Inputs
Enter water levels as depth below ground. Use the same reference for all three measurements.
Example Data Table
| Static level | Pumping level | Current level | Recovery time | Well diameter | Notes |
|---|---|---|---|---|---|
| 6.2 m | 11.0 m | 7.5 m | 45 min | 15 cm | Typical irrigation test after short pumping. |
| 8.0 m | 12.4 m | 10.1 m | 60 min | 20 cm | Slower rebound suggests lower recharge conditions. |
| 4.5 m | 7.8 m | 4.9 m | 30 min | 10 cm | Fast recovery indicates strong well response. |
Formula Used
This calculator treats all levels as depth below ground.
- Initial drawdown = Pumping level − Static level
- Residual drawdown = Current level − Static level
- Recovered drawdown = Initial drawdown − Residual drawdown
- Recovery percentage = (Recovered drawdown ÷ Initial drawdown) × 100
- Recovery rate = Recovered drawdown ÷ Recovery time (hours)
If you provide well diameter, casing storage recovered is estimated as:
Recovered volume (L) = π × (d/2)² × Recovered drawdown × 1000
How to Use This Calculator
- Measure the static level before you start pumping.
- Pump for irrigation, then record the end pumping level.
- Stop pumping and wait a known recovery time.
- Measure the current level after the waiting period.
- Enter values, then press Calculate to view results.
Use the recovery percentage to compare different irrigation cycles. Use recovery rate to judge how quickly water rebounds under similar pumping stress.
For better consistency, take readings at the same time intervals.
Why Well Recovery Matters for Irrigation
Well recovery describes how quickly groundwater levels rebound after pumping for garden irrigation. Fast recovery supports consistent watering schedules, while slow recovery can trigger pump cycling, reduced yield, and stress on plants. Tracking recovery also helps protect the aquifer by avoiding excessive drawdown during dry seasons.
Key Measurements and Field Practices
Use a weighted tape, sounder, or pressure transducer to measure depth below ground. Record a static level before pumping, then capture the pumping level at shutdown. After waiting a timed interval, measure the current level. Keep the same reference point, note weather, and avoid measuring while the pump is running.
Interpreting Recovery Percentage and Rate
Recovery percentage compares rebound to the initial drawdown, making tests comparable across different pumping events. Recovery rate expresses rebound per hour, which is useful for planning irrigation windows. If recovery stalls, it can indicate limited recharge, clogged intake screens, or interference from nearby pumping.
For repeatable tests, keep pump runtime similar and use the same recovery interval each time. Consider running two intervals, such as 15 and 60 minutes, to see whether recovery is linear or slowing. In sandy formations recovery may be rapid early, while fractured rock can show delayed rebound. Consistent notes improve troubleshooting. If recovery is poor, reduce demand, add storage, or consult a hydrogeologist locally.
Using Casing Storage and Pumped Volume
When well diameter is known, recovered casing storage estimates the water volume represented by the rebound inside the casing. This helps distinguish short-term storage effects from formation recharge. If you also enter pumping rate and duration, pumped volume provides context for how hard the well was stressed during the test.
Operational Decisions and Recordkeeping
Log results by date to spot seasonal patterns and long-term change. Set practical thresholds, such as pausing irrigation when recovery is below a target percentage after a standard wait time. Use these trends to adjust emitter flow, zone runtimes, and watering frequency, and to schedule maintenance or well assessments.
FAQs
1) What is a good recovery percentage for a garden well?
Many small irrigation systems aim for 80–100% recovery within a consistent wait period. The best target depends on your well, aquifer, and demand. Compare results over time under similar pumping conditions.
2) Why must pumping level be deeper than static level?
Static level is the resting water depth. Pumping lowers the level, so the end pumping measurement should be deeper. If it is not, the readings may be reversed, taken from different reference points, or influenced by measurement error.
3) How long should I wait before measuring recovery?
Choose a repeatable interval that matches your operation, commonly 15–60 minutes. Longer waits show more rebound but may hide short-term problems. Use the same interval for trending, and add a second interval if you want a fuller picture.
4) Does well diameter change the recovery percentage?
No. Percentage recovery is based on drawdown depths, so diameter does not affect it. Diameter is used only to estimate casing storage volume, which helps translate rebound into liters and compare storage effects.
5) Why does recovery slow down over time?
Recovery often follows a rapid early rebound from casing and nearby formation, then slows as water moves from farther away. Lower recharge, seasonal decline, or nearby pumping can also reduce the late-stage recovery rate.
6) Can I use this calculator for ponds or tanks?
It is designed for wells where water level is measured as depth below ground after pumping. For tanks or ponds, use volume and surface-area methods instead, because the geometry and recharge behavior differ.