are operated to provide power during periods of peak demand. This operation scheme,
known as hydropeaking, contrasts with the lack of flexibility associated with thermal
units which cannot respond as quickly to ramping requirements (Svoboda et ah, 1997).
Base load is provided by the least expensive thermal units, but at some demand levels,
the marginal costs of thermal generation become very high, and hydropower units are
required. Peaking operations cause large abrupt flow variations downstream of
powerhouses, which can harm river and streamside ecosystems