Research program Hydraulic Engineering and Ecology

Rivers and streams are more than just water; they also include the adjacent land. In near-natural rivers and streams, the transition between water and land is continuous, meaning there is a tight, blue-green coupling.

Near-natural rivers and streams are ecosystems of enormous diversity. This biodiversity is reflected in the habitats - from very wet to very dry, from small to large stones, from sparse to dense vegetation - and, in the above-average species richness of animals, plants, fungi and lichens.

During floods, rivers and streams also transport bedload; i.e., gravel, stones, and boulders. Natural rivers and streams are supplied with sufficient bedload from upstream. Artificial obstacles such as weirs can stop the bedload supply.

For land acquisition and flood protection, many Swiss rivers and streams have been straightened and channelized over the past 150 years. Today, they resemble monotonous drainage channels that are uninhabitable for many riverine organisms. With restoration projects, the shape and structure of rivers and streams are enhanced.

Like a mosaic, near-natural rivers and streams consist of many different parts - water, unvegetated gravel banks, softwood or hardwood floodplain forests. Floods renew the habitat mosaic; e.g., a gravel bank is removed in one place and a new one is created elsewhere. This dynamic is characteristic of riparian areas and critical to maintaining biodiversity.