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Estimating wetting front coordinates under surface trickle irrigation

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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. | Research Article Turk J Agric For 36 (2012) 729-737 © TÜBİTAK doi:10.3906/tar-1202-74 Estimating wetting front coordinates under surface trickle irrigation Ahad MOLAVI1,*, Aliashraf SADRADDINI2, Amir Hossein NAZEMI2, Ahmad FAKHERI FARD2 1 Department of Soil and Water Sciences, Tabriz Branch, Islamic Azad University, Tabriz – IRAN 2 Department of Water Engineering, Faculty of Agriculture, Tabriz University, Tabriz – IRAN Received: 28.02.2012 ● Accepted: 30.04.2012 Abstract: 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. Key words: Incomplete sphere, saturated hydraulic conductivity, wetted bulb, wetting front coordinates Introduction Trickle irrigation is considered to be an appropriate method for areas of limited water resources due to high efficiency of water use under good management. For design and management of a trickle irrigation system, the shape of the wetted bulb should be known, and it can be predicted by solving numerical equations governing flow (Bristow et al. 2000). One of the basic factors in the design of trickle irrigation systems is the .