**Figure 2.**
Soil reservoirs with hydrological inflow and outflow components. Note:

P_{p} is the amount of water vertically reaching the soil surface, such as precipitation and sprinkler irrigation;

I_{i} is the irrigation water supplied by the canal system;

I_{g} is the gross irrigation inflow including the natural surface inflow and the drain and well water used for irrigation, but excluding the percolation losses from the canal system;

I_{0} is the amount of irrigation water leaving the area through the canal system (bypass);

E_{o} is the amount of evaporation from open water;

E_{ra} is the amount of actual evapotranspiration from the root zone; λ

_{i} is the amount of water infiltrated through the soil surface into the root zone; λ

_{0} is the amount of water ex-filtrated through the soil surface from the root zone; the term λ

_{0} is not shown in

Figure 2 as it can occur only when the water table is above the soil surface; S

_{o} is the amount of surface runoff or surface drainage leaving the area;

L_{c} is the percolation loss from the irrigation canal system;

L_{r} is the amount of percolation losses from the root zone;

V_{R} is the amount of vertical upward seepage from the aquifer into the transition zone;

V_{L} is the amount of vertical downward drainage from the saturated transition zone to the aquifer;

R_{r} is the amount of capillary rise into the root zone;

G_{w} is the amount ground water pumped from the aquifer through wells;

G_{d} is the total amount of subsurface drainage water;

G_{i} and

G_{o} are the horizontally incoming/outgoing ground water flow into a polygon through the aquifer;

F_{w} is the fraction of the pumped well water

G_{w} used for irrigation and

G_{u} is the quantity of subsurface drainage water used for irrigation.

F_{w}G_{w} and

G_{u} were negligible and were set equal to zero in this study. ΔW

_{s} is the change in the amount of water stored in the surface reservoir.