THEORY OF WATER MOVEMENT IN SOILS: 6. EFFECT OF WATER DEPTH OVER SOIL

IN A PREVIOUS PAPER IN THIS SERIES THE AUTHOR DEVELOPED A GENERAL TECHNIQUE FOR STUDYING THE MOVEMENT OF WATER IN POROUS MEDIA. THE PRESENT PAPER EMPLOYS THIS TECHNIQUE TO ANALYZE THE EFFECT OF A NONZERO WATER DEPTH. THE CASES ANALYZED ARE ONE-DIMENSIONAL ABSORPTION AND INFILTRATION. IN THE FIRST CASE THE RESULTS ARE INDISTINGUISHABLE FROM THOSE OF PHILIP, BUT THE NEW METHOD HAS THE ADVANTAGE OF YIELDING RESULTS IN ANALYTIC FORM IN THE ABSENCE OF GRAVITY. AGREEMENT IS ALSO GOOD IN THE SECOND CASE EXCEPT FOR LONGER TIMES, WHEN THE NEW TECHNIQUE OFFERS THE ONLY SOLUTION. IT IS SHOWN THAT THE INFILTRATION SOLUTION IS SIMPLIFIED WHEN TIME APPROACHES INFINITY; TERMS ARE INTRODUCED THAT VARY LOGARITHMICALLY WITH TIME. THE EFFECT OF WATER PRESSURE IS STRONGER FOR A SOIL THAT HAS A HIGHER INITIAL WATER CONTENT.