Hydraulic Gradient Calculator
Reviewed by Hamza Gujjar, Algorithm Architect & Software Developer
Last updated: July 27, 2026What drives groundwater to flow
Groundwater does not flow because of pressure differences alone - it flows because of differences in hydraulic head over distance, expressed as a dimensionless slope called hydraulic gradient.
Worked example
For a 2-meter head difference measured over a 100-meter flow path:
i = 2 / 100 = 0.02
Hydraulic gradient is the "i" term in Darcy's Law (v = K x i), meaning this figure is a required input for calculating actual groundwater flow velocity once combined with a soil or rock formation's hydraulic conductivity.
In the field, hydraulic gradient is typically measured using two or more monitoring wells, comparing the water table elevation (head) between them relative to the horizontal distance separating the wells.