1. What is the Drawdown Given Specific Capacity Formula?

The Drawdown Given Specific Capacity formula calculates the total drawdown in a well based on the discharge rate and the specific capacity of the well. This is a fundamental calculation in hydrogeology for assessing well performance and aquifer characteristics.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• Discharge (Q) — Rate of flow of water from the well (m³/s)
• Specific Capacity (Sc) — The quantity that a water well can produce per unit of drawdown (m²/s)
• Total Drawdown in Well — Reduction in hydraulic head observed at the well (m)

Explanation: This formula demonstrates the inverse relationship between specific capacity and drawdown - higher specific capacity means less drawdown for a given discharge rate.

3. Importance of Drawdown Calculation

Details: Accurate drawdown calculation is crucial for well design, determining pumping rates, assessing aquifer performance, and ensuring sustainable groundwater extraction without causing excessive drawdown that could affect nearby wells.

4. Using the Calculator

Tips: Enter discharge in cubic meters per second (m³/s) and specific capacity in square meters per second (m²/s). Both values must be positive numbers greater than zero for valid calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is specific capacity and how is it measured?
A: Specific capacity is measured by conducting a pumping test where discharge and corresponding drawdown are recorded. It represents the well's productivity per unit of drawdown.

Q2: How does drawdown affect well performance?
A: Excessive drawdown can indicate well inefficiency, aquifer depletion, or interference with nearby wells. It helps determine the optimal pumping rate for sustainable operation.

Q3: What are typical specific capacity values?
A: Specific capacity varies widely depending on aquifer characteristics. High-yield aquifers may have specific capacities exceeding 1 m²/s, while low-yield aquifers may be below 0.1 m²/s.

Q4: Can this formula be used for all well types?
A: This formula is generally applicable for most pumping wells, but may need modification for complex aquifer systems, confined vs unconfined aquifers, or wells with screen limitations.

Q5: How does time affect drawdown calculations?
A: This formula gives steady-state drawdown. For time-dependent drawdown analysis, more complex equations like Theis or Jacob equations are required that account for aquifer storage and time since pumping began.