Snow Accumulation and Melt Estimation Incorporating Temporal Variations in Snow Density

ABSTRACT In cold regions across the globe, snowpack dynamics play a fundamental role in regulating hydrological regimes, influencing water resource availability, and triggering natural hazards such as floods, landslides, and debris flows. As climate warming accelerates, particularly in high‐latitude and high‐altitude areas, the need for accurate snow accumulation and snowmelt estimation has become increasingly critical for both environmental management and disaster risk reduction. To overcome the limitations of traditional constant‐density assumptions, this study presents an improved snow accumulation and snowmelt estimation approach incorporating temporal snow density variability and compaction effects. Subsequently, a comparative assessment of six widely used snow density estimation models is conducted based on the observed snow depth and density measurements. Results demonstrate that snow density estimation requires partitioning the entire snow cover duration into two distinct phases, that is, snowpack season and snowmelt season, and accurate snow density estimation must separately account for compaction effects induced by snow depth and duration of snow cover during the snowpack season and snowmelt season. That is, during the snowpack season, the increases in snow density are mainly caused by the gravitational compaction of overlying fresh snow layers, while during the snowmelt season, the snow density enhancement is predominantly governed by the duration of snow cover. Afterward, based on the proposed snow accumulation and snowmelt estimation approach, the impacts of temperature rise induced by climate change on snowpack dynamics were systematically investigated. Results indicate that the rising temperatures contribute to a reduction in snow depth during the snowpack season, primarily in the initial unstable phase of snowpack formation. Conversely, during the snowmelt season, temperature increases exert a more pronounced influence on snowmelt dynamics. Analysis of meteorological data from Nakayama Pass, Hokkaido, Japan, indicates that for every 1.0°C increase in temperature, the duration of snow cover at this location will be reduced by approximately 14.5 days, which may have implications for understanding snowpack responses to climate warming in other snow‐dominated regions. The findings of this study provide critical assessment benchmarks and modeling support for evaluating snowmelt‐induced disasters, including but not limited to floods, landslides, and debris flows.