Mark Walker

Abstract:
Snow accumulated in mountainous areas is the source of water supply for much of the western United States. Estimates of the expected amounts of annual discharge in rivers are based on snow water equivalence (SWE) measurements and regression models that have climate stability as an underlying assumption. This is likely to be untrue as climate changes. This suggests that assessments of water availability change from statistical models to physically-based models. However, the current data collection network for SWE provides sparse areal coverage. Inexpensive wireless sensor networks and simple estimation techniques could be used to extend the areal coverage of snow data to improve spatial resolution. We report results of deployment of a prototype wireless sensor network, Snowcloud, at the Sagehen Creek, CA experimental field station. The network reported snow depth and temperature from January—May, 2010. A simple estimate of SWE at each node was based on the assumption of stability of the ratio SWE/SD and predicted SWE with reasonable accuracy (average difference of+ 1.0 cm (0.4 in), standard deviation= 3.0 cm (1.2 in)). Regression analysis indicated significant associations (P<. 05) between SWE and% canopy closure to the north, weekly total incoming solar radiation and monthly average temperature. These results indicate that wireless sensor networks measuring SD can be used to extend information from snow measurement sites accurately to give estimates of water availability in snowpack.