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

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: <math>\Delta wl_{x,y} = \frac{h_{d}(t) - h_{x,y}}{c_{x,y}} \cdot \frac{\Delta t}{24 \cdot 60 \cdot 60}</math>
: <math>\Delta wl_{x,y} = \frac{h_{d}(t) - h_{x,y}}{c_{x,y}} \cdot \frac{\Delta t}{24 \cdot 60 \cdot 60}</math>


The external seepage head is variable over time by the introduction of h<sub>v,t</sub>:
The external seepage head is variable over time by the introduction of <math>h_{v}(t)</math>:
: <math>h_d(t) = h_{p_{x,y}} + h_{v}(t)</math>
: <math>h_d(t) = h_{p_{x,y}} + h_{v}(t)</math>



Revision as of 13:54, 7 September 2020

Underground seepage from outside the project area is calculated per grid cell. The formula is based on the formula of Pankow for estimating seepage[1].

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 :

Finally, the actual amount of water seeping into the ground from the bottom is calculated as followed:

Where:

Notes

  • The calculated is essentially the change in groundwater level, inherently taking into account the porosity of the soil. The final is representative of the actual amount of water, i.e. the height of the water, if the relevant quantity of water wasn't in the underground but sat on the surface instead.
  • and can both be provided as spatially variable values.
  • can be provided as a set of values, variable over time.
  • A seepage head lower than the water level in the project is also allowed, resulting in water seeping out to a region outside the project area.

Related

The following topics are related to this formula.

Formulas
Groundwater level formula
Models
Underground model

See also

References