Received: 29 Aug 2017 – Discussion started: 25 Sep 2017
Abstract. Downward flux of percolating meltwater was measured quantitatively in an in situ vertical profile, in an alpine snowpack, at a remote location. Three separate measurement systems were used to obtain multiple parameters required to calculate percolation flux. Brooks-Corey constitutive parameters were measured in a 0 °C isothermal snow sample test cell, and then applied to an on-site snow column test. The instrumented column test allowed calculation of fluxes, that were then calibrated to measured outflow to empirically determine an appropriate value of zeta potential. In situ measurements with data logging of self-potential (SP) and capillary pressure sensors then allowed calculation of flux from SP measurements (qsp), expressed as darcy velocity, over a multi-day period. The results strongly reflected diurnal snow melt dynamics, and daily peak qsp ranged from 5.6 to 105 cm/d. qsp was comparable to actual fluxes, represented by changes in snow water equivalent (SWE) (2.5 to 5.3 cm/d) measured at an adjacent USDA SNOTEL station. The average error in qsp was 8 % over a four-day period, with total calculated flux of 18.1 cm, compared to a 16.8 cm change in SNOTEL SWE. Daily (24-hour period) errors ranged from +26 % to −47 %. The methodology developed herein can combine SP with either capillary pressure or saturation measurements. The ability to measure meltwater percolation flux in snowpacks may support mathematical modeling of unsaturated flow processes in melting snow, and may supplement studies of snowmelt-groundwater and snowmelt-runoff interactions and glacier mass balance studies.
How to cite. Clayton, W. S.: In situ measurement of meltwater percolation flux in seasonal alpine
snowpack using self potential and capillary pressure sensors, The Cryosphere Discuss. [preprint], https://doi.org/10.5194/tc-2017-187, in review, 2017.
Downward percolation of water in melting snowpacks is a factor effecting the survival of glaciers as well as the water balance in areas dependent on snowmelt for water supply. Meltwater percolation flux in a snowpack was measured for the first time using an emerging method known as electrical self-potential, developed by others. Measured meltwater percolation flux was compared to snowpack measurements at an adjacent advanced weather station, and the average error was 8 % over a four-day period.
Downward percolation of water in melting snowpacks is a factor effecting the survival of...