Experimental evaluation of infiltration using Holtan, Philip, and Mein and Larson equations

Abstract

Infiltration from constant rainfall intensity as predicted by the Philip, Holtan, and Mein and Larson models was compared to observed infiltration. Also, the effects of rainfall intensity and slope steepness on infiltration, for the conditions studied here, were investigated. The study was conducted at Atterbury Experimental Watershed on three small plots with slopes of 1 to 5 percent. The infiltration runs were made using a rainfall simulator. Three rainfall intensities were used (4.23, 8.07, 12.2 cm/hr). The parameters a and n involved in the Holtan equation were determined by regression analysis. In the Philip equation the value for the parameter k was set equal to the saturated hydraulic conductivity of the soils studied. The sorptivity term (s) was determined using nonlinear regression analysis. The parameters for the Mein and Larson model were determined using laboratory analysis. Using the parameters estimated in the above form, Holtan equation was the one that best reproduced the observed infiltration. No influence of slope on final infiltration rate was found. Rainfall intensity together with moisture content was found to have influence over the time to attain the final infiltration rate.