Protecting coasts from coastal erosion - Two solutions

The Coastal erosion is a problem that affects our coasts and beaches: to counteract the phenomenon, the USA and the Netherlands have developed innovative systems to combat the incessant action of the sea and protect the coasts.

Coastal erosion - Rough seas hit the coast at Brough Head, 10 miles south of John O' Groats on the north-east coast of Scotland. — Coastal erosion north coast Scotland | Image source: Envato Elements

Coastal erosion is a major problem in Italy, as the country has 7500 km of coastline. The tides and currents remove material from the coast every day, requiring costly and non-permanent replenishment measures (the addition of sand to the seabed): in Emilia-Romagna alone, 19 million euros were invested in 2022 to maintain just 11 km of coastline, moving 1.5 million m³ of sand. Other possible measures include the use of breakwaters, often made of concrete or large rocks, which can reduce the force of the waves that hit the coast.

Protecting coasts from coastal erosion is therefore an important issue. The sea can threaten not only tourist beaches, but also inhabited areas, as in the case of the North Cove region (USA) or extensive lowland areas such as the Dutch coasts. Both communities have looked for alternative solutions to simple replenishment and are therefore interesting examples.

One man against the Pacific: How David Cottrell saved Washaway Beach

The area of North Cove, a rural community in Washington State, is also known as "Washaway Beach" because of the severe coastal erosion caused by winter storms and the tides of the Pacific Ocean.

In the past, the sea has reclaimed up to 30 meters of shoreline per year due to human intervention such as the construction of a dam on the Columbia River, which has reduced the amount of sediment being transported to shore, destroying homes and other buildings such as a lighthouse and part of a Coast Guard base.

One of the houses that recently collapsed into the Pacific Ocean at Washaway Beach in Washington State. — Coastal erosion Washaway beach | Image source: Wikimedia Commons

Due to the low economic importance of the mainly agricultural and sparsely populated area, the federal authorities have shown little commitment in the fight against the Pacific in recent decades, avoiding costly infrastructure and often leaving the initiative to private individuals.

David Cottrell, a North Cove born and raised farmer with a background in math, founded an organization called WECAN (Willapa Erosion Control Action Now) in 2016 with the help of his wife Connie Allen, which now includes local institutions, citizens and even the descendants of the Shoalwater Bay tribe.

Cottrell's idea was to create "artificial mounds" of basalt pebbles in the coastal areas most affected by the tides, a system that has been used for centuries for shellfish farming and fishing: These structures can reduce the force of the waves hitting the beaches while retaining the sand, restoring the dunes that are normally washed away by the currents.

The project has shown promising developments over the years, which are monitored by the Washington State Department of Ecology: Despite an initial major investment, the structures appear to withstand weather conditions and can be maintained by citizens themselves at little cost, with flows monitored each season and improvements made where needed.

Sadly, Cottrell will not live to see the future developments of his project: He passed away in June 2023 after a cycling accident.

Zandmotor, the Dutch project to protect the Delfland coast

In the Netherlands, due to the particular geography and the large areas of "stolen" land below sea level, coastal protection is a much more pressing issue. One of the projects funded by Rijkswaterstaat, the Ministry of Infrastructure and Water Management, is the so-called Zandmotor ("sand motor") on the Delfland coast.

In 2011, a huge amount of sand dredged offshore was deposited above the beaches to be protected, creating a hook-shaped peninsula. The idea behind this project is to create a deposit, with an amount of sediment equivalent to 20 annual replenishments, in a position that will allow the currents and winds to distribute the sand over the years while protecting the coast from the waves of the North Sea.

Zandmotor, The Sand Motor in The Hague — The lagoon created by the Zandmotor has quickly become a tourist attraction, especially for local kitesurfers. | Image source: Denhaag.com

The peninsula extends 1 km into the open sea and about 2 km along the coast, with a maximum height of 5 meters above sea level. Within the peninsula, a small lake ensures the normal drainage of groundwater, which would otherwise be impaired by the structure.

An initial study completed in 2016 showed the effectiveness in protecting the coast from erosion or flooding and creating a new habitat for the local flora in the lagoon created behind the dunes.

The potential dangers to bathing have been monitored over the years, given the changes in sea currents near the peninsula, and sand deposits have been noted both north and south of the structure.

The original estimate of 20 years would already justify the large investment of 70 million euros, which is much higher than for normal replenishment measures; however, the presence of 95 % of sand five years after the initial work suggests that the intervention could last even longer.