INTRODUCTION
Understanding of irrigation-induced infiltration and characteristics of soil water movement are fundamental to efficient management of water resources, especially for those of arid and semi-arid regions where water is scarce and crop production is critical for economic development. It is also the basis of consideration in the design, evaluation, and management of an irrigation system (Zerihun et al., 1996; Oyonarte et al., 2002). Infiltration characteristics, particularly infiltrability of cropland directly affect irrigation scheduling and water use efficiency; hence the performance of an irrigation system is strongly influenced by infiltration.
Nevertheless, these processes are much more complex than those in saturated zones, since they are involved with multiphase flow processes such as gravity- and capillary-driven moisture flow (Doughty, 1999). Despite the complexity of soil water infiltration, its impacting factors can be aggregated into two main aspects, namely soil physical properties and the time and amount of water applied (Shainberg and Singer, 1985; Shainberg et al., 1991), the latter of which actually is associated with irrigation methods and scheduling.
Numerical simulation is an ideal tool to investigate the processes of irrigation induced water infiltration and to assess the performance of various irrigation schedules, by looking into the dynamics of wetting front and the resulting distribution of SWC. The present study focuses on simulating infiltration physics and analyzing its potential influencing factors, to shed light on the design of irrigation systems that improve the efficiency of water use. This is of significance especially for those areas where the sustainability of the irrigated agriculture is at serious risk.