Question

Which of the following statements regarding Hooghoudt's equation are correct?
(A). Gives the relation between the spacing of drains and the height of the water table.
(B). Darcy's law is valid for the flow.
(C). The soil is heterogenous.

Choose the correct answer from the options given below:

• (B) and (C) only.
• (A) and (C) only.
• (A) and (B) only.
• (C) only.

Hint:

Hooghoudt's equation is the classic steady-state subsurface drainage model.
Key assumptions: steady-state flow, homogeneous soil, and validity of Darcy's Law.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Hooghoudt's equation is a steady-state drainage equation used to design the spacing of parallel subsurface tile drains.

Step 3: Detailed Explanation:
Let us analyze the assumptions and parameters of Hooghoudt's equation:
-

Statement (A): The primary purpose of Hooghoudt's equation is to calculate the spacing (\(L\)) between subsurface drains based on the hydraulic conductivity of the soil, the drain discharge rate, and the height of the water table (\(h\)) midway between the drains. Thus, (A) is correct.
-

Statement (B): The derivation of Hooghoudt's equation assumes steady-state, laminar, saturated flow of groundwater towards the drains, where Darcy's law is fully valid. Thus, (B) is correct.
-

Statement (C): The basic Hooghoudt equation is derived assuming the soil is completely

homogeneous and isotropic. While it can be modified for a two-layered soil profile, the fundamental assumption is homogeneity, making (C) incorrect.
Therefore, only statements (A) and (B) are correct.

Step 4: Final Answer:
The correct option is 3, which corresponds to (A) and (B) only.