Our Beaches Are Shrinking!

Do you remember the fun of building sandcastles at the beach? It’s something almost every child loves to do, but perhaps not for too much longer. According to an article published in The New York Times last week, seventy-five to ninety percent of the world’s natural sand beaches are shrinking. According to Professor Gillis of Rutgers University, this is due to a combination of increased storm activity, rising sea levels and human development of the shoreline.

Landsat 8 Image of Chesapeake Bay from the 28th February 2014. Image courtesy of the U.S. Geological Survey.

Landsat 8 Image of Chesapeake Bay from the 28th February 2014.
Image courtesy of the U.S. Geological Survey.

The impact of storms was demonstrated last winter when millions of tonnes of sand were stripped from our shores. The beach at Formby in Liverpool lost thirteen metres of coastline, whilst in Cornwall Perranporth lost about a million tonnes of sand, Fistral Beach in Newquay lost thousands of tonnes of sand and the beach at Bude almost disappeared completely.

A snapshot of sediment movement can be seen in the Landsat 8 image above of the mouth of Chesapeake Bay in Maryland, USA. The Chesapeake Bay Bridge–Tunnel can be clearly seen stretching to the north, with a number of boats passing through it. The image is displayed as a pseudo-true colour composite, combining the red, green and blue wavelengths with some enhancements to bring out specific features. The suspended sediment around the coast can be seen in the complex colour patterns of turbulence and movement, and during storms this sediment will include the larger, and heavier, sand particles.

However, anyone who visited the seaside this summer might not have noticed the major loss of sand from last year’s storms. This is because beach replenishment is a major activity in many areas, either because the beach forms part of the protective barriers for the land or because the beach is tourist attraction. Sand is not an infinite resource, and most replenishment comes from other beaches, dredging or mining. For example, this year areas around Bridport and Lyme Regis in Dorset were reshaped with sand recovered from harbour dredging.

Beach replenishment is not the only usage of sand. Sand is the most consumed natural resource on earth, and the biggest user is the construction industry in the production of concrete. However, it is also used in any process that requires silicon dioxide which includes everything from wine to toothpaste, glass and computer microprocessor chips. In fact, according to The New York Times, the US sand and gravel business is fastest growing sector in their economy.

Sand is becoming scarce in the world. We need to start taking care of our sand, and think carefully about how we use it. Should we replenish every beach that loses its sand? If we don’t do start to take shrinking sand seriously, future generations of children may never experience the joy of building sandcastles on a beach.

The Question of Dredging

Dredging has been a hugely contentious issue in the UK ever since the St Jude’s storm hit the country on the 28 October 2013; this marked the beginning of a relentless winter weather pattern of heavy rainfall and high winds. This severe weather coupled with coastal surges breaching flood defences led to large parts of the UK to be under water – a situation that still exists for significant parts of Somerset. Satellite data was used to map the flooded areas as part of the flood response by UK government agencies; more details can be found in our post Is the Southern UK Flooding a Disaster?

As the flooding occurred local communities bemoaned the lack of river dredging in recent times, and they felt this was a significant contributing factor for the rising water levels. In Prime Minister’s Questions on the 29th January this year, David Cameron announced that once flood waters in Somerset had drained away, rivers in the county will be dredged. Dredging itself also creates problems, releasing suspended sediment into the river water and secondly the need to get rid of the dredged material.

Image of East Devon, UK taken by Landsat 8 on 4th November 2013.  The River Exe flows from top to bottom and the River Teign from left to right. Plumes of suspended sediment are clearly visible following periods of heavy rainfall in late October and early November 2013.  Image courtesy of the U.S. Geological Survey

Image of East Devon, UK taken by Landsat 8 on 4th November 2013.

The River Exe flows from top to bottom and the River Teign from left to right. Plumes of suspended sediment are clearly visible following periods of heavy rainfall in late October and early November 2013.

Image courtesy of the U.S. Geological Survey

In addition to flood mapping, satellite data can also be used to map and monitor sediment transported. The Landsat 8 image on the right shows the plumes of sediment visible around the east Devon coastline just one week after the St. Jude’s storm. Since 1972 the Landsat mission has continuously monitoring the Earth’s surface; and makes this information freely accessible for use across a range of sectors.

This week it was announced that dredging of the River Tamar, on the border between Devon and Cornwall, will continue for the next two years in order to keep the channels clear for access to Devonport Dockyard. The silt from this process will be deposited in Whitsand Bay, Cornwall, despite the area being designated as a Marine Conservation Zone.

Dredging is a tool coming back into the UK flood defence armoury; the benefits, and potential harm, will be monitored closely in the coming months and years.

Next week’s we’ll be looking at the accelerated coastal erosion from the winter storms.

Blog produced by Bryony Hanlon, work placement student with Pixalytics, and Andy Lavender.