They were made for horse drawn barges of course and you'd need a lot of horses for (say) Rhine style  barges of 1000 tonnes plus which shift a LOT of bulk goods particularly fuel.

That's not to say I don't advocate a canal style solution. I do.

Pownall's

Grand Contour Canal

 concept (denominated in white with red borders) is an interesting one

More recently, one of the most remarkable canal schemes ever was proposed as recently as WW2.  J.F. Pownall observed that there was a natural 'contour' down the spine of England, around the 300ft level.

In 1940 he put forward the idea that this could be used as a large (by British standards) ship canal. Pownall's Grand Contour Canal would have taken 300-ton continental-size barges from Teeside to Lancashire, Gloucester, London and Southampton, with no locks and just a boat lift at a few stopping points.

Such a concept could serve to move water from where it mainly falls (the North West) to where it's mainly needed (South and South East), and also as a transport artery for decent size barges connecting to the main navigable rivers.

Moreover, such a scheme could be "self funding" - indeed profitable - if the land within (say) 1000 metres of it were used for (say) eco development using a non-toxic development model.

ie the increased land rental values along the route would not all go to private landlords and developers but would be used to pay the cost of building and operation.

Any excess spoil (particularly rock)  could be used to build tidal lagoons on suitable West coast sites, and also a new Thames Barrage downstream of the existing one, with lots of power capacity.


"The future is already here -- it's just not very evenly distributed" William Gibson