Infiltration

Infiltration in non-irrigated areas simulates the transfer of water from ponding to the saturated zone in some areas, illustrated in Figure 11. The infiltration rate and soil storage coefficient of the soil cover basin are used to calculate the water available to infiltrate, the water stored in the unsaturated zone in the cell, and the potential infiltration. Infiltration is the minimum of these three calculations.

Total ifiltration, F or Recharge, is computed by

F = Rain - Runoff - IR,

where IF is the initial infiltration before runoff and IR is the initial surface retention consisting of interception and evaporation from depression storage. The model sets IR to a constant value dependent on land surface type. For Impervious Areas,

IR(Impervious Areas) = 0.07 inches and

IF(Impervious Areas = 0.0 inches.

For Pervious Areas,

IR(IPervious Areas) = 0.25 inches and 0.10 in for CN > 75

IF (Pervious Areas) = 0.18 in for 50 <= CN <= 75

0.28 for CN < 50

where CN is the Soil Conservation Service runoff curve number tabulated using modified tables for South Florida Conditions (see section on Runoff for more detail).

Figure 11. Infiltration in SFWMM and NSM

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