The mature dunes contain a large amount of fresh water which is used for Amsterdam’s water supply. This tanker of water helps stop the fresh water supplies getting infiltrated by salt water from the North Sea.
Please see moisture graph.
Testing the moisture levels on the polders.
Secondly we tested the levels of pH at different stages of the sand dunes. We carried out the experiments with a pH tester. It is a meter with a metal pole coming out of it. You use it by prodding it into the sand and it measures the acid and alkaline level from one to fourteen, one being acidic and fourteen being alkaline. The meter then displays the result with its pin.
Before we carried out the pH level tests, we expected the sand to be alkaline near the sea, then to gradually get more acidic as we went further inland. We thought this because vegetation causes soil to be acidic and there is more vegetation away from the sea. But we were wrong with many aspects. The actual results show us that the sand is very alkaline by the sea and then neutral on the rest of the sites. Apart from the polders which were just slightly alkaline. We could not test the slacks and blowouts because we could not get close enough to them because of the barbed wire. Although I would expect the slacks to be more acidic, because of the vegetation, and the blowouts to be about neutral.
There were also some problems that we encountered with the pH tests as with other tests we carried out. The main drawback was that when we prodded the poles into the ground, there was no way of telling if we were too deep or too shallow. This stopped the experiments from being fair, since we may have gone different distances in each test.
As the graph shows, our expected levels of moisture were very different to our actual results. We thought that because of the high amount of vegetation on the mature dunes, there would be a high level of acid in the sand. The expectations proved wrong and the sand was actually a somewhat alkaline.
The amount of vegetation is an important factor regarding the sand dunes.
This effects the amount of wildlife that live around the sand dunes and how much strength the sand dunes have got. We found out how much vegetation was on the sand dunes by using a white grid, which had one hundred square gaps across it. We placed the grid down on the different sites, one to six and then counted how many squares had vegetation in it.
We thought that the amount of vegetation would rise from around zero by the sea to ninety-four – ninety-eight by the mature dunes. The expectations were correct. On the beach there was no vegetation whatsoever. This is because the sand is too fine and the wind is constantly blowing it away, hence not allowing any vegetation to make roots. On the fore dunes there is a lot more vegetation. This is because the sand dunes act as cover from the wind and rain. Some of the vegetation, which can be found on the fore dunes, include marram grass, which is a type of grass which needs only little food and water so they can survive easily. Other plants include goat willow, ribwort plantain and lesser hawksbit. The mature dunes are filled with hundreds of variety of vegetation. Still one of the main types is marram grass. Some of the trees include oak, sycamore, pine and maple. Another main point is that you can not see any sand because the ground is so well covered. There is so much vegetation around the mature dunes because it has had so long to grow and it has access to fresh water (see photo of mature dune).
Vegetation on the beach does not exist because of the amount of erosion taking place. The vegetation on the fore dunes consists mainly of sea couch grass, which is tall and thin with sharp blades and a very short ligule. Sow thistle has spines to help it survive in the arid conditions on the sea front. Marram grass, sea spurge and sand sedge which has curly ends which give it extra strength in the sand. The areas of land near the slacks and blowouts have other types of plants helping it to survive. These include goat willow, ribwort plantain, lesser hawksbit dandelion and the common dandelion.
We discovered, in Holland, that humans have great impact upon how the sand dunes survive, both constructive and destructive. There are a lot of human activities going on around the sand dunes. Some, if not dealt with properly, could cause the sand dunes to wear down. Leisure activities include walking, cycling, horse riding and dog walking. Or just generally playing or sunbathing on the beach. Because there is so much human activity, the local authority has made a network of barbed wire and footpaths. They have been put up all over the vicinity to secure the future of the sand dunes. These will persuade people to stick to the footpaths and not wonder onto the top of the dunes. If people or animals were allowed to walk freely on top of the sand dunes, then the vegetation would suffer and that would make wind erosion more of a threat.
There have also been several buildings put up on the beach. There was a lifeguard station, somewhere to store sun beds and lots of litter bins (see photo of human influences. The sand dunes were purposely built there to stop the water from the sea, flood Holland out and put in under sea level. There is another reason why they have been put there. They hold the water that supplies the hole of Amsterdam. They act as a block so that the seawater can not creep into the fresh water. There was a lot of visual pollution on the beach and between the sand dunes; most of it litter from people who have been there.
If there were no signs or barbed wire putting people off travelling up the sand dunes then they would eventually be fully eroded. This is necessary so that Holland does not flood, but I do not think that it fits in very well with the sand dune environment. The sand dunes would be more attractive to look at without all of the barbed wire and organised footpaths.
The sand dunes are both conserved and preserved. The sand dunes have been conserved by making it possible for people to visit the area but making sure no damage can come to the sand dunes in the process.
Conservation is insuring environment is maintained for ever, but allow for some human activity to take place. The council have done this by constructing barbed wire fences around the actual sand dunes and only allowing the public to use the footpaths provided. They have also used the honey pot technique. This means that they have attracted the public to one side of the beach, where the litter bins, deck chairs, life guard and other facilities including a restaurant are. Then the other side of the beach, can be safely maintained and preserved. It is like sacrificing one part of the beach to save the rest of it.
Preservation is insuring that human activity can not change it at all. At Noordvijk-aan-Zee they have banned the sand dunes from human activity so people have to use the foot paths. This is so that constant human commotion doesn’t erode them.
The sand dunes in the Netherlands are unique to them because they are so important for the future of the people living there. If the sand dunes were to deteriorate then Holland’s flooding problems would greaten and most of the country would be under water. Other countries such as Britain have sand dunes but in Holland they are there for the survival of the country.
If this barbed wire was not here and the public were left to roam on top of the actual sand dunes without anything stopping them, then the human process of erosion would cause the sand dune to waste away.
