Flow patterns around longitudinal training dams

Abstract

With the
intention to reduce the negative  effects
of ongoing bed erosion, as well as to  improve
several other river functions such as  protection
against floods, provision of safe and  efficient
navigation and ecology, a ‘pilot project 
longitudinal training dams’ was initiated. The  training dams have recently been implemented  in the Waal between Tiel and Sind Andries. In  this project, river groynes have been  completely removed and replaced by dams  that lie parallel to the river bank. With
help of  the longitudinal training dams,
a two-channel  river system is created in
which the river is  divided into a main
and side channel. The  dams are placed in
a continuous manner with  openings in
between that are relatively small  compared
to the dam length. At the beginning  and
end of the dam an inlet and outlet region is 
situated, as shown in Fig. 1.  The
combination of inlet and openings  allows
for water and sediment to be divided  between
the main and the side channel. Both  inlet
and openings are constructed with the  help
of a porous rock-layer. The crest heights 
can be altered by adding or removing stones.  This is expected to influence the amount of  water and sediment entering the side channel  and can therefore be used as a regulation
tool.