[elif]

Why is that? Britain is covered with a preindustrial canal network with thousands of locks which use nothing but channels doors and gravity. Literally made of wood and operated by hand.

Raising water on the low side to the level on the high side simply requires joining the two sides together.

If sea level is their high side, I don't understand why they can't use this supply forever.

[ianburrell]

I think the thing you are missing is that raising the low side means that the next boat to use the lock going up has to drain the high water into the low canal. The Panama Canal has system to conserve that water but some water still moves down the locks both for raising and lowering.

The British locks depend on a source of water at the top of the canal. I watched a video recently about Canal Trust rebuilding lock reservoir. The water levels definitely can limit if locks and canals are usable.

The Panama Canal has a reservoir at the top, Gatan Lake, but the water is low. Sea level is never the high side, it is always the low side.

[kwhitefoot]

Some lock flights have pumps to keep the ponds at the top full of water because they are near the highest point in the area so they can't refill naturally fast enough or simply to avoid depleting the upstream water source. See, e.g., https://en.wikipedia.org/wiki/Caen_Hill_Locks

[bombcar]

The sea level is the low side. The lake is the high side - which works great until the supply of lake water dries up.

The obvious solution is a sea-level tunnel a hundred miles long. Probably cheap. ;)

[ianburrell]

There has been proposed canal in Nicaragua. It would be 170 miles long and have locks to reach Lake Nicaragua.

Chinese company got concession to build decade ago, but didn't do anything and then went out of business.

[elif]

i dunno about tunnel... i am not a digger but I don't think digging 26 meters (highest point of canal) would require tunneling... just dredging.

[aidenn0]

You'd have to deal with the Chagres (assuming the current drought ends) as well.

The original excavation was done mostly dry and massive by any standards: 27kt of dynamite were used.

I'm also not a digger, but 26 meters of dredging over a 13km distance sounds crazy expensive. You would have to also widen the valley to prevent landslides into the canal.

[anonymfus]

Sea level is a low side on both ends of the channel.