Table C-5. Threshold values for comparators controlling on-off switches on water flows of Water
Model (Model in Figure 14).



 Value
 Threshold Description Conditions acre ft

 Moisture equivalent volume of soil-substratea primitive and present 7.2x105

Total surface water capacity to lowest points on rimsb primitive 7.5x10
 present 3.5x10

Soil-substrate saturation volume to 8 ft depthc primitive and present 3.84x106

Volume capacity of lowest 2 ft of substrate primitive and present 9.6x105
Limit on evapotranspiration from surface water primitive and present 0

a(2.4xlO6 acres) x 5 ft x 0.06 = 7.2x105 acre ft

NOTE: Total land area is 2.4x106 acres. Estimated average depth of soil is 5 ft. Estimated moisture
equivalent of fine sand is 0.06 (Meinzer, 1942).
bEstimated values. Value for primitive conditions is the volume capacity of all ponds plus approximately
one-half the total volume capacity of major depressions (sloughs, strands, and swamp hammocks). Value
for present conditions is slightly less than one-half value for primitive conditions.
c(2.4xl06 acres) x 8 ft x 0.2 = 3.84x106 acre ft
NOTE: Total land area is 2.4x106 acres. Average porosity of substrate is 0.2 (Parker et al., 1955).
d(2.4x106 acres) x 2 ft x 0.2 = 9.6x105 acre ft