July 18, 2022, Goeree-Overflakkee – Drought and Dikes. What is the effect of drought on our dikes? The water council manages dikes, dunes and quays on our island Goeree-Overflakkee. “They are all meant to hold the water back.” The effect of the drought on our water quality must also be monitored. “For example, why are there more dead fish / waterfowl during periods of drought and what can the residents do about the water quality on our island?” Read more below >>
protection against floods
Most of the flood defenses consist of clay. These flood defenses are very strong and can withstand drought well. In dry times, especially the peat quays or peat dikes are in the news. These may become less stable due to drying out and settling of the peat. In the management area of the Dutch Delta you can find peat quays along the Kanaal door Voorne and Keen and Boezemvliet. The Water Board inspects these dikes during times of drought.
What are the consequences of the drought for the grass on the dikes?
The turf acts as a covering for the dike and prevents runoff during high tide and wave action. The water council ensures that the sheep on the dike do not eat completely and / or pull the grass and grass roots out during drought. If the water council finds this, a grazing ban can be imposed on dikes.
What measures can be taken in the event of damage to peat docks?
In dry times, especially the peat quays or peat dikes are in the news. These may become less stable due to dehydration or precipitation of the peat.
The water council ensures that the quay can survive. Peat docks often involve adaptation. Initially, cracks may occur in the clay. These cracks are filled with clay granules and the quay is kept wet. When there are multiple cracks or major signs of damage, appropriate measures are taken to prevent weakening.
Drought and water quality
Why are there dead fish / waterfowl during periods of drought?
When it is dry and hot, the water temperature rises and plants and bacteria grow faster. This can cause a lack of oxygen in the water, causing fish to die. In addition, there is a greater risk of botulism if carcasses of dead animals remain. Therefore, the water council removes the carcasses as soon as possible and the ditch or canal in question is rinsed with clean water. There is also a greater chance of blue-green algae during drought.
What can residents do to keep the water clean?
Do not feed ducks. In summer there is sufficient food available for (water) birds. The bread, which ends up in the water and is not eaten, ensures that there is a lot of food in the water, so that bacteria and plants can grow faster. Do not feed fish, it also ensures fertilization of the water. And the decomposition of leftover food requires oxygen, so there is less oxygen available for fish.
What influence does salt have on water quality?
Fresh water within the dikes is crucial for water quality. It is used for irrigation of crops, but the flora and fauna are also adapted to water with a certain salt content. Fish, plants and crops can not withstand major changes in the salinity of the water.
What is botulism?
Botulism is a form of food poisoning caused by a bacterium commonly found in water with low oxygen levels. Temperatures above 20 ° C and a protein-rich environment (for example a dead bird) are ideal conditions for this bacterium. The bacterium then multiplies very quickly and secretes a toxic substance (botulin). Waterfowl and fish in particular are affected by this. They show signs of paralysis and eventually become suffocated. Because botulism is highly contagious to animals, it is important that sick and dead animals be removed as soon as possible.
Botulism in bathing water also poses a danger to humans. Not so much because of botulinum, but because of the risk of contamination with all sorts of other pathogens that occur in the rotting carcasses. Therefore, do not go into the water in places where dead animals float, and do not let children play there. Do not touch the sick or dead animals. Have you seen a dead animal? Report it to our water council counter on tel. 0900 2005005 or by email firstname.lastname@example.org. Always state the exact location along with your report.
What are blue-green algae?
Blue-green algae are not actually algae or seaweed. It’s bacteria. Another name for it is cyanobacteria. They feed on light, carbon dioxide and nutrients in the water. If there are many nutrients in the water, the water stands still and it is hot, it can give a blue-green algae bloom. During flowering, the many blue-green algae can form a floating layer. Because the bottom of the floating layer dies, toxins (toxins) end up in the water. Not all blue-green algae produce toxins. If the water has a strange color, or if there is a foul-smelling layer of algae manure on the water, do not swim and inform our customer contact center via 0900 2005005 or via e-mail email@example.com.
Blue-green algae can be toxic to humans and animals. The water council will flush the ditch or canal in question with clean water. The province indicates what the council is for the bathing water places (warning or bathing ban). It is also extremely unwise to swim in other waters where blue-green algae occur, given the health risks. Check the swimming water.nl website for the quality of the bathing water in your area. You can also download the bathing water app.
If you come in contact with blue-green algae, or if you ingest it while swimming, you may experience irritation of your eyes or skin. Other complaints include headaches, stomach and intestinal problems and in some cases even major health problems. If you have come into contact with blue-green algae, rinse well under the shower (bathing is always a good idea after swimming in surface water).
text Water Board Dutch Delta