increase of the inflow of water into the locks filled by a long culvert should
not exceed dQ/dt0.6 m^3 s^2 at the beginning of the filling. The mean rate
of rise of the water level in these locks varies between 1.5 m min^1 and
2.0 m min^1.
For locks of large dimensions in plan and/or very high heads a more
complicated filling and emptying system, usually designed on the basis of
model studies (Novak and Cˇábelka, 1981), is necessary. There are many
locks in existence with various designs of filling and emptying systems.
An example of such a system used in the lock at Bay Springs on
the Tennessee–Tombigbee waterway, USA (L183 m, B33.50 m and
H26 m (Petersen, 1986)) is shown in Fig. 11.13.
The maximum head for which single-stage locks can be used is basi-
cally determined by the limit for which a rational filling and emptying
system – technically feasible and viable from the economic and water
resources point of view – can be designed. Surface flow and translation
waves, which would generate unacceptable forces in the mooring ropes of
the handled vessels, must be eliminated as far as possible. The filling veloc-
ity is usually limited by the danger of cavitation in the filling system.
Examples of very high heads used for a single-stage lock are H
42.5 m on the Ust–Kamenogorsk scheme on the Irtysh river, Russia
(lock dimensions 100 m18 m, minimum water depth 2.5 m), H35 m at
the Carrapatelo dam on the Duero river, Portugal, and H34.5 m at the
John Day Dam on the Columbia River, USA.
On canalized rivers also used for power-generating purposes, where
water requirements for navigation must be minimized, high heads are
overcome by means of either coupled locks (e.g. on the Gabcˇíkovo scheme
on the Danube), two-stage locks (e.g. on the Djerdab scheme on the
Danube), three-stage locks (e.g. in the Dnieprogress scheme on the
Dniepr river) or a whole cascade of locks (e.g. the Three Gorges Project
on the Yangtze River uses a cascade of 5 locks next to a 183 m high dam
with a total head of about 110 m each lock chamber of dimensions
280 34 5 (m) and capable of passing a 10 000 ton barge fleet) sometimes
482 INLAND WATERWAYS
Fig. 11.13 Filling and emptying system of the lock at Bay Springs on the
Tennessee–Tombigbee Waterway, USA (after Ables, 1978)
