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The Irrigator model calculates a list of regulated and opportunistic irrigation requirements between now and the maximum travel time. This requires that soil depletion, as defined by the soil water balance (Equation 1), is forecasted from the current time-step to the maximum travel time. This requires forecasts of evapotranspiration, rainfall, deep percolation, runoff and water that has been previously orderedwill be ordered. If an opportunistic target is not configured, the forecast soil depletion is supplemented by the forecast water ordered to meet the regulated target. If an opportunistic target is configured, the crop assumed it is going to receive the opportunistic volume ordered, so the forecast soil depletion is supplemented by the forecast water ordered to meet the opportunistic target - noting this is still capped by water available.
Forecast values of P and ETo are required to estimate soil depletion into the future. Two options for forecasting ETo and rainfall. The user can specify an average daily pattern, which represents long term average ETo and rainfall on each day of the year. Alternatively, you can specify the number of previous time-steps, and the model calculates the forecast ETo and rainfall by averaging the previous specified number time-steps.
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