Specific capacity (specific yield) of wells: select the correct unit definition Specific capacity is defined as the discharge of a well per unit drawdown. Which unit correctly represents this quantity?

Introduction / Context:
In groundwater engineering, specific capacity (also called specific yield of a well in pumping-test context) helps compare the performance of wells tapping different aquifers or constructed with different designs.

Given Data / Assumptions:

• Specific capacity = well discharge divided by drawdown at the well during pumping.
• Drawdown is measured in metres.
• Discharge is commonly recorded in m^3/hour (or m^3/day).

Concept / Approach:
Because specific capacity normalizes discharge by drawdown, its dimensional form is volume per time per length. A convenient unit is m^3/hour per metre of drawdown (equivalently m^2/hour). Using only m^3/hour would ignore drawdown; per m^2 is unrelated to the definition.

Step-by-Step Solution:

Verification / Alternative check:
Dimensional analysis: m^3/h divided by m equals m^2/h, confirming consistency.

Why Other Options Are Wrong:

• (a) and (b) omit drawdown, so they are not “specific”.
• (d) and (e) introduce area terms not in the definition.

Common Pitfalls:
Confusing aquifer “specific yield” (a storage parameter) with well “specific capacity”; here we refer to well performance in pumping tests.

Final Answer:
m^3/hour per metre of drawdown