Delta Life 9

› What is the main difference with silt? Sand grains are much larger than silt particles and they settle quickly. They do not stick together or to other materials. › Where does sand create challenges? In estuaries and on the coast where the combination of sea level rise, land sub­ sidence and less sand in the river leads to the erosion of the coast. Too little sand ultimately results in flooding. Extra sand is actu­ ally needed because the sea level is rising. › Why is sand important for us all? Sand from the river and the sea raises land naturally and so it protects the coast. Dune areas are home to unique plant and animal species. › How does sand 'work'? One gram of sand contains about 100 thousand grains covering a total area of ​ approximately 0.01 square metres. Sand covers relatively small distances in water. We have to transport it actively to where it is needed. Sand does not stick together. Dunes and other height differences are created in sandy environments exposed to wind. › What does sand do for nature? Sandy nature is low in nutrients and the living conditions are often more ex­ treme. Rare, unique species are found here. Pioneer species such as marram grass and couch help to retain sand. › What smart options do we have for sand? The advantage of sand is that it is easy to move and it is still flexible afterwards. Solutions with sand basically come down to removing it from where there is too much and finding the right place to deposit it. Sand motors and strategically placed artificial sandbanks just off the coast replenish the coast nearby. We call this process 'nourishment' or 'suppletion': currents take the sand to where it is needed. BY PJOTR VAN LENTEREN / IMAGE ISTOCKPHOTO SAND Sand and silt are the best known building blocks supplied by water to make land. Together, they shape the coast and estuaries, but in very different ways. What are the options for these natural building materials? SEDIMENT MANAGEMENT DOSSIER