ECOHYDRAULICS

What is this paradigm about?

The “From White Rivers to Green Rivers” paradigm is not only a special issue in our flagship community journal, but it was also part of the 2023 IAHR World Congress in Vienna.

Rivers around the world are undergoing a profound transformation. Once characterized by open expanses of white sand and gravel bars, many river landscapes are increasingly becoming green, covered by grasses, shrubs, and mature trees. This shift is not simply a change in appearance; it reflects fundamental changes in river processes, ecosystems, and human interactions with watercourses. Human activities within catchments, river restoration measures, flood-control strategies, and changing climatic conditions are among the factors driving this transformation. Reduced gravel deposition, rising temperatures, and the spread of invasive plant species can accelerate vegetation growth, fundamentally altering river morphology and ecological conditions. These changes create opportunities but also challenges. Riparian vegetation can contribute to biodiversity, provide valuable habitats, and enhance carbon sequestration. However, it can also influence flood conveyance, sediment transport, channel stability, and the development of river islands. Understanding these competing effects is essential for sustainable river management.

Against this background, the paradigm “From White River to Green River” brings together indivuals worldwide to explore the complex interactions between vegetation, hydrology, sediment dynamics, and river morphology. The contributions addressed topics ranging from vegetation-induced riverbed re-structuring and channel evolution to fish habitats, flood impacts, invasive vegetation, and ecological succession in recovering rivers. The central message of the paradigm is clear: river management must move beyond viewing vegetation as merely an obstacle to flood conveyance. Instead, vegetation needs to be understood as an integral component of dynamic river systems. Ultimately, understanding the transition from white to green rivers is essential for developing healthy river landscapes that balance flood protection, biodiversity, and environmental sustainability.