DIFFERENT APPROACHES TO ESTIMATE THE SUCTION HEAD AT THE WET FRONT IN THE GREEN AND AMPT WATER INFILTRATION EQUATION
Main Article Content
Abstract
This study was conducted to estimate the suction head at the wetting front T in the Green and Ampt infiltration equation using uniformly packed soil columns of three different - textured soils. Four different approaches were used for this estimation. Cumulative depths of infiltration I along with the visual wet front advance Z was recorded with time t. Soil water content profiles were also obtained by which the sharpness of the wet front was tested using an empirical model adopted from van Genuchten (1980) model for soil moisture-suction head relation. The Green and Ampt equation did fit the infiltration data very well with significant correlation of its parameter K with the physical measure of saturated hydraulic conductivity K. Four different methods were used to estimate t: from fitting the Green and Ampt cquation to infiltration data (I vs. t), numerical integration using hydraulic conductivity as afunction of suctionhead K() in the basic definition equation of defining t, numerical integration using conductivity as afunction of volumetric water content K(0), and from the soil sorptivity S evaluated from early time infiltration data using Philip one-term equation alons with Green and Ampt equation for horizontal infiltration No significant differences were found between these four methods in estimating t at 0.01 level. Significant differences, however, were found at the same level between the values of T for the three soils as it was expected.
Article Details
Section
How to Cite
References
Aggelides, S. and E. G. Youngs. (1978), The dependence of the parameters in the Green and Ampt infiltration equation on the initial water content in draining and wetting states. Water Resource. Res. 14: 857-862
Ahuja, L. R. (1983), Modelling infiltration into crusted soils by the Green and Ampt approach. Soil Sci. Soc. Am. J. 47: 412-418.
Al-Duri, N. T. (2002), Assessment of Water transport Functions for Soil Treated with Fuel Oil. Ph.D. Thesis. College of Agriculture. University of Baghdad
Aoda, M. I (1992), Application of the Green and Ampt to water infiltration under trickle irrigation. Basrah J. Agric. Sci. 5(2):169-177.
Aodn, M. I and D. Swartrendruber. (1987) Critical assessernent of the Green ind Ampt water infiltration equation 1. Theoretical analysis. Iragi J. Agric. Sci. "ZANCO" 5(4): 59-69 Bouwer, H. (1969), Infiltration of water into nonuniform soil. J. Imig. Drain. Div. Am. Soc. Civil Engn. 95: 451-462. Boawer, H. (1976), Intiltration into increasingly permeable soils. J. Irrig Drain. Div. Am. Soc. Civil Enm 102: 127-136 Bralcensick, D. L and C. A. Onstad. (1977), Parameter estimation of the Green and Amp infiltration equation. Water Resou. Res 13:680-682
Childs, E. G. (1967), Soil moisture theory. Advan. Hydro. Sci. 4: 73-117 Childs, E. G., and M. Bybordi. (1969) The vertieal movement of water in stratified porous material. I. Infiltration. Water Resou Res, 3:446-459.
Chu, S. T. (1978), Infiltrations during unsteady rain. Water Resour. Res. 14: 461-466.
Collis-George, W. (1980), Apragmatic method to determinte the paraneters that characterize
ponded infiltration. Aut. J. Soil Res. 18:111-117. Darcy, H. (1856), Les fontains publique de laville de Dijon. Voetor Dalmont, Paris Gardner, W. H (1967), Development of modern infiltration theory and its application in hydrology Ed. J.C. Rodda. 199.227, John wiley and Sons. New York Green, W. H. and G. A. Ampt. 1911. Studies on soil physics. 1. Flow of water and air through soils
J.Agrie. Sci. 4:1-24.
Hillel, D. and W. R. Gardner (1970) Transient infiltration into crust-topped profiles. Soil Sci 109:69-76
James, L. G. and C. L. Larson 1976. Modeling infiltration and redistribution of soil water during
intermittent application. Trans. Am Soc Agrie. Engn 19:482-488
Klute. A. (965), Lab conductivity of saturated soil. In Black, C Aet ptalory measurment of hydruli of soil analysis. Agron. Mono, No. 91): 253-261. Am. Soc Agron Madison, Wisconsin, USA. Koorevaar, P G. Monelik and C. Dirksen (1983) Elements of soil physics. Elsevier Seience
publishing B. v., Amsterdam. Pp. 158
Mein, R. G. and C. L. Larson. (1973), Modling infiltration during steady rain. Water Resource. Res 9: 384-304 Miller R. D. and EA. Bresler, (1977) A quick method for estimnting soil water dinlusivity. Soil Sel Soc. AnJ 4 1020-1022
Neuman, S. P. (1976), Wetting front pressure need in the infiltration model of Green and Ampt. Water Resour. Res. 12: 564-567.
Panikar, J. T. and G. Nangappa. (1977), Suction head at the wet front in unsaturated flow. Problem
a new definition. J. Hydrol. 33: 1-14.
Philip. J. R. (1954), An infiltration equation with physical significant. Soil Sci. 77: 153-157 Philip, J.R. (1958), The theory of infiltration: 7. Soil Sei. 85:333-337
Rawls, W.J. and D. L. Brakensiek. (1983). A procedure to predict Green and Ampt infiltration parameters. Proceeding of the Am. Soc. Agrie Engn. Conference on advances in Infiltration. Am
Soe. Agric. Engn. St. Joeseph, MI. Pp: 102-112. Cary, NC. USA.
SAS Institute. 1990. SAS/STAT User's guide, Version 6.06 ed. SAS Inst.
Swartzendruber, D. (1974), Infiltration of constant-flux rainfall into soil as analyzed by the approach of Green and Ampt. Soil Sci. 117:272-281
Van Genuchten, M. Th. (1980), A closed- from equation for predicting the hydraulie conductivity of unsaturated soil. Soil Sci. Soc. Am. J. 44:892.298
Whisler, F. D. and A. Bouwer. (1970), Comparison method for calculating vertical drainage and infiltration for soils. J. Hydrol. 10: 1-19.
Youngs, E. G. (1972). Two-and three-dimensional infiltration: seepage from irrigation channels and infiltrometer rings. J. Hydrol. 15:301-315
Zhang, G. J. Yuan and B. Liu. (1999), Determining absorptive parumeter S in Green and Ampt model based on unsaturated soil physicai properties. Proceeding of 99 International conference on Agricultural Engineering. Beijing: China. Dec. 1999. I1: 233-237