why does the river Idle flow so quickly over flat land?

Answer 1

It isn't all THAT flat. For example, between Retford and Bawtry, there's an elevation drop of over 25 feet over a little more than 8 miles. What section of the river do you mean? Also, don't forget that depth x width vs. flow will decide the speed. In areas where the river is constrained, it will naturally flow faster.

Answer 2

The old professor says: River waters in mountains (often their sources) flow quickly because of the steep gradient. True, there is much resistance in a rough bed, but gravity and a narrow bed overcomes much of it. At lower and flatter terrain, the river spreads out and meanders. This tends to cause velocities to decrease. More surface area on the bottom can add to the friction, which may be modified by the smoother bed. Most river velocity here is due to momentum and a smoother base. My guess would be the reason for the Idle river's velocity would be momentum and a lack of serious meandering.

Answer 3

Contrary to popular myths that have generated such songs as Old Man River - a river will flow quicker at the end of its journey over flat land as it has less resistance to overcome. The river at source is generally flowing ave high ground and the pebbles/rocks etc cause resistance and therefore actually slow the flow of water.

Answer 4

the other answers don`t take into account the river is tidal,in a full cycle --it flows to the sea--for a time it do`s not appear to flow--then it flows inland-then it flows to the sea again.the tide forms a gradient in the river which effectivley makes it flow faster.

Answer 5

its like ice skating- on a smooth surface there is little friction but on a rough surface, rapids are create which slow down all the water as it is deflected upwards, hitting the water that is trying to gain momentum which cant therefore travel that fast.