The GATE Grind

GATE 2023 AG – Question 20

Soil and Water Conservation Engineering · Soil Mechanics · 1 mark · Multiple choice

Which porous-medium statement is incorrect?

  1. Seepage velocity is greater than Darcy velocity.
  2. Darcy velocity is not controlled exclusively by porosity.
  3. Seepage velocity increases with surface ponding.
  4. Unsaturated-soil Darcy velocity is always above saturated-soil Darcy velocity.

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: (D) Unsaturated-soil Darcy velocity is always above saturated-soil Darcy velocity.

Explanation

Darcy flux is $q=Ki$ and seepage velocity is q divided by effective porosity. Conductivity and gradient matter, not porosity alone. Unsaturated conductivity is generally lower than saturated conductivity, and no universal greater-than relation in D follows. Thus **D** is the intended false statement; comparisons of velocity presume otherwise comparable flow conditions.

More Soil Mechanics questions

All Soil Mechanics questions →