Recharge

Recharge is defined as the sum of all the flows to or from the water table aquifer, including percolation, evapotranspiration, irrigation withdrawals, canal interaction, and levee seepage. The Recharge term calculated in ET/Recharge program is not used by South Florida Water Management Model (SFWMM). The recharge term, RCHG, in the SFWMM simulation of the Lower East Coast Developed Areas is calculated by:

RCHG = RCHG + PERC - NIRRSUPTOT; - PWSSUP - ETS,

where PERC is the percolation volume from unsaturated zone to water table aquifer, UT are the usage type (urban landscape, nursery golf course, agricultural low volume, agricultural high volume, and other agricultural. UT NIRRSUP (UT) is the sum of the net irrigation demand volumes for the six usage type, PWSSUP is the public water supply withdrawal at the well, and ETS is the evapotranspiration volume from the water table (for non-irrigated areas of Lower East Coast cells).

Although not applicable to the SFWMM. Recharge also varies by surface type. For a Free Water Surface,

Recharge (Free Water Surface) = Rainfall.

For Impervious Areas,

Recharge (Impervious Areas) = F,

where F is the total infiltration and is calculated by

F = Rainfall - Runoff - IR,

where IR is the initial surface retention consisting of interception and evaporation from depression storage and depends mainly on land use type, simulated as a constant for impervious and pervious land use surfaces.

For Pervious Areas,

Recharge(Pervious Areas) = value computed by AFSIRS model..

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