MAXIMAL CAPILLARY RISE FLUX AS A FUNCTION OF HEIGHT FROM THE WATER TABLE

Isothermal capillary rise was allowed from a fixed water table in soil columns of different soils of Haryana, India, to continue til the maximum height of capillary rise was reached. Maximal capillary rise flux qm was monitored along the advancing wetting front at various heights in the soil columns. The qm data fit satisfactorily the analytical solution of a flow equation with hydraulic conductivity K(h) being related exponentially with suction h as K(h) = ae−b(h-h→), where ha is the air entry suction head. The saturated hydraulic conductivity K, and wilting point &thetas;wp were related empirically to the soil constants A and b. The empirical relationships established were ln (A/a) = 5.636 + 1.326 x 10−6 K→ – 0.31 &thetas;wp; and b = 0.1068 + 6.547 x 10−8 K→ – 4.563 x 10−3 &thetas;wp, where A = aebh→. This may be used for determining more simply and quickly the maximal capillary rise flux qm as a function of height from water table z, and the hydraulic conductivity K as a function of suction h from the readily determinable K→ and &thetas;wp. Air entry value h→ is also shown to be estimated from K→ and &thetas;wp.