World Rivers Day – Sustainable use of biomass from river maintenance

Since 2005, World Rivers Day has been held every year on the fourth Sunday in September. It reminds us worldwide of the ecological, cultural and economic importance of rivers and raises awareness of challenges such as pollution, overuse and climate change. At FiW, we deal with these issues in our daily research work. For example, we study how mowing residues, i.e. grass and green cuttings from riverbank mowing, can be put to good use. Instead of disposing of them at high cost or leaving them on site, which can enrich nutrients and harm riverbank vegetation, we examine to what extent material and energy recovery is possible and meaningful.

World Rivers Day was initiated within the United Nations Environment Programme (UNEP) and is now celebrated in more than one hundred countries with local activities. These include clean up campaigns as well as professional events. The aim is to strengthen awareness of the role of rivers as lifelines of our society.

At FiW, the sustainable development of river and watercourse landscapes is also a central focus. Among other things, we investigate how biomass flows from river maintenance can be used effectively. One key area is mowing residues produced during riverbank mowing. In many places, this material is still disposed of or left along the watercourse, which can impair biodiversity of riparian habitats and water quality.

To identify alternative uses, we develop GIS based models that can estimate the amount of mowing residues along riverbanks. These models take into account the volume of material, the frequency of maintenance, logistical factors such as transport routes and available infrastructure, as well as relevant vegetation properties such as energy density.

By validating the models with practitioners, it is possible to determine potentials for material and energy recovery. The aim is to combine ecological benefits such as improved water quality with economic synergies.

The example of mowing residues shows that rivers are more than hydrological systems. They are also interfaces for ecological, technical and economic issues. FiW research demonstrates how river maintenance can be made more sustainable and contributes to preserving rivers as diverse habitats.