Section 4: Soil and Water Conservation Engineering
Soil Mechanics
Subtopic: Permeability and seepage analysis
Question Statement:
Which of the following statements are CORRECT regarding flow net properties in isotropic soils?
Options:
(A) Flow lines and equipotential lines intersect orthogonally at $90^\circ$
(B) The quantity of seepage in each flow channel is equal
(C) The potential drop between any two adjacent equipotential lines is constant
(D) Flow fields in a properly drawn flow net are approximately curvilinear squares
Answer Key:
A, B, C, D
Step-by-Step Solution & Explanation
All statements characterize an orthogonal flow net in isotropic media:
• Orthogonality: Flow lines are streamlines perpendicular to potential lines ($∇\phi ⋅ ∇\psi = 0$).
• Equal flux: $\Delta q$ is identical across all channels.
• Equal head drop: $\Delta h = H / N_d$ is uniform across successive lines.
• Elementary field geometry: In isotropic soil where $k_x = k_z$, aspect ratio $b/l \approx 1$, forming curvilinear squares.