Re: Canals of Brum
With regards to the lousy weather & flooding in many places, why don`t canals flood? Is it because of the different heights, & what about the canal at the end of the system. Where does the water go to from there.?
Long explanation but it gives some explanation why canals don't (often) flood.
First you have to realise that rivers are "natural", are always flowing, and will take the easiest path. They are nearly always at the bottom of valleys, or certainly at the lowest point in an area, so water in a river (plus all its feeders) will all flow to this lowest point. And if there is too much water the river will flood as it has nowhere else to go.
But canals are man made, and often "above" the lowest point (if you walk along some canals you often find yourself walking above the land either side of the canal).
But the key thing is that most canals are FLAT, at least for much of their route, so the water does not "flow" like a river.
One important thing to consider with canal design is that every time a person uses a lock the water flows out the lock from the high point of the canal to the lower point in the canal, so water is constantly being lost from the highest point.
So when people designed canals they knew that they had to have the highest point of the canal as long as possible (with no locks) to "store" the maximum amount of water to help feed the locks at either end. This long stretch of canal was called the "summit pound".
The summit pound always needs to be topped up with water as it is always losing water when people use the locks at either end. This is why areas like Earlswood Lakes were created, by damming a valley and storing water ready to top up the summit pound.
However if the locks are not being used much (like in winter) then the summit pound does not need to be topped up, and hence has far less chance of flooding.
So I think the main reason canals don't floods is that they are "flat", and don't flow like a river.
As others have said, there are also various outlets built in to canals to send water off the canal to nearby rivers and lakes.