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

Revision as of 09:53, 10 July 2020

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

The seepage is calculated using the following formula: $Δ s = \frac{(h_{d} (t) - h_{x, y}}{c}$

Failed to parse (syntax error): {\displaystyle \delta s = \frac{(h_{d}(t) - h_{x,y}}{c} \cdot frac{Δt}{24*60*60}}

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

h_d(t) = h_c + h_v,t(t)

Finally, calculate the actual amount of water infiltrating.

Δw = Δs/ ws

Where:

Δs = The underground seepage which takes place, in meters.
Δt = Computational timestep in seconds.
h_d = ground water level (or head) of the external zone causing the seepage, in meters
h_{v> = additional variation in head of h_d over time}
c = resistance of the separating layer.
ws = soil water storage fraction

H_unsat = The height of the unsaturated zone.
S = Ratio of water to height in the unsaturated zone.
C_inf = The height in the unsaturated zone which can be subject to infiltration to the saturated zone.

W_unset = 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.
WL_underground = The groundwater level, relative to datum.
H_surface = The terrain height in the cell, relative to datum.
I_und = The GROUND_INFILTRATION_MD of the underground terrain type.

The following topics are related to this formula.

@@ Line 2: / Line 2: @@
 The seepage is calculated using the following formula:
-<math>\Delta s = \frac{a}{b}</math>
+<math>\Delta s = \frac{(h_{d}(t) - h_{x,y}}{c}</math>
-: <math>\delta s = frac{(h_{d}(t) - h_{x,y}}{c} \cdot frac{Δt}{24*60*60}</math>
+: <math>\delta s = \frac{(h_{d}(t) - h_{x,y}}{c} \cdot frac{Δt}{24*60*60}</math>
 The external seepage head is variable over time by the introduction of h<sub>v,t</sub>