Soil Moisture Depletion, Actual and Potential Evapotransipration in an Engelmann Spruce-Subalpine Fir Forest
The average soil moisture depletion (OSM) measured on four plots for the 1970 growing season was found to be 10.3 inches in an Engelmann spruce-subalpine fir forest. Since precipitation during the same period was 2.6 inches, actual evapotranspiration (ET) was estimated to be 12.9 inches by the relationship: ET = ASM + precipitation.Measurements of hydraulic head showed downward drainage followed by upward unsaturated flow during the 1970 growing season across the lower boundary at which soil moisture was measured. Net drainage (D) of 3.6 inches was estimated for the 1970 growing season. Since roots probably exist below the depth of measurement, some of this drainage water may ultimately go to transpirational loss. The plant factor, ratio of actual evapotranspiration to potential evapotranspiration, was found to be 0.608 by ignoring the unsaturated flow component of soil water.
Eaton, Frank D. (1971). Soil moisture depletion, actual and potential evapotransipration in an Engelmann spruce-subalpine fir forest. MS. 86p.