There are already concrete ideas for this. Due to the changing of rainy and dry seasons, the floating plant cover is already subjected to seasonal hydrological cycles. It could be possible to take advantage of this effect, for example with artificial floods. In this case, the dams are opened in a controlled manner to flush the plant material out of the bottlenecks where it typically accumulates and into less problematic areas.
Another idea makes use of the fact that the wind regularly blows the floating plants towards the riverbanks. By keeping the water level artificially high, this can be further supported. If the water level then drops in the dry season, the plants become stranded and can be removed together with the bound nutrients. They then serve local farmers as a low-cost fertiliser or can be used for the production of biofuel.
Not applicable to Switzerland
In Switzerland, the pollution of surface waters with nutrients has decreased considerably since the 1980s because of major efforts in water protection. Nevertheless, there are still some over-fertilised waters. However, there is a lack of natural plant vegetation to act as a buffer. Water hyacinth, which is widespread in the tropics, cannot survive in cool Europe.
Instead, the nutrient surplus promotes the growth of cyanobacteria, algae, and phytoplankton. Unlike the floating plants, however, these plants decay much faster, which leads to a lack of oxygen at the bottom of the lake. As a result, more nutrients are released from the sediments, which further increases over-fertilisation.