and Dinorwic (1680 MW) in North Wales, and at Foyers (300 MW) and
Cruachan (450 MW) in Scotland. A major recently completed 1060 MW
pumped storage scheme is in Germany (Goldisthal).
Reversible pump–turbine and generator–motor machines are in use
nowadays, thus reducing the cost of a pumped storage plant installation by
eliminating the additional pumping equipment and pump house.
12.6 Head classification of hydropower plants
(a) Low-head plants
These plants have a gross head of less than about 50 m and are usually of
the run-of-river type, with or without pondage, the power house being an
integral part of the dam or barrage. Tidal power plants (Section 12.12.1)
are also low-head plants. The discharges are usually large in low-head
plants. The following are some typical installations of low-head plants: Pit-
lochry, Scotland (17 m); Owen Falls, Uganda (21 m); St Lawrence, Canada
(22 m); La Rance Tidal plant, France (3–11 m).
(b) Medium-head plants
These plants may be either locally or remotely controlled, with a head of
about 50–300 m, and some of the well known large medium-head installations
are: Castello de Bode; Portugal (97 m), Hoover, USA (185 m); Three
Gorges, China (113 m); Itaipu, Brazil (126 m); Guri, Venezuela (146 m);
Kasnojarsk, Russia (100 m).
(c) High-head plants
Most of the high head plants (head#300 m) are of the remote-controlled
type. The following are some of the installations of this type: Laures, Italy
(2030 m); Reisseck-Kreuzeck, Austria (1771 m); Chandoline, Switzerland
(1750 m); Mar, Norway (780 m); Cruachan, Scotland (401 m); Dinorwic,
North Wales (440 m).
12.7 Streamflow data essential for the assessment of water-power
potential
The gross head of any proposed scheme can be assessed by simple survey-
ing techniques, whereas hydrological data on rainfall and run-off are
essential in order to assess the available water quantities (see Shaw, 1994).
The following hydrological data are necessary: (a) the daily, weekly or
502 HYDROELECTRIC POWER DEVELOPMENT
