Question

Consider the flow net shown below: The sides of the region are groundwater divides; the top boundary is the water table; and the bottom is an impermeable boundary. A) Label the equipotential with the appropriate value of hydraulic head (m); B) Draw arrows on the streamlines indicating the direction of groundwater flow; C) Label all recharge and discharge areas; D) Indicate at least one area within the flow net where flow is relatively fast, and one area where flow is relatively slow; and E) Determine the water level (hydraulic head, in m) in wells A and B. 50 B 40 30 . 20 10 10 20 40 60 30 70 80 90 100 50 * (m) Figure 7.19 Flow net for Problem 3.

Answer 1

Discharge Recharge 50 Recharge I 42 44 - Discharge 40 lik 40 32 35 B 35:37 32 30 21 14 ,25 20 last slow flow flow 0 20 30 40 50 60 70 80 90 loo

The water level at $A=11.5m \approx 12m$

The water level at $B=35m$

Answers are directly obtained from the graph.

Hydraulic head of equipotential lines are the value corresponding to y axis.

The direction of flow is from higher potential to lower potential.

The recharge and discharge is according to the direction of flow of equipotential lines, i.e. start points of equipotential line gives recharge and end points give discharge.

Faster will be the flow at densely spaced portion of graph and the other slower.

The water level of A and B are the value of y axis corresponding to the lop boundary of water table.