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 ?
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]