From what I've seen it actually wouldn't change the rotation speed that much. Despite comparisons to Three Gorges and media calling it a "mega-dam" its design is completely different from a single giant dam with a massive reservoir.

The Yarlung Tsangpo Grand Canyon has a large bend and by digging tunnels through the mountains, water can shortcut a 2.2 km altitude drop in just 45 km, which gives it enormous amounts of kinetic energy which gets captured by five "dams" inside the tunnel. The mountains then function as a natural reservoir dam, so very little water gets lifted up, which is how the Three Gorges Dam slowed the Earth's rotation with its massive reservoir.

[–] quarrk@hexbear.net 20 points 3 weeks ago (2 children)

Imagine if we spent the last century focusing on this instead of fossil fuels and motor vehicles. So much nature destroyed for a mere century of production.

[–] GrouchyGrouse@hexbear.net 12 points 3 weeks ago

Imagine if they simply discussed the externalities of the fossil fuel industry the way they hem and haw over .000001% axial spin like holy shit it’s staggering they get away with this kind of narrative

[–] Le_Wokisme@hexbear.net 9 points 3 weeks ago

there's probably not many places on earth you can build this in particular. A lot, if not most of the easy hydro power sites are already utilized.