Seepage calculation for flow net

[tzx9633]

Homework Statement

In the 3rd pictures , it's stated that q ( flow rate) = vA = kiA , so , i = hydraulic gradiene = difference in head between 2 points/ length . But , i am not sure why A ( area) is given by $$l_1$$ , $$l_2$$ and $$l_3$$ only ?

Homework Equations

The Attempt at a Solution

I think the author is wrong . It should be ($$l_1$$^ 2 ) ... instead , because it's forming the square elements( in 2nd picture) . Correct me if i am wrong .[/B]

 

[tzx9633]

Or the area is considered as length here ? So, only $$l1$$ , $$l2$$ and $$l3$$ are considered ??

 

[Chestermiller]

The other length forming the area is not the other side of the square. The area A is oriented perpendicular to the direction of seepage, and the other length is "into the page." They are getting the seepage flow per unit width into the page.

 

[tzx9633]

They are getting the seepage flow per unit width into the page.

Thanks !