Question

gradually varied flow” and, particularly, a “backwater curve”
a.   What is the method or concept in question and how is it used?
b.   Why does it matter to engineers or to engineering hydrologists? Why should we care?
c.   What are the primary strengths or weaknesses of the method or concept?
d.   What would have made it easier for you to understand the method or concept? Here, for example, you might imagine that you are giving advice to a friend taking this course next year: what do you think they would really benefit from knowing about this concept?

Answer 1

Gradually varying flow:

It is the study and 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(no turbulence).

Backwater curve:

The change in water surface of an 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.

A. This is from open channel flow concept. Which is used to determine the depth of waterflow and velociby of waterflow.by knowing this concept we can know whether the flow is laminar or turbulent etc.

B.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. Gradually varied flow generally applies at long distances, it is useful  to know channel bed slope and channel friction.

C. Strengths:

-we can calculate the depth of Waterflow.

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

Weaknesses:

-it is applicable for only study state flow only

-One Dimensional (can only calculate average cross sectional water velocity)

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

D.By YouTube lectures I can understand this concept easily.

By knowing this concept we can solve so many problems related to depth and velocity of culvert,river or dam.and we can know bed slope and friction of water flow.