Apparatus and method for monitoring snow water equivalent and soil moisture content using natural gamma radiation

摘要

A gamma monitoring apparatus and method for measuring water equivalent of snowpack over a selected ground area. A detector unit is installed at a given height above the area. The detector unit has a collimator and a scintillator coupled to a photomultiplier tube for detecting gamma rays emitted by naturally radioactive elements present in soil under the snowpack and absorbed by the snowpack in a field of view defined by the collimator. Pulses in a signal produced by the photomultiplier tube are measured and those exceeding threshold energy levels in a number of energy windows are registered as gamma counts. The water equivalent of the snowpack is periodically computed as functions of the gamma counts in the energy windows and the height of the detector unit with respect to ground level. The data representing the computed water equivalent are stored and controllably transmitted for reporting. Soil moisture content is also determinable.