Time Series Application to Model and Forecast Wetted Soil Volume from a Point Source Emitter

The wetted soil volume (WSV) is the most important principle in drip irrigation designing which is applied to determine irrigation intervals of raw crops. Therefore and based on time series techniques ability in modeling and forecasting of hydrological phenomena، a set experiments were conducted at East Azarbaijan Research Center for Agriculture and Natural Resources، Tabriz، Iran with the aim of time series modeling and forecasting of WSV from a point source. The point source discharges were selected as 2، 4 and 8 Lh-1 and WSV were estimated based on vertical and horizontal advance of moisture. Also، wetted soil volumes were estimated for several times. Results showed that WSV had non-stationary behavior during 210 min. Differencing natural logarithm of WSV data were applied to make stationary behavior for WES data. Accordingly، to describe WSV from point sources، ARIMA (1، 1، 0) was recognized as a suitable time series model. Based on achieved model، WSV series were forecasted as 38، 164 and 223×1000 cm3 for the next 90 min (from 210 to 300 min). It is recommended that ARIMA (1،1،0) can be applied to model and forecast wetted soil volume in similar soil condition.