Author(s): Gerald Muller, Laura McFadzean

Linked Author(s): Gerald Muller

Keywords:

Abstract: Beavers lived in the rivers of Eurasia and North America for more than 20 million years. They are termed ‘ecosystem engineers’, since their dam building activities dramatically change the characteristics of river systems. They shape river valleys, and create new and enhanced ecosystems which cannot exist without them. The disappearance of beavers in North America led to severe problems such as incision, groundwater lowering and loss of land value. Despite these profound effects, little appears to be known about the engineering characteristics of beaver dams. Recently, artificial beaver dams have been introduced to restore these streams. Again, there appears to be little engineering input in these restoration efforts. A research programme was initiated at Southampton University to compile and analyse the engineering information about natural and artificial beaver dams. It was found that beaver dams are built in rivers of up to 33 m width. They modify the flow duration curves, in-crease ground water retention, reduce gradient and sediment transport, trap sediment and create enhanced ecosystems. Model tests showed that beavers employ interesting construction techniques, creating semi-permeable dams able to withstand flow volumes of up to 1.34 m3/s per meter width for a 1.4 m high dam. The work will allow creation of novel, nature based, cost-effective solutions for ecosystem redevelopment and river re-naturalisation.

DOI: https://doi.org/10.3850/38WC092019-0580

Year: 2019