Ground bottom flow formula (Water Overlay): Difference between revisions

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Underground seepage (from (or to) outside the project area) is calculated per cell.
Underground seepage (from (or to) outside the project area) is calculated per cell.


The seepage is calculated using the following formula:
The water level change due to seepage is calculated using the following formula:
: <math>\Delta s = \frac{h_{d}(t) - h_{x,y}}{c_{x,y}} \cdot \frac{\Delta t}{24 \cdot 60 \cdot 60}</math>
: <math>\Delta s = \frac{h_{d}(t) - h_{x,y}}{c_{x,y}} \cdot \frac{\Delta t}{24 \cdot 60 \cdot 60}</math>


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Finally, calculate the actual amount of water seeping into (or out of) the ground from the bottom.
Finally, calculate the actual amount of water seeping into (or out of) the ground from the bottom.
: <math>\Delta w = {\Delta s}\cdot{ws}</math>
: <math>\Delta w_{x,y} = {\Delta s}\cdot{ws}</math>


Where:
Where:
* <math>\Delta s</math> = The underground seepage which takes place, in meters.
* <math>\Delta s</math> = The water level change due to seepage, in meters.
* <math>\Delta t</math> = Computational timestep in seconds.
* <math>\Delta t</math> = Computational timestep in seconds.
* <math>h_{x,y}</math> = Ground water head in the grid cell.
* <math>h_{x,y}</math> = Ground water head in the grid cell.
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* <math>c</math> = resistance of the separating layer in days
* <math>c</math> = resistance of the separating layer in days
* <math>ws</math> = water storage fraction of the soil
* <math>ws</math> = water storage fraction of the soil
* <math>\Delta w</math> = seeped in water in m


==Notes==
==Notes==

Revision as of 08:55, 28 August 2020

Underground seepage (from (or to) outside the project area) is calculated per cell.

The water level change due to seepage is calculated using the following formula:

The external seepage head is variable over time by the introduction of hv,t

Finally, calculate the actual amount of water seeping into (or out of) the ground from the bottom.

Where:

  • = The water level change due to seepage, in meters.
  • = Computational timestep in seconds.
  • = Ground water head in the grid cell.
  • = additional ground water level (or head) of the external zone causing the seepage at time t, in meters
  • = constant ground water level (or head) of the external zone causing the seepage, in meters
  • = additional variation of seepage head over time
  • = resistance of the separating layer in days
  • = water storage fraction of the soil
  • = seeped in water in m

Notes

  • and can both be provided as spatially variable values.
  • can be provided as a set of values, variable over time.

See also

Water Module
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Water Module
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Tutorials
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Overview
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Theory
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Benchmarks
Models
Surface • Ground • Rain • Evaporation • Infiltration • Elevation • Breach • Sewer • Storage • Tracer flow • Border • Order
Model formulas
Timestep • Season • Surface water level • Groundwater level
Flow formulas
Surface flow • Surface infiltration • Ground flow • Ground infiltration • Surface evaporation • Ground evaporation • Ground bottom flow
Hydraulic structure formulas
Culvert • Weir • Breach growth • Breach flow • Pump • Sewer Overflow • Inlet • Drainage
Related
Building attributes • Hydrological features • Hydraulic structures •  Terrain attributes • Model attributes • Results • Simulation data
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