Ground infiltration formula (Water Overlay): Difference between revisions

Revision as of 12:49, 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.

d_{u}=B_{c}-w_{g}

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

r=\Delta w_{u}/d_{u}

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

d_{i}=min(d_{u},\Delta t\cdot I_{g})

Finally, calculate the actual amount of water infiltrating.

\Delta w_{i}=d_{i}\cdot r

Where:

w_{g}

B_{c}

= the datum height of the surface of cell c, set by the elevation or a Terrain elevation prequel.

d_{u}

= The height of the unsaturated zone.

\Delta w_{u}

= 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.

r

= Ratio of water to height in the unsaturated zone.

\Delta t

= Computational timestep.

I_{g}

= The GROUND_INFILTRATION_MD of the underground terrain type.

d_{i}

= The height distance in the unsaturated zone which can be subject to infiltration to the saturated zone.

\Delta w_{i}

= The underground infiltration which takes place.

@@ Line 8: / Line 8: @@
 Then calculate the distance of the unsaturated zone which can infiltrate.
-: <math>d_{i} = min( d_{u} , \Delta t \cdot I_{u} )</math>
+: <math>d_{i} = min( d_{u} , \Delta t \cdot I_{g} )</math>
 Finally, calculate the actual amount of water infiltrating.
@@ Line 20: / Line 20: @@
 : <math>r</math> = Ratio of water to height in the unsaturated zone.
 : <math>\Delta t</math> = Computational timestep.
-: <math>I_{u}</math> = The [[Terrain ground infiltration md (Water Overlay)|GROUND_INFILTRATION_MD]] of the underground terrain type.
+: <math>I_{g}</math> = The [[Terrain ground infiltration md (Water Overlay)|GROUND_INFILTRATION_MD]] of the underground terrain type.
 : <math>d_{i}</math> = The height distance in the unsaturated zone which can be subject to infiltration to the saturated zone.
 : <math>\Delta w_i</math> = The underground infiltration which takes place.