Aerial measurement of snow water equivalent by terrestrial gamma radiation survey

Abstract

Research studies measuring terrestrial gamma radiation from aircraft to determine snowpack water equivalent are reported. Both spectral and total count data were collected using 10-16 em by 10-16 em (4 in.) NaI (T1) scintillation crystals. Extensive ground truth data were used in conjunction with count rates obtained to develop empirical procedures relating count attenuation with snow water equivalent. Soil moisture, altitude, and air density corrections were made in the course of development of the method. Spectral relations are compared with theoretical. Significant limitations on data collection and interpretation imposed by the presence of radon gas are discussed. Because of radon gas interference in the total count, the spectral method gives the best measurement of water equivalent in the snow-flood sensitive North-Central United States. © 1973 Taylor & Francis Group, LLC.