Hydraulic conductivity and sorptivity at unsaturated and saturated conditions as related to water infiltration in soils

Authors : Abdelmonem Mohamed Ahmed AMER

Pages : 1-9

Doi:10.18393/ejss.621759

View : 62 | Download : 8

Publication Date : 2020-01-01

Article Type : Research Paper

Abstract :Sorptivity insert ignore into journalissuearticles values(S); has been defined in terms of the horizontal infiltration equation. At unsaturated conditions insert ignore into journalissuearticles values(at a very short time); S represents “maximum sorption capacity”, but in saturated conditions the sorption capacity decreases with the time. Over a long time of infiltration, sorptivity was not studied as a soil water parameter that could be determined. The purpose of this study is to apply derived equations depending on the infiltration functions to predict insert ignore into journalissuearticles values(1); soil water sorptivity insert ignore into journalissuearticles values(S); at infiltration capacity insert ignore into journalissuearticles values( unsaturated conditions ); and at basic infiltration rate insert ignore into journalissuearticles values(I b ); insert ignore into journalissuearticles values( saturated conditions );, insert ignore into journalissuearticles values(2); the hydraulic conductivity insert ignore into journalissuearticles values(Saturated Ks and unsaturated K insert ignore into journalissuearticles values(θ ); ); into capillary-matrix and non-capillary macro pores of soils.  Five alluvial insert ignore into journalissuearticles values(saline and non-saline clay); and calcareous soil profiles located in the Nile Delta were investigated for applying the assumed equations. A decrease in S value was observed with an increase in soil water content. At steady infiltration rate insert ignore into journalissuearticles values(I b );, S decreased from 1.04 to 0.647cm.min -0.5 insert ignore into journalissuearticles values(i.e. S decreased by 37.79%); in average in calcareous soils and from 0.537 to 0.251cm.min -0.5 insert ignore into journalissuearticles values(53.25%); in alluvial clay soils. The steady S w parameter was used in prediction of the hydraulic conductivities and the basic infiltration rate I b , whereas, S w is a suggested term at steady infiltration rate. The calculated values of I b were corresponding to those obtained by infiltration experiment. This confirmed the significance of steady S w as a new functional infiltration parameter. A matching factor u was calculated as a ratio between predicted I b and the measured saturated hydraulic conductivity, Ks. The mean values of u were 0.895, 0.685 and 0.360 for calcareous, clay and saline clay soils respectively. Unsaturated K insert ignore into journalissuearticles values(θ ); has been discriminated into saturated macro-pore K insert ignore into journalissuearticles values(θ ); RDP and matrix unsaturated K insert ignore into journalissuearticles values(θ ); h . The values of Kinsert ignore into journalissuearticles values( θ ); RDP for macro pores remained higher than those for soil matrix pores insert ignore into journalissuearticles values(K insert ignore into journalissuearticles values(θ ); h ); in the studied soils. The highest value of K insert ignore into journalissuearticles values(θ ); was obvious in calcareous soil profiles, while the lowest value was existed in saline clay soil. In conclusion, the predicted values of hydraulic conductivities of soil matrix insert ignore into journalissuearticles values(capillary); and macro insert ignore into journalissuearticles values(non-capillary); pores were reasonable and existed in the normal ranges of the investigated soils, indicating that the proposed equations are applicable and can be recommended to be used in coarse and fine textured soils with large scale of different properties.
Keywords : Infiltration functions, soil pores, steady sorptivity, unsaturated hydraulic conductivity

ORIGINAL ARTICLE URL