Blog 7 - When is a beach not a beach? When it’s a dune!
This blog looks at answering the simple question: what is a sand dune?
Nothing beats the beach
Nothing beats dropping everything and heading off for a day at the beach. Sun, sand, sea, ice-cream, a nice walk, a good book, the kids running free, a picnic, the list just goes on and on. While we think of it all as the beach, many of the things we do on these memorable days actually happen in the dunes. It’s nice to get out of the wind, get some privacy, have a picnic on the grass (less sand in the sandwiches), play hide and seek, walk up and down the sand hills. And it is the variety in the dunes that make them such appealing places.
Nothing beats the beach - Maybe the dunes do
In some places, dunes are known as sand hills, and this is probably the most intuitive description of what they are: places where sand has built up into small mounds (10s of centimetres high) or large hills (10s of metres high). They are often covered in plants, with marram grass quite common – that long one that jabs your legs. Dunes are built by wind. This means the sand is usually finer than on the beach (lovely an soft for bare feet). The individual grains of sand are smaller and easier for the wind to pick up and move. Compare that to the beach, which is made by waves. Waves are much stronger and can move larger grains of sand and even bigger ones like pebbles and cobbles.
CoastCare (NZ) "Meet the Dunes"
(lovely 5-min video)
So,
1) The waves move the sand from the seabed to the beach
2) The wind blows the finer sand up the beach
3) Plants slow the wind down and the sand is dropped
4) The sand builds up as mounds, hills and ridges – these are the DUNES
5) More plants grow, with their roots stabilising the dunes.
It is these dunes that offer us the shelter from the wind and diversity of shapes that make them ideal for exercise and recreation. It just so happens that diversity is also ideal for unique plants and animals to thrive too – this biodiversity creates wonderful habitats that are internationally valued as Special Areas of Conservation. Flowering plants, lizards, toads and ground-nesting birds all call the dunes their home. As large ridges the dunes also act as a barrier to coastal storms, protecting the land behind them (coastal protection for free).
Bull Island: The Heart of Wild Dublin
(this short film gives a great idea of the biodiversity of dunes)
Nothing beats the beach - Maybe the dunes do - Well, they do and they don’t
Well the case for dunes over the beach is pretty strong. BUT (there’s always a but), beaches and dunes are so popular that we put them under tremendous pressure. Where beaches can take a lot of coming
and going, dunes are much more fragile. The tough plants that bind dunes in place are actually not suited to being walked on. They are not like grass in your garden, or on a sports field – those grasses have been developed over time to withstand us using them over and over again. Dune grasses and plants, though, die back very quickly with human trampling. The sand is then free to be blown away, and what looks like ‘coastal erosion’ is actually human erosion!
Paths from over use of fragile dunes are
destabilising the dunes of Bertra, Co, Mayo
What can we do
1) In places where the dunes are narrow (10s of metres wide), ENJOY the beach and avoid using the dunes in any way – sorry it is that simple
2) In places where they are wider, stick to marked paths and respect local signage on how to use them
3) Where erosion is a problem, help out (or form) a local action group. Dune planting, sand-fencing, involving many local groups & managing authorities, and awareness amongst users are the basics of ‘working with natural processes’ for restoration (this will only work where sand is naturally available).
Sand Dunes in 3 words
Hills : Wind : Plants
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