UTRECHT – How much waste ends up on Dutch beaches from the sea? Where is it from? And under what conditions does it wash ashore? To find answers to these questions, researchers from Utrecht have mapped out tens of thousands of kilos of washed up waste on Dutch beaches. According to the researchers, the results make it possible to predict where and when waste will wash ashore, so that it can be cleaned up in a more targeted manner.
The researchers did not go through those tens of thousands of kilos of waste themselves: they worked with a dataset from the North Sea Foundation. This organization organizes so-called beach cleanups in which volunteers clean up waste on the beach. In this way, the researchers were able to sort through six years of data. This shows that there is currently between 17,000 and 30,000 kilos of waste on Dutch beaches. “That is an average of 20 to 80 kilograms of waste per kilometer of beach,” said Mikael Kaandorp, one of the researchers.
Looking forward
By comparing the data with weather data, the researchers were able to determine under which weather conditions mainly waste washes ashore. And that way you can also look ahead, says oceanographer and climate scientist Erik van Sebille. “If you expect, based on the weather forecasts, that a lot of waste will wash up on a certain day and a certain location, you can already make a call to clean it up before it washes back into the sea again. That is extremely important, because it is much easier to clean up waste on the beach than in the sea.”
Most beach waste was found around Castricum and Bergen. According to researcher Kaandorp, there appears to be relatively less waste on the beach in Zeeland. “The coast is more erratic there and borders less directly on the North Sea. And we think that the waste there washes back into the sea earlier because the tide is more variable there.” Less waste is also arriving on the beach in the north and on the Wadden Islands.
Straight shorelines during low tide
There are lessons to be learned from the research for waste disposal in the future. If you want to get rid of garbage effectively, it’s best to look at the relatively straight stretches of coastline and the coasts that are less jagged. The most convenient time to take your grab to the beach is during low tide, especially during the week around neap tide, when there is less difference between high and low tide.
The researchers do have an important comment about the data used: the beach cleanup people mainly cleared up when the weather was nice. “So we don’t have that much data on the amount of waste in bad weather conditions. That may mean that our model is less accurate for the winter season. So we call for more frequent beach cleanups in the fall and winter.”