Calculator Inputs
Enter consistent field data. The calculator converts values internally to SI units for computation and then reports engineering outputs clearly.
Example Data Table
| Scenario | K | Δh | L | b | W | nₑ | Q | Seepage Velocity |
|---|---|---|---|---|---|---|---|---|
| Fine Sand Example | 0.0001 m/s | 6 m | 150 m | 8 m | 25 m | 25% | 69.12 m³/day | 1.3824 m/day |
| Medium Sand Example | 0.0003 m/s | 4 m | 100 m | 10 m | 20 m | 28% | 207.36 m³/day | 3.7029 m/day |
| Silty Sand Example | 0.00003 m/s | 5 m | 120 m | 7 m | 18 m | 18% | 13.61 m³/day | 0.6000 m/day |
Formula Used
Darcy discharge: Q = K × A × i
Hydraulic gradient: i = Δh / L
Cross-sectional area: A = b × W
Specific discharge: q = K × i
Seepage velocity: v = q / nₑ
Transmissivity: T = K × b
Travel time: t = distance / v
The anisotropy or field factor multiplies conductivity to create an adjusted effective conductivity for quick screening calculations.
How to Use This Calculator
- Enter a scenario name so your exported files stay easy to identify.
- Select the aquifer type and choose the unit set for heads and lengths.
- Input hydraulic conductivity and its matching conductivity unit.
- Enter heads at two points that share the same reference datum.
- Provide flow path length, saturated thickness, and flow width.
- Enter effective porosity and the travel distance you want to evaluate.
- Add an anisotropy or field factor if you need a simple correction.
- Press the calculate button to view outputs above the form.
- Use the CSV or PDF buttons to export the current calculation report.
FAQs
1. What does this calculator estimate?
It estimates hydraulic gradient, specific discharge, Darcy discharge, seepage velocity, transmissivity, annual volume, and approximate travel time from common aquifer inputs.
2. Why is seepage velocity higher than Darcy velocity?
Darcy velocity uses the full cross-sectional area. Seepage velocity divides flow by effective porosity, so it reflects movement through connected pore spaces and is usually higher.
3. Should the head values use the same reference level?
Yes. Both heads must use the same datum and unit. The calculator uses their difference to determine hydraulic gradient and likely flow direction.
4. Can this tool be used for unconfined aquifers?
Yes, for screening estimates. However, strongly changing saturated thickness, recharge effects, and nonlinear behavior may require a more detailed groundwater model.
5. What porosity should I enter?
Use effective porosity rather than total porosity. Effective porosity represents the connected pore space available for groundwater movement.
6. Does the anisotropy factor replace field testing?
No. It is a quick adjustment for directional conductivity or field calibration. Pumping tests and site investigations remain more reliable for design decisions.
7. Why might travel time show as unavailable?
Travel time becomes unavailable when seepage velocity is zero. Check head difference, flow length, conductivity, porosity, and correction factor inputs.
8. Is this suitable for contaminant transport design?
It is useful for first-pass estimates. Detailed transport studies should also include dispersion, decay, sorption, heterogeneity, recharge, and boundary conditions.