ABSTRACT
A conventional geotechnical site investigation usually provides only a snap-shot of soil moisture conditions at a site, particularly when the profile is unsaturated. Although it is generally recognized that soil suction and moisture will vary from season to season and from year to year, designs are almost invariably based on what is discovered during a single short-term investigation. As a result, long-term problems may, and often do, arise that were not foreseen as a result of the site investigation. An evaluation of the annual water balance for a soil system provides a means of examining long-term conditions and predicting moisture changes in the soil. The paper illustrates the use of the water balance technique by means of three sets of data, two examples for natural soil systems and one for a municipal landfill. Complete data are not available for the three sites, and the examples given are of partial water balances.
