The effect of intermittent water application by surface point sources on the soil moisture dynamics and on deep percolation under the root zone

Abstract

The effect of intermittent water application by surface point sources on the soil moisture dynamics and on the water losses by deep percolation under the root zone was studied through the use of a cylindrical flow model which incorporates evaporation from the soil surface and water extraction by roots. Several combinations of discharge rate and irrigation durations were tested. The implementation of the mathematical model took place against two of the twelve USDA soil classes. One hour interval was used for the simulation of pulse trickle irrigation. Water content profiles are presented for a radial distance of 1, 17 and 32.8 cm from the point source and for various times. The results show that, for the same soil, for time equal to each time irrigation duration, the vertical component of the wetting front is greater for the smaller discharge rate than for the higher one. However, this difference was practically eliminated at the total simulation time which was defined as the time needed to reach the initial average water content in the root zone.