Date of Award:


Document Type:


Degree Name:

Master of Science (MS)


Plants, Soils, and Climate

Committee Chair(s)

Sterling A. Taylor


Sterling A. Taylor


Norman Bauer


Rex L. Hurst


Cleve H. Milligan


The movement of water in soil presents many interesting problems to the research worker. It is also a subject which finds wide and important application in agriculture and several branches of engineering.

The object of this work was to examine the usefulness of a new equation of flow of water in unsaturated soil. If valid, this new approach may be able to eliminate some of the gaps in our present knowledge of the subject.

All soil lying above the capillary fringe of a water table is in the unsaturated state with respect to water. This means that in any macroscopic volume element of soil three phases are present-- solid, liquid and gas. The volume fraction of each of these phases show wide variation in both space and time in field soils. The variation in both space and time in field soils. The variation in the volume fraction of the liquid or water phase is accompanied by a considerable change in the physical properties of the water. In the strictest sense the unsaturated state covers all intermediate conditions between saturation and an incomplete monomolecular layer of absorbed water.

It is important to recognize that the solid phase is also dynamic. It consists of unconsolidated particles with great variation of size and shape. Many solid phase properties show a complex dependence upon the amount of water present. Swelling and shrinking are well known in soils and these changes affect water movement.



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