Quantifying snow water equivalent using terrestrial ground penetrating radar and unmanned aerial vehicle photogrammetry

This study demonstrates the potential value of a combined unmanned aerial vehicle (UAV) Photogrammetry and ground penetrating radar (GPR) approach to map snow water equivalent (SWE) over large scales. SWE estimation requires two different physical parameters (snow depth density), which are currently difficult measure with spatial temporal resolution desired for basin-wide studies. UAV photogrammetry can provide very high-resolution spatially continuous depths (SD) at basin scale, but does not densities. GPR allows nondestructive quantitative investigation if velocity is known. Using photogrammetric two-way travel times (TWT) reflections snow-ground interface, velocities in snowpack be determined. Snow density (RSN) then estimated from propagation (which related electrical permittivity snow) via empirical formulas. A Phantom-4 Pro MALA GX450 HDR model mounted on ski mobile were used determine parameters. snow-free digital surface (DSM) was obtained survey conducted September 2017. Then, another synchronization February 2019 whilst approximately its maximum thickness. Spatially calculated by subtracting DSM snow-covered DSM. Radar along lines computed using UAV-based obtain densities SWEs. The root mean square error SWEs (384 mm average) 63 mm, indicating good agreement independent observations lies within acceptable uncertainty limits.