Development process of snowdrifts and capture rate of snow on cut-sections of roads

Abstract

Snowdrift observations were performed at the Ishikari Blowing-Snow Test Field in western Hokkaido on cut-sections of roads with slope heights of approximately 2 m and 1.5 m, which are considered to be places where it is relatively easy for snowdrifts to develop on road lanes. We evaluated the development process of snowdrifts and the rate of snowdrift captured on cut-sections of roads (capture rate: CR_Q) compared to total snow available for transport (snow transport rate). The maximum hourly snowdrift volume on cut-sections of roads (D_max) can be estimated by the relationship between D_max and the snow transport rate up to a height of 7 m (Q₇), or the wind speed at a height of 10 m (U₁₀). We clarified that the hourly snowdrift volume on the roadway of cut-sections of roads (D_la) varies, depending on the slope of the snow surface on the windward slope (i_sl), and tends to be minimum when i_sl is around 24°. CR_Q varied from 0.002 to 0.70 when Q₇ was 100 kg m⁻¹ h⁻¹ or more. CR_Q tended to decrease as Q₇ and the angles of wind direction for road direction (Ud′) increased, and to increase as air temperature (T), snowfall intensity (P), and the indexes (H_max, H_ave, W₁, i_max) for size and shape of the immediately preceding concave snow dune on cut-section of roads increased. Based on the results, we propose model equations for estimating CR_Q.