Fish friendly River Bank Erosion Protection
Conventional civil engineering bank protection has
usually been done by re-sloping the bank, and then applying a thick
layer of blast rock (riprap) from the toe of the bank up to the
appropriate flood level, such as the 200 year return period flood.
Where the current is very fast and the bank is eroding towards valuable
buildings or infrastructure, this more solid and certain method
can still be the best approach. Problems in use of riprap include
a lack of habitat diversity along the bank, and increased flow velocities
along the riprap being passed downstream, where further erosion
can be initiated. Riprap slopes can be modified to reduce flow velocities
and provide some fish habitat.
However, on lower gradient streams and rivers, an
alternative approach of a series , or field, of bendway weirs or
stream barbs slows flow velocities along the eroding bank, which
with vegetation planting on the river bank stabilizes the bank.
Bendway and stream barb weirs create more diverse fish habitat,
and reduce flow velocities passed downstream.
Weirs require regular inspection, and maintenance
if required, to function properly over the long term.
Each situation requires a slightly different design
and construction to function properly. Gooding Hydrology is a leader
in weir field design and construction.