The Water Balance of Both Treated and Control Valleys

Abstract

Continuous records of soil moisture tensions throughout the 10-ft. profile at stations representing the upper, middle and lower sectors of each valley have shown only brief annual periods of moderate stress in the first 6 ft.. with uninterrupted maintenance of wet-soil conditions below this depth although sampling has indicated withdrawal of water at all depths. Despite substantial changes in the water content of the total 10 ft. of soil, each I-ft. layer has held available water throughout the three years with 13 in. or more always available from the profile. The well-distributed rainfall exceeded the annual open water evaporation in each year of records: only one IO-day period without rain was recorded between April. 1957 and December, 1960. Under these circumstances a fairly constant relationship between transpiration and open water evaporation can be expected from a continuous canopy of evergreen forest.