Determination of Evapotranspiration Using the Neutron Scattering Method

Abstract

The accuracy of evapotranspiration (E.T.) determinations by the neutron scattering method was^found by studying each of the possible errors. For the gravelly"soils srudied the probable eriorln E,.T. was leis than 0.15 in. of water for a #eekly period and less than 0.62 in. for a 3-month period when one sampling site was used. Increasing the numbcr of sampling sites decreased the error bu"t not in direct proportion.' The metl-rod rvas used to provide values for evapotranspiration from irrigated and unirrigated corn, wheat, and clover.

Effects of long-term water table drawdown on evapotranspiration and vegetation in an arid region phreatophyte community

“…Soil moisture was measured in the pre-drawdown period using the neutron scattering method (Bowman and King, 1965) at 15-cm intervals down the soil profile and calibrated using soil samples collected near access tubes (Stannard, 1993). During the postdrawdown period, soil moisture was measured by time domain reflectometery using Campbell scientific 615 probes, with one probe installed at 0-30 cm and 30-60 cm soil depths.…”

EVAPOTRANSPIRATION AND SOIL MOISTURE DYNAMICS ON A SEMIARID PONDEROSA PINE HILLSLOPE1

“…The water balance approach has been used in a number of studies to determine forest hydrologic budgets and ET (Bowman and King, 1965;Calder, 1976;Black, 1979;Spittlehouse and Black, 1981;Giles et al, 1985). Although the technique yields an indirect measure of ET that is necessarily dependent on the accuracy of measurements of all other components, direct measurement techniques (i.e., turbulent transfer methods) of ET over heterogeneous surfaces such as semi-arid forest are difficult and require extensive instrumentation.…”

The Water Balance of an Agricultural Catchment. I. Estimation of Evaporation From Soil Water Records

“…For example, the standard deviation of the maximum deficit at the time of harvest, is about 2 10-15 mm. Similar variability of soil water deficits developed over periods of several weeks are quoted or can be calculated from the results of Stern (1965), Bowman and King (1966), Colville (1964, 1970), Kitching (1 967), Van Bavel and Stirk (1 967), Sartz (1 972).…”