Ground infiltration formula (Water Overlay): Difference between revisions

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First the height of the unsaturated zone is calculated.
First the height of the unsaturated zone is calculated.
: <math>d_{u} = B_{c} - WL_{underground}</math>
: <math>d_{u} = B_{c} - w_u</math>


Then the ratio of water amount to unsaturated height is calculated.
Then the ratio of water amount to unsaturated height is calculated.
: <math>r = W_{unsat}/d_{u}</math>
: <math>r = \Delta w_u/d_{u}</math>


Then calculate the distance of the unsaturated zone which can infiltrate.
Then calculate the distance of the unsaturated zone which can infiltrate.
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Finally, calculate the actual amount of water infiltrating.
Finally, calculate the actual amount of water infiltrating.
: <math>\Delta w = d_{i} \cdot r</math>
: <math>\Delta w_i = d_{i} \cdot r</math>


Where:
Where:
: <math>\Delta w</math> = The underground infiltration which takes place.
: <math>\Delta w_i</math> = The underground infiltration which takes place.
: <math>\Delta t</math> = Computational timestep.
: <math>\Delta t</math> = Computational timestep.


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: <math>d_{i}</math> = The height distance in the unsaturated zone which can be subject to infiltration to the saturated zone.
: <math>d_{i}</math> = The height distance in the unsaturated zone which can be subject to infiltration to the saturated zone.


: <math>W_{unset}</math> = The amount of water in the unsaturated zone. The height of the water column if the equivalent amount of water was placed on the surface.
: <math>\Delta w_u</math> = The amount of water in the unsaturated zone. The height of the water column if the equivalent amount of water was placed on the surface.
: <math>WL_{underground}</math> = The [[Groundwater level formula (Water Overlay)|groundwater level]], relative to {{datum}}.
: <math>w_u</math> = The [[Groundwater level formula (Water Overlay)|groundwater level]], relative to {{datum}}.
: <math>B_c</math> = the datum height of the surface of cell c, set by the [[Elevation (Water Overlay)|elevation]] or a [[Terrain elevation prequel (Water Overlay)|Terrain elevation prequel]].
: <math>B_c</math> = the datum height of the surface of cell c, set by the [[Elevation (Water Overlay)|elevation]] or a [[Terrain elevation prequel (Water Overlay)|Terrain elevation prequel]].
: <math>I_{u}</math> = The [[Terrain ground infiltration md (Water Overlay)|GROUND_INFILTRATION_MD]] of the underground terrain type.
: <math>I_{u}</math> = The [[Terrain ground infiltration md (Water Overlay)|GROUND_INFILTRATION_MD]] of the underground terrain type.

Revision as of 12:48, 25 January 2024

Underground infiltration (from the unsaturated zone to the saturated zone) is calculated per cell.

First the height of the unsaturated zone is calculated.

Then the ratio of water amount to unsaturated height is calculated.

Then calculate the distance of the unsaturated zone which can infiltrate.

Finally, calculate the actual amount of water infiltrating.

Where:

= The underground infiltration which takes place.
= Computational timestep.
= The height of the unsaturated zone.
= Ratio of water to height in the unsaturated zone.
= The height distance in the unsaturated zone which can be subject to infiltration to the saturated zone.
= The amount of water in the unsaturated zone. The height of the water column if the equivalent amount of water was placed on the surface.
= The groundwater level, relative to datum.
= the datum height of the surface of cell c, set by the elevation or a Terrain elevation prequel.
= The GROUND_INFILTRATION_MD of the underground terrain type.

Related

The following topics are related to this formula.

Formulas
Groundwater level formula
Surface infiltration formula
Underground seepage formula
Models
Underground model
Infiltration model
Tracer flow model