SMALL DAMS PETITS BARRAGES

� The mentioned dewatering elements must be regularly maintained if a reliable function
should be secured steadily. It is especially necessary to clean the foot ditches of fallen leaves,
accumulated dry grass and of other undesirable stuff, which could restrict their function.
However, due to their good accessibility in comparison with the inner dewatering systems, the
main advantage of the elements for surface drainage is their easy checking, trouble-free
maintenance and relatively easy repairs.
Other technical solutions of surface dewatering of dams are used in various countries
locally, according to the local conditions. It is rather a question of unique constructions which
should not be generalized.
5.10 SLOPE PROTECTION
5.10.1 Upstream Slope Protection
The upstream slopes of earthfill dams must be protected against destructive wave
action. In some instances, provision must be made against burrowing animals. The usual
types of surface protection for upstream slopes are rock riprap, either dry dumped or hand
placed, and concrete pavement. ICOLD Bulletin 91, published in June 1993 specifically deals
with protection of upstream slopes for fill dams and it is important to be consulted.
Other types of protection for small dams that have been used are soil cement pavement,
and (on small and relatively unimportant structures) wood and sacked concrete. The upstream
slope protection should extend from the crest of the dam to a safe distance below minimum
water level (usually several feet). In some cases, it is advantageous to terminate the slope
protection on a supporting berm, but it is generally not required.
Where the water level in the dam can be expected to fluctuate widely, or where a high
degree of protection is required, the use of a rock layer, usually called “rip-rap” is the most
effective method of control, as illustrated in Fig. 5.11.[4]
Fig. 5.11 – Typical rip-rap layer for the protection of the upstream slope (Lewis, 2002).
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