Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

Hydraulic gradient, abbreviated as i, a dimensionless number, is the change in height (pressure) to length between any two points.

 $$\large{ i = \frac{ Q }{ k \; A_c } }$$

### Where:

 Units English Metric $$\large{ i }$$ = hydraulic gradient $$\large{dimensionless}$$ $$\large{ A_c }$$ = area cross-section $$\large{ft^2}$$ $$\large{m^2}$$ $$\large{ Q }$$ = flow rate $$\large{\frac{ft^3}{sec}}$$ $$\large{\frac{m^3}{s}}$$ $$\large{ k }$$ = hydraulic conductivity $$\large{\frac{ft}{day}}$$ $$\large{\frac{m}{day}}$$

 $$\large{ i = \frac{v}{k} }$$ (Darcy velocity)
$$\large{ i }$$ = hydraulic gradient
$$\large{ v }$$ = Darcy velocity or flux