co-editor in chief of the journal geomorphology where I had experience in editorial handling of natural sinkhole papers from overseas”

Dr Jonathan Paul: “No COIs”