PONDED INFILTRATION INTO SIMPLE SOIL SYSTEMS

Abstract

Experimental results reported earlier (Bond and Collis-George 1981) are used to examine the behavior of infiltration rate with time during ponded infiltration into simple soil systems. The apparent linearity of a measured cumulative infiltration-time relationship is shown not to be a reliable indicator of steady state. An equation based on Darcy's law, relating the infiltration rate to the total potential gradient in the transmission zone, is derived and experimentally tested. This equation is used to show that steady-state infiltration cannot be expected to be attained in finite time during infiltration into simple soil systems. In addition, the equation is used to illustrate the effect of the saturation and transition zones on the infiltration rate and, consequently, the errors arising from infiltration models that neglect the existence of these zones. Experimental results reported earlier (Bond and Collis-George 1981) are used to examine the behavior of infiltration rate with time during ponded infiltration into simple soil systems. The apparent linearity of a measured cumulative infiltration-time relationship is shown not to be a reliable indicator of steady state. An equation based on Darcy's law, relating the infiltration rate to the total potential gradient in the transmission zone, is derived and experimentally tested. This equation is used to show that steady-state infiltration cannot be expected to be attained in finite time during infiltration into simple soil systems. In addition, the equation is used to illustrate the effect of the saturation and transition zones on the infiltration rate and, consequently, the errors arising from infiltration models that neglect the existence of these zones. © Williams & Wilkins 1981. All Rights Reserved.