# Groundwater level formula (Water Overlay)

Groundwater level is calculated per cell.

${\displaystyle h_{u}={\frac {\Delta w_{s}}{sp}}}$
${\displaystyle gl_{u}=h_{u}+B-d_{b}}$

Where:

• ${\displaystyle h_{u}}$ = The height (column) of the saturated zone.
• ${\displaystyle \Delta w_{s}}$ = The amount of water in the saturated zone. The height of the water column if the equivalent amount of water was placed on the surface.
• ${\displaystyle sp}$ = The WATER_STORAGE_PERCENTAGE of the underground terrain type, used here as a fraction.
• ${\displaystyle gl_{u}}$ = The groundwater level, relative to datum. Also known as the watertable.
• ${\displaystyle B}$ = The surface height in the cell, relative to datum.
• ${\displaystyle d_{b}}$ = The GROUND_BOTTOM_DISTANCE_M (effectively available height in the underground model).

## Related

The following topics are related to this formula.

Features
Groundwater
Formulas
Underground flow formula
Underground evaporation formula
Surface infiltration formula
Underground infiltration formula
Underground seepage formula
Models
Surface model
Underground model
Evaporation model
Infiltration model