{"id":2367,"date":"2023-05-02T13:31:35","date_gmt":"2023-05-02T13:31:35","guid":{"rendered":"https:\/\/horizon.peachpuff-wolverine-566518.hostingersite.com\/?p=2367"},"modified":"2023-05-02T13:31:35","modified_gmt":"2023-05-02T13:31:35","slug":"sand-dunes-offer-clues-to-coastal-erosion-and-how-to-prevent-it","status":"publish","type":"post","link":"https:\/\/scienceblog.com\/horizon\/2367\/sand-dunes-offer-clues-to-coastal-erosion-and-how-to-prevent-it\/","title":{"rendered":"Sand dunes offer clues to coastal erosion and how to prevent it"},"content":{"rendered":"

The management of these natural barriers through the ages could hold lessons for coping with climate change and rising sea levels today.<\/p>\n

By<\/em><\/strong>\u00a0\u00a0SOFIA STRODT<\/p>\n

The 200 million Europeans who live in coastal zones are already feeling the impact of global warming through extreme variations in sea level and flooding.<\/p>\n

Many parts of Europe could suffer 10 times more coastal flooding by 2100,\u00a0depending on the trajectory of greenhouse-gas emissions that cause climate change,\u00a0according to the\u00a0European Environment Agency<\/a>.<\/p>\n

History lessons<\/strong><\/p>\n

\u2018For major cities close to the shore, this is going to be a big issue,\u2019 said Dr Joana Freitas, an environmental historian at the University of Lisbon in Portugal.<\/p>\n

The predicted rise in sea levels has focused attention on the measures that can be taken to protect Europe\u2019s coastline. As the first natural line of defence against flooding and coastal erosion, sand dunes have an important role to play in sheltering these areas.<\/p>\n

But today\u2019s sand dunes don\u2019t provide as much protection as they once did.<\/p>\n

Looking at how people have interacted with nature can provide valuable insights into recent changes in the environment and humankind\u2019s role in causing them, according to Freitas.<\/p>\n

She is the lead researcher of the EU-funded\u00a0DUNES<\/a>\u00a0project, which is putting together a complete history of human-environment interactions in coastal areas worldwide.<\/p>\n

The project, which began in November 2018 and runs through April 2024, covers France, Portugal, the UK, Brazil, Mozambique, North America and New Zealand.<\/p>\n

\u2018Humans have a long history of connecting with dunes,\u2019 said Freitas.<\/p>\n

That history is marked by ups and downs. In the 17th<\/sup>\u00a0to 18th<\/sup>\u00a0centuries, dunes in Denmark, France, the Netherlands and Portugal were considered dangerous because the sand blown inland by the wind silted rivers and harmed farms.<\/p>\n

Tree traps<\/strong><\/p>\n

To prevent this, coastal inhabitants planted marram grass\u00a0\u2013\u00a0Ammophila arenaria \u2013 to trap the sands.<\/p>\n

Later, from the end of the 18th century, several countries in Europe supported the planting of trees on dunes to prevent the destruction of arable land and increase dunes\u2019 economic value by turning them into forested areas.<\/p>\n

Trees can grow well on stabilised dunes and become part of their ecosystem. And, in general, vegetation such as grasses, shrubs and bushes can help stabilise dunes and prevent their erosion as well as provide a home for plants and wildlife.<\/p>\n

But large-scale tree plantings carried out in the 19th<\/sup>\u00a0century and early 20th<\/sup>\u00a0century caused more damage than the inhabitants likely realised. For one, as these new forests often were monocultures of non-native species, they disrupted the existing ecosystems.<\/p>\n

Second, extensive tree planting \u2013 along with the spread of urban areas, building of harbours and dams, dredging of navigation channels and construction of seawalls and low barriers known as groynes \u2013 caused profound changes in coastal areas.<\/p>\n

For example, they deeply affected the balance between sediment added to and removed from a coastal system\u2019s littoral zone, which is the part of a sea close to the shore. This activity reduced the amount of sand on some beaches, limiting their ability to act as a buffer and protect structures and buildings on the coast.<\/p>\n

Wave power<\/strong><\/p>\n

\u2018Dunes are keepers of sand, they are reservoirs,\u2019 said Freitas. \u2018When there are bigger and stronger waves during storms, the sand is taken from the beach, which creates an underwater barrier, so the next waves will be blocked.\u2019<\/p>\n

Eventually, over weeks or months, more gentle waves gradually return the eroded sand from offshore to the beach. This fluctuating of the shoreline backwards and forwards over time\u00a0<\/strong>is a normal coastal process that is hardly noticeable in normal times but can be dramatic during storms.<\/p>\n

Freitas is concerned that if the natural balance isn\u2019t maintained, beaches will eventually be destroyed and the coastal protection dunes provide will be lost.<\/p>\n

Olivier Burvingt, a researcher at the University of Bordeaux in France, is well aware of the potential impact of storms and sea level rises on coastal sand dunes.<\/p>\n

