The sand dunes at Crantock Beach have been in the news over recent weeks, as shifting sands and high tides have caused the large sand dunes to the rear of Crantock Beach to become over steepened. The RNLI and Crantock Beach have issued warnings in the national media about the dangers posed to beach users, of the risk of collapse and possible engulfment.
Crantock is a popular beach, located to the west and southwest of Newquay, between east and west Pentire Point. Crantock is popular with families, in part because of the Gannel River which discharges onto Crantock Beach, on a warm day the Gannel is perfect for SUPs and Crantock and the neighbouring Porth Joke Beaches are a couple of may favourite ocean swim spots.
However in the high season, the beach becomes busy and invariably the dunes will attract intrepid children looking for somewhere to climb, slide and of most concern… dig!
So what can make sand dunes so dangerous?
Sand dunes and blown sand (aeolian) systems are hugely dynamic. Dunes can migrate at a surprising rate under the influence of prevailing winds, and throughout history British Dune systems have recorded large scale movement, such as those at Culbin Sands, east of Inverness, which overwhelmed the Culbin Estate in 1695 and completely covered an area of rich cultivated land.
Where sands migrate to a point where they come into the intertidal zone, and contact is made with the waves and tides, then previously stable dunes systems can become excessively steep and prone to landslides and landslips.
The dunes themselves are formed by blown sands, the sand particles are typically dry and uncompacted, as the face of the dune becomes eroded, the angle of the dune exceeds the natural angle of repose (the steepest angle at which sand can remain stable), the sand grains lose cohesion and slide down as a landslide or landslip. Sand dunes may collapse under their own weight under certain circumstances, particularly where they have achieved significant height (15-20 metres) and where other external factors such as wind, rain or groundwater flow cause destabilisation and saturation.
These sudden landslides or landslips can bury or trap anything or anyone in their path. When a person or animal is caught in a steep sand dune collapse, there is a risk of suffocation or entrapment. The weight and force of the sand can make it extremely difficult to breathe or escape. Rapid burial in loose sand can quickly lead to asphyxiation.
Local emergency services including the RNLI, Coastguard and Fire and Rescue are well aware of the risk posed to beach users, by shifting sands and unstable dune systems. Co-ordinated drills are commonly undertaken with the rescue services to practice techniques to search for and rescue those who may become entrapped. Techniques have evolved in many cases from those used in the alps to rescue survivors of alpine avalanches, but specialist tools and techniques have also been developed for the collapsed beach dune scenario. The ‘Sand Lance’ is one such tool, which uses compressed air to clear the sand away from the victim and to alleviate the load imposed on the victim.
This method was successfully utilised to save the life of an 18 yo man trapped in a sand collapse on the adjacent beach at Fistral in July 2021.
So enjoy the beach, bring your families, play in the sea and on the beach, even dig some holes…within reason. But be aware of some of the dangers, and make sure you and your kids follow this advice:
Refer to our Blog page for more information on Slope Stability Assessment.
