These measures may be electrical (switching of the generator outlet
to water resistance), mechanical (disconnecting the linkage between guide
and runner vanes of Kaplan turbines or providing automatic gate-
controlled outlets connected directly to turbine spiral casings), or struc-
tural (provision of special auxiliary outlets designed as bypasses for the
turbines).
In the case of power plants situated next to barrages the negative
effect of surge waves on navigation can also be reduced by suitable (auto-
matic) operation of the gates. Finally, the whole layout of the barrage and
plant can be designed so as to minimize surges (widening of head and tail
races, separation of the navigation channel from the power plant, etc.).
MULTIPURPOSE UTILIZATION OF WATERWAYS 467
Fig. 11.3 Waterways in central and eastern USA (Petersen, 1986)