River Gradings

[billyshears]

What determines whether a river is a river or a canal? Is the River Chelmer (Chelmsford) graded as a canal? And, if so, why is it called the River Chelmer?

[halfadaily]

This should tell you what you want to know. http://en.wikipedia.org/wiki/Canals

[WoWo]

I was going to say, as the link agrees that canals are man made water ways rather than natural.

[Artemis]

The Chelmer is a river but on its way through Chelmsford has been tidied up to look like a canal by the use of concrete for its bank and bed.

[sddsddean]

This has also been done to stretches of the River Soar in Leics. and forms part of the Grand Union (Leicseter Arm) which runs to the River Trent west of Nottingham. In this case they are known as 'canalised rivers'.

[vehelpfulguy]

In very simple terms, a river existed before man came along, a canal only exists because man built it.

Having said that, many natural rivers have been changed by man with locks and so on (the Thames and Severn for example have locks)

One important difference is that rivers generally flow from high to low, the water flows in streams from high ground gradually joining other streams to become a larger river like the Thames.

But canals are generally flat. I know they go up and down, but only via locks. Often the longest stretch of canal, with no locks in it if possible, and often at the highest point, is completely flat, and is called the summit level.

This means that this summit level holds a huge quantity of water and can "feed" the locks at either end (every time a boat goes "down" a lock water is lost at the summit level.

Many reservoirs in cities were in fact built to feed canals and not supply local water for houses.

It always amazes me that so much effort was put in to building canals that moved goods at only 4 miles an hour.

The romans built roads 2000 years ago, would it not have been better 200 years ago to put the effort in building roads instead of canals ?

[dzug]

The romans built roads 2000 years ago, would it not have been better 200 years ago to put the effort in building roads instead of canals ?

They did build roads at the time but they were totally unsuited to the moving of heavy goods

One horse can pull a boat containing say 30 tons of coal. I forget how many horses and carts it takes to shift the same amount but it's quite a lot - and they churn up the road.