Water Model

 A diagrammatic representation of the model of water

volume and surface water area is shown in Figure 14.

Compartments of water storage are soil (includes ground)

and surface. Rainfall is channeled into the soil unless

this compartment is full (saturated), in which case it is

shunted directly into surface storage. Land surface area

covered by water is proportional to the volume of surface

water, according to the area-volume curve developed in this

study. Dry land area is total land area with wetlands area

subtracted from it. Water is removed from the soil and

aquifer by groundwater flow at a rate determined by the

gradient between the water table and sea level and by soil

and aquifer permeability characteristics. The water of

low-lying areas is augmented by runoff from surrounding

higher land. Input is by surface flow during the rainy

season and by horizontal flow through the ground during the

dry season. Under some conditions (i. e. when ground or

soil water level is lower than surface water level) surface

water sources restock soil water supplies. Overland flow

does not occur until surface storage areas are filled to

the lowest points on their rims. Surface water and soil

water are.subjected to evapotranspiration (ET), which is

greater during warm weather months than in winter because

of differences in wind and temperature, and also because of

seasonal physiological changes in predominant plants. In

areas where there is no standing water, ET is proportional