New empirical model for wetted dimensions prediction in soil under drip irrigation

Reliable information about wetted dimensions in drip irrigation helps designers to select best emitter spacing and reduce system equipment costs, and provide better condition for effective use of water as a main problem in Iran agriculture. In this study we present the new empirical formula which its coefficients were obtained from results of field experiments, which was done in Pardis Agricultural farm of Tehran University in Karaj. The coefficient of this equation determined with optimization with less square approach. Also we used these data to evaluate semi-empirical model of Zur-Schwartzman. The evaluation of models based on comparison of statistical parameters of simulated data with that observed data. The parameters used were Mean Error (ME), Root Mean Square Error (RMSE) and model efficiency (EF). Acceptable agreement between theoretical and experimental results improves the validity of these equations. To evaluate above mentioned models also two available published experimental data by Risse et al. (1989) and Li et al. (2004) was used. The results show that suggested equations can be used for wider range of discharge rate and other soil types. The best result in this investigation was obtained from empirical model which were presented in this study. The lowest mean error for wetted radius is equal to 7.95 and the lowest mean error for wetted depth is equal to 8.64.

Keywords:

drip irrigation , wetted dimension , empirical models