Advances in Modeling Drip Irrigation - Review.

There has been a large number of studies carried out during the last two decades evaluating various aspects of drip irrigation using various empirical, analytical, and numerical models. Empirical models have typically been developed using a regression analysis of field observations and are used only to predict the dimensions of wetting patterns, which are important when designing optimal drip irrigation systems. On the other hand, analytical and numerical models usually solve governing flow equations for particular initial and boundary conditions, and the extent of their applications, especially of numerical models, is much wider. Several analytical solutions, developed by Philip (1984) to estimate a wetting perimeter for surface and subsurface drip irrigation, have been incorporated into an easy-to-use software WetUp (Cook et al., 2003). Numerical models are increasingly used, after their calibration, to evaluate many different aspects of various management practices of drip irrigation. These may include pulsing of irrigation, scheduling of irrigation, triggered irrigation, effects of plants, effects of back pressure and its potential compensation, combination of drip irrigation with mulching, and many other practices. I will review these applications and discuss numerical models used in these studies.