The single headrace tunnel later splits into two long, diameter steel-lined penstocks ( tunnels ) and the water makes a rapid descent down a final vertical penstock into the power station.
22.
When energy demand is high, water from the upper reservoir is released down to the underground power station via a single long headrace tunnel which splits into two tunnels before each separate into two long penstocks.
23.
While Jinping-I relies on a conventional tall dam and large reservoir to supply water, Jinping-II uses a much smaller dam, located 7.5 km downstream of Jinping-I, to divert water into four 16.6 km long headrace tunnels.