As part of the EU-funded\u00a0ERoDES<\/a>\u00a0project, Burvingt and colleagues are seeking to understand how dunes respond to and recover from extreme weather events along the Atlantic coast of Europe. The three-year project runs through August 2024.<\/p>\n

By using light detection and ranging, or LiDAR, laser technology, the ERoDES team can collect precise data from the air along several kilometres of dunes.<\/p>\n

\u2018Regional coastal monitoring programmes across Europe provide us with data that were collected using aircraft that fly over dunes,\u2019 said Burvingt. \u2018That way we can measure and study the topographical changes of the dune sediments with a vertical precision of up to 10 centimetres.\u2019<\/p>\n

Like Freitas and her team, ERoDES is also looking back in time and drawing on physical and digital archives and models to understand more about dunes\u2019 behaviour now and in the future.<\/p>\n

Regional puzzles<\/strong><\/p>\n

The vast amount of data collected by the project can provide insights into the difference in resilience of some of the most exposed coastal dunes along the Atlantic coast.<\/p>\n

For example, the team is studying the response and recovery rates of eight coastal dune areas ranging from north-western England to southwestern France in the 2011-2020 period.<\/p>\n

All the areas under study have been exposed to and eroded by massive storms in the Atlantic, particularly extreme weather experienced in the winter of 2013-2014.<\/p>\n

A puzzling element for the researchers is that, although exposed to the same storms, the dunes have responded differently and have all recovered at varying speeds. While some areas have returned to the same state they were in before the storms, others are still recovering or have lost even more sand.<\/p>\n

\u2018We\u2019re trying to understand why their response is different,\u2019 said Burvingt.<\/p>\n

All eight sites have different environmental characteristics, including tides, climate, dune size, coastline shape and vegetation density.<\/p>\n

One of the main findings from the project so far is that the dunes with the steepest slopes were the ones to lose the most sand.<\/p>\n

Another is that the rate of recovery is mainly dependent on the amount of sediment available along the coastline. Being able accurately to assess these sediment budgets is key to anticipating the evolution of coastal dunes.<\/p>\n

At the project\u2019s end, these results will be shared with coastal authorities across Europe. Based on the characteristics of each region, officials can tailor a strategy to protect the dunes, restore the coasts and guard against future storms and flooding.<\/p>\n

New approach<\/strong><\/p>\n

Both ERoDES and DUNES advance a broad\u00a0EU initiative<\/a>\u00a0to help cities and local authorities better understand the climate threat they face and how to react in time.<\/p>\n

But in doing so, the two projects take a new approach to adapting to global warming by avoiding a traditional focus on new technologies and methods that can prevent, or at least reduce, the impact of future flooding, drought, wildfires and other consequences of rising temperatures.<\/p>\n

Instead, ERoDES and DUNES move towards relying on steps that work with an ecosystem rather than introducing traditional human-made fixes such as seawalls, dams and dikes. Future dune restoration and protection are set to depend on planting native vegetation and re-introducing indigenous plant species\u00a0\u2013 actions that are kinder on the environment and relatively inexpensive.<\/p>\n

\u2018This simple and effective\u00a0nature-based solution<\/a>\u00a0has been done by coastal populations for centuries in some European countries,\u2019 said Freitas.<\/p>\n

As for the research itself, she stressed the benefits of its interdisciplinary nature.<\/p>\n

\u2018One of the most important contributions of DUNES is to show that transdisciplinary work between the humanities and the sciences is possible, rich and valuable and should be a path to follow more often in the future,\u2019 Freitas said.<\/p>\n

ADAPTING TO CLIMATE CHANGE<\/strong><\/p>\n

According to the latest data from the\u00a0World Meteorological Organization<\/a>, Europe is warming twice as fast as the world average.<\/p>\n

Adapting to climate change means taking action now to prepare for both the current effects of climate change and the future ones.<\/p>\n

The\u00a0EU Mission on Adaptation to Climate Change<\/a>\u00a0focuses on supporting EU regions, cities and local authorities in their efforts to build resilience to the inevitable effects of a changing climate.<\/p>\n

With concrete targets for 2030, the\u00a0EU Mission to Restore our Ocean and Waters<\/a>\u00a0will protect and restore aquatic ecosystems to support biodiversity and ensure native wildlife and plants have a home for years to come.<\/p>\n

Nature-based solutions<\/a>\u00a0are inspired by and supported by nature. They use nature\u2019s own resources – clean air, water and soil – in a smart way, to tackle environmental challenges while supporting biodiversity and providing environmental, social and economic benefits.<\/p>\n

Other EU-funded projects that are implementing nature-based solutions to coastal erosion, including dune restoration, include\u00a0REST-COAST<\/a>\u00a0and\u00a0Interreg MANABAS<\/a>.<\/p>\n

More info<\/p>\n