Abstract

Due to the decreasing availability of water resources and the increasing competition for water between different users, improving agricultural water use efficiency is vitally important in many parts of the world that have limited water resources. In designing trickle irrigation systems, the dimension of the wetted volume is one of the main factors in determining the spacing of drippers. This study was designated to experimentally determine the dimensions of wetted soil volume beneath the dripper for three different soil types (clay, clay-loam, sandy loam) and four water application rates (2,4,8,12 Lh^-1) in a sand-box physical model. The parameters affected the wetted soil volume of vertical wetting front advance Zf, lateral wetting front advance within the soil profile Xf and Yf, were researched. These parameters were predicted with empirical equations. The results were compared to the measured data. The results showed the empirical equations have different performances in the studied soils. Based on our experiment, these equations can be used as a reliable method to predict the volume of wetted soil in design of trickle irrigation systems especially in loamy soils.

Key words: Emitter, infiltration, irrigation, point source, wetted soil, wetting front.