**2.4.1 Presaturation irrigation requirements**

A huge amount of water is consumed to inundate fields for presaturation before planting of the crop. The water required during presaturation period can be determined as follows:

$$\text{SAT} = \frac{\text{IR}\_{\text{LS}} + \text{EP}\_{\text{S}} + \text{SP} + \text{SW}}{\text{IE}} \tag{1}$$

Where,

SAT = water requirement during presaturation period (mm/day) IRLS = water requirement to saturate the soil (mm/day) EPs = evaporation loss from saturated soil surface (mm/day) SP = seepage and percolation losses (mm/day) SW = additional supply to maintain the initial depth of flooding (mm/day) IE = overall irrigation efficiency
