In my last article we analysed the conditions and estate of coastal sand dunes in Spain and discovered that the sand dunes have been mistreated during a long time, nevertheless the Spanish authorities have realized now of their importance and are trying to do something to improve the situation because they have discovered a simple fact; without dunes beaches will disappear.
How do we save the sand dunes?
In the Spanish case, professors from the Autonomous University of Madrid propose that the central and regional governments reach agreements for a comprehensive protection battle on both the state public domain, and the area surrounding the dune ridges.
This week we will focus on those actions carried out to save the Spanish coastal dune.
How do coastal sand dunes form?
Dunes are formed when wind and waves transport sand onto the beach. The first source of the sand is often from a glacial region till it arrives onshore, or is eroded from nearby cliffs by waves and transported along the shoreline by long shore currents. Rivers can also transport sand to the coast from inland deposits. Waves wash this sand up on the beach, but can also remove it during storms. One beach can vary quite substantially with the seasons. During the winter, stronger waves pick up more sand, causing the beach to be steeper and coarser. In summer, gentle waves transport sand onshore and the beach takes on a shallower slope with finer sand.
Gone with the wind…
Once sand has been deposited on a beach, it is transported by the wind. When the prevailing wind direction is onshore, the sand gradually migrates landward from the water’s edge. Shallow slopes of sand from grains move up the slope and are dropped on the steeper lee side of the pile, where the wind velocity is lower. When plants colonize dunes, their roots and stems help to anchor the shifting sand. The structure of plant stems and leaves create small pockets of protection from the wind, causing more sand to accumulate. It is important to note that sand dunes undergo a continual cycle of erosion (breaking down) and accretion (building up) with the wind and waves. When structures are built so close to a beach as to prevent this natural fluctuation, overall erosion of the beach and loss of dunes can occur. This leaves a shoreline much more vulnerable to damage from storms.
What can do you to help?
Obviously no one will ask you to undertake such endeavour and although anyone could find out certain strategies to preserve coastal sand dunes it is always better to leave those decisions to the experts in case we think we are improving the situation and we are really deteriorating it without knowing it.
I have seen in Ibiza governmental attempt to improve large parts of coastal dunes by planting grass, not any type of grass, but the variety Ammophila Breviligulata which is the most effective plant to stabilize existing dunes and can help to build new dunes along the coastline. This vegetation is easy to plant and it spreads rapidly. It reduces wind velocity near the ground and traps windblown sand around the grass. As the sand deposits accumulate, the grass grows up through it maintaining a protective cover.
Another method they use to help to stabilize the dunes is building sand-fencing.
Sand fencing erected at the base of the dune and along walkways helps to keep people from walking on the beach-grass. Sand fence is also effective in trapping windblown sand.
The sand fencing I saw was erected at the base of the dune on both the seaward and landward sides to block access and was secured to the posts using wire or staples. These are major projects but we all can help by:
Not throwing rubbish, tires or other debris on the dunes.
We have learned that dead trees and dead bushes are fire hazards that can lead to the destruction of established dunes.
Any fire onto the beach grass destroys its ability to trap sand and may kill the plant. Other debris such as car parts, concrete, cinderblocks, wire, tires, patio pavers, bricks is not effective materials for dune building. They do not degrade and are hazardous to people sunbathing on the beach.
Keep boats off of the dunes: In some coastal towns it is common practice for property owners to drag their boats over the dune or to store their boats on top of the dune. It is important to remember, the dune provides protection for you and your neighbours. The vegetation will eventually be killed in the area where you drag or store your boat. Once the vegetation is gone this area becomes vulnerable to wind erosion.
But more important of all….Tell others about sand dunes: If you aren’t a good environmental representative, who will be? Tell others about the importance of protecting sand dunes and the coastal environment.