Up to 40 times more waste in rivers due to flooding
The research was carried out by Caspar Roebroek and Tim van Emmerik (Wageningen University & Research) in partnership with Dirk Eilander, a hydrologist at the Institute for Environmental Studies (IVM), VU Amsterdam, and scientists from the European Centre for Medium-Range Weather Forecasts. The study, which was published recently in Environmental Research Letters, shows that severe and frequent flooding, in particular, causes enormous amounts of waste to be displaced into rivers. There are major differences between countries: in some areas the amount of waste doubles, while in other regions 20 to 40 times the normal amount of waste ends up in the rivers. This is the case in densely populated delta areas such as in Bangladesh, Vietnam and Egypt.
Fewer flood control measures means more waste in rivers
The analysis shows that in areas with fewer flood control systems, such as dikes and dams, more plastic waste is displaced during flooding events. In general, those countries not only have more unprocessed waste but more flooding occurs too, and these two problems compound one another. “To analyse the effect of flood control systems, we used the FLOPROS dataset developed by our research group at the Institute for Environmental Studies. We applied this data in the study to get a more accurate picture of the amount of plastic that is potentially displaced during flood events and that can end up in the ocean after being washed away by the river”, says Eilander, who is currently working on a PhD research on flood risks around the world funded by a VIDI grant from the Dutch Research Council.
Future flood impact studies
“Most flood impact studies focus on the direct impact on buildings and people, but this research shows that other impacts, such as the displacement of waste, cannot be ignored when designing flood adaptation strategies”, says Eilander. The results indicate that floods and other natural disasters should be given a more prominent place when devising strategies to reduce the problem of waste in rivers. More research is needed to find out exactly how flooding causes plastic waste to be displaced.