Question

1. What is “gradually varied flow” and, particularly, a “backwater curve”?
2. why is it important in the engineering/ hydrologic (why it matters)
3. what are its strengths and weaknesses.

Answer 1

1.Gradually varying flow:

It is defined as the study non uniform flow in a channel in which there are gradual changes in water depth and velocity.but in this case water surface is smooth.

Backwater curve:

The change in longitudinal profile of open channel flow by an obstruction and the curve is formed by the back water flow in channel by that obstruction. i.e. the increase in the water depth when it approaches to the weir or dam accross the channel.

2.When we design a weir or dam it is important to know that the how much of water is flow through that dam or weir and need to know that how much water is stored when the gate is closed.by knowing the backwater flow we know that how much the height is rises at weir dam then we can design the dam height.

3. Strengths:

-we can know the volume of water flow

-we can know the height of water flow upon the weir or dam

Weaknesses:

-it is hard to know that the height of backwater flow when the water velocity is more

-when a rapid flow is there it makes turbulace at the surface of water,in that time also it hard to know the height of backwater flow.