Coast protection alternatives
We need to protect our coasts from global warming and – because of that – the sea level rising. But should we only use concrete seawalls?
Why not use nature against nature. Or a combination with classic engineering?
It’s a beautiful, natural coastal protection and soften shoreline defenses are multifunctional. It’s attractive to all kind of sea lives, tourism, fisherman and therefore a whole industry behind. Let’s have a look at alternatives.
But … If there are areas that are critical to defend, then walls and bulkheads are probably still the best way to do it.
Protection from nature
Living shorelines – or protecting the coast with nature – are typically sloping barriers that mimic natural shorelines. They are planted with vegetation and salt marsh to help make them strong. They buffer, but they also move and change as any undeveloped shoreline would.
- Living shorelines and vegetated dunes are designed to soften water impact by providing a slope the water can run up to dissipate its force.
- They leave habitat in place for animals and plants.
- Salt marshes stay in place to do their work.
- And as long as there’s no other blocking infrastructure, like a road, they let all of the above move and shift as needed.
1. Oyster reefs and marshes for Alabama
The Alabama Nature Conservancy is promoting a stair-steps cage system – a series of cages that step down from a bulkhead. Marsh plants grow up through the cage slats, creating a slope that helps dissipate the wave action against the bulkhead.
The coast has been eroded badly:
- the Gandy’s Beach shoreline has shrunk by nearly 500 feet since 1930.
- Superstorm Sandy hit the region’s coastal ecosystems hard in 2012, further diminishing their protective value and leaving the communities vulnerable to significant flooding.
Protection comes from the installed oyster breakwater structures. This will help nto reduce local erosion problems and provide quality habitat for species like horseshoe crabs and red knots. The reef was constructed from a combination of materials, including:
- oyster castles (stackable, interlocking blocks of concrete, limestone, crushed shell and silica that encourage oyster larvae to settle, as well as bagged oyster shells collected as part of a shell recycling program
- 7,500 bags, which serve as building blocks for the breakwater along with the oyster castles.
- coconut fiber within an exterior of coir (husk of coconuts) mesh netting that holds everything together.
The Alabama Nature Conservancy has done similar coastal restoration projects in the Gulf of Mexico. The results showed a reduction in wave energy and erosion, helping reduce flooding, and also an increasing wildlife habitat.
2. A sandy wall protection in Colombia
A ‘sandy wall’ in front of the coast of Colombia protects the coastline between the mouth of the Río Magdalena river and the town of Ciénaga. By sand replenishment and especially natural forces such as wind and sea to do her job, a natural buffer in turn may arise.
The Colombian Ruta Nacional 90 threatens to disappear into the sea because of the erosion. To date, especially hard constructions taken as a measure against erosion. This often proved very costly, ineffective and durable.
3. The SandMotor protects the coast of the Netherlands
In 2011, Dutch engineers created the hook-shaped peninsula. It extends 1 km into the sea and is 2 km wide where it joins the shore.
Trailing suction hopper dredgers picked up the sand ten kilometers off the coast and took it to the right place. Two offshore replenishment locations alongside the peninsula are also part of the SandMotor. The SandMotor project can be regarded as a ‘field laboratory’ of physical and institutional learning and an innovation for mainstream flood protection. Read more
4. Natural dams protect the coast of Indonesia
Indonesian inhabitants dragged prunings to build dams and protect the coast line against erosions.. Each dam is about 100 meters and increases the land with already 20 centimeters (almost 10 inches) of new coast. The coastal protection is called ‘building with nature’. Read more
- Coastal erosion stopped by using geo-textile bags filled with solid sediment
- Florida’s fears of further beach erosion and coastal flooding
- Delta city Jakarta protected by Dutch Water Experts
- Dozens of America’s east coast cities face routine tidal flooding under climate change
- Computer models can help coastal managers making better decisions
- Coast Indonesia protected by ‘building with nature’
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