Many communities, particularly those at high elevations, are dependent on seasonal snowmelt for water, hydropower generation and irrigation ( Smith T. In many Himalayan river catchments, the contribution of seasonal snowmelt to mean annual runoff equals or exceeds that of glacial melt ( Prasch et al., 2013 Rohrer et al., 2013 Lutz et al., 2014). High Mountain Asia’s cryosphere delivers water resources to over one billion people ( Barnett et al., 2005 Bookhagen and Burbank, 2010 Immerzeel et al., 2010 Bolch et al., 2012 Gardner et al., 2013 Smith T. We recommend that a similar instrument setup be extended into remote Himalayan environments to facilitate widespread snowpack monitoring and further our understanding of the high-altitude water cycle. Our monitoring approach provides high quality, continuous, near-real time information that is essential to develop snow models in this data scarce region. The application of sub-daily time-lapse camera imagery can help to correctly interpret and increase the reliability and representativeness of snowfall measurements. Precipitation gauges significantly underrepresent the solid fraction of precipitation received at this elevation by almost 40% compared to the gamma ray sensor. Over their typical ∼6-month lifetime, snowpacks in this setting can attain up to 200 mm SWE, of which 10–15% consists of mixed precipitation and rain-on-snow events. The instrument setup performs well for snowpacks >50 mm SWE, but caution must be applied when interpreting measurements from discontinuous, patchy snow cover or those that contain lenses of refrozen meltwater. We assess the accuracy, spatial representativeness and the applicability of the SWE and snow depth measurements using time-lapse camera imagery and field observations. in the Nepal Himalayas to quantify the evolution of SWE and snow depth over a 2-year period. Here, we use a passive gamma ray sensor that measures snow water equivalent (SWE) and complementary meteorological instruments installed at 4962 m a.s.l. Seasonal snow is an important component of the Himalayan hydrological system, but a lack of observations at high altitude hampers understanding and forecasting of water availability in this region. 5Department of Physical Geography, Utrecht University, Utrecht, Netherlands.4Norwegian Water Resources and Energy Directorate, Oslo, Norway. 3British Antarctic Survey, Natural Environment Research Council, Cambridge, United Kingdom.2Scott Polar Research Institute, University of Cambridge, Cambridge, United Kingdom.1International Centre for Integrated Mountain Development, Kathmandu, Nepal.Stigter 5, Knut Møen 4, Amrit Thapa 1, Kjetil Melvold 4 and Walter W.
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