How to use the groundwater recharge water balance calculator
Estimate groundwater recharge from precipitation, evapotranspiration and surface runoff. Enter precipitation, evapotranspiration, surface runoff in the fields above; the groundwater recharge, recharge as share of rain are computed instantly and plotted on the chart so you can see how the answer changes.
Common searches this calculator answers include “groundwater recharge”, “water balance equation”, “how much rain recharges aquifer”, “calculate groundwater recharge water balance”, “find groundwater recharge”.
Formula
Variables
- P — Precipitation (mm/year)
- ET — Evapotranspiration (mm/year)
- RO — Surface runoff (mm/year)
Worked example
With precipitation = 900 mm/year, evapotranspiration = 600 mm/year, surface runoff = 150 mm/year, the calculator gives groundwater recharge ≈ 150 mm/year; recharge as share of rain ≈ 16.66667 %.
Frequently asked questions
What is the groundwater recharge water balance calculator used for?
Estimate groundwater recharge from precipitation, evapotranspiration and surface runoff. It helps with questions such as “groundwater recharge”, “water balance equation”, “how much rain recharges aquifer”.
What is the formula for the groundwater recharge water balance calculation?
Groundwater recharge (mm/year) = P-ET-RO. Recharge as share of rain (%) = [Groundwater recharge] / P × 100. Here P is precipitation (mm/year), ET is evapotranspiration (mm/year), RO is surface runoff (mm/year).
What inputs do I need for the groundwater recharge water balance calculator?
You need precipitation in mm/year, evapotranspiration in mm/year, surface runoff in mm/year. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use the groundwater recharge water balance calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the groundwater recharge water balance result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.