L = a (A /Awmax )b (13)



where a in the predrainage case is the perimeter of all

natural flow ways and in the present case is double the

length of all primary and secondary canals AW is surface

water area, AWmax is total wetlands area, and b is a number

between 1 and 2 that roughly relates width of the flow line

to water surface area. A /Awmax was less than 1 when

wetlands were not filled, equal to 1 when wetlands were

covered, and greater than 1 when uplands were flooded. The

maximum possible value of (A /Amax )b was 2. This allowed

for increased importance of connected shallow ditches for

removal of surface water when upland areas were flooded.

 Evapotranspiration from surface water. The equation

for evapotranspiration from surface water in the model was:


 Ew = 0.75 S Pe AW (14)



where Pe is long term average pan evaporation for each

month of the year, measured at Royal Palm Ranger Station in

the Everglades (U. S. Department of Commerce. National

Oceanic and Atmospheric Administration. 1974), AW is

surface water area, and S is a coefficient of plant

activity and shading that increases or decreases

evapotranspiration seasonally in correlation with leaf

senescence and regrowth of predominant vegetation cover.

This equation goes to zero as AW goes to zero.