In this study, wetting front or wetted bulb coordinates in soil under surface trickle irrigation were measured for 1 loam soil and 2 sandy loam soils with 2 different emitter discharges of 2 and 4 L h-1 by using the trenching method. A model is presented for estimating wetted bulb coordinates with a function of emitter discharge, water application time, average variation in volumetric water content, and saturated hydraulic conductivity of soil. For calculating the distance of the maximum wet surface, relationships are presented based on saturated hydraulic conductivity and water application time. By comparison of measured values of wetting front coordinates, the presented model shows good reliability. The goodness of fit ratio and root mean square error of the model were 0.82 and 17.85 mm, respectively. The model for predicting surface trickle irrigation wetting front coordinates can be applicable for the emitter with 2 and 4 L h-1 discharges.

In this study, wetting front or wetted bulb coordinates in soil under surface trickle irrigation were measured for 1 loam soil and 2 sandy loam soils with 2 different emitter discharges of 2 and 4 L h-1 by using the trenching method. A model is presented for estimating wetted bulb coordinates with a function of emitter discharge, water application time, average variation in volumetric water content, and saturated hydraulic conductivity of soil. For calculating the distance of the maximum wet surface, relationships are presented based on saturated hydraulic conductivity and water application time. By comparison of measured values of wetting front coordinates, the presented model shows good reliability. The goodness of fit ratio and root mean square error of the model were 0.82 and 17.85 mm, respectively. The model for predicting surface trickle irrigation wetting front coordinates can be applicable for the emitter with 2 and 4 L h-1 discharges.