Journal of the Japanese Society of Snow and Ice

Relationship between Foreknowledge of Occurrence of Snow Jam and Meteorological Elements

Hiroshi KAMAYACHI

1969Volume 31Issue 2 Pages 30-36
Published: March 30, 1969
Released on J-STAGE: July 23, 2009

DOIhttps://doi.org/10.5331/seppyo.31.30

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To eliminate the snow jam automatically at Kamimatsuzawa power station, the relation between the occurrence of the snow jam and meteorological elements was analyzed.
The main results obtained from this analysis are sammarized as follows :
1. Linear correlation was obtained between the occurrence days of snow jam in a year and the product of the average of minimum air temperature of days in January and February by the total precipitation in that period. The secular variation of the occurrence days of snow jam in a year has the period of eleven years and there is negative correlation between the variation and solar spot.
2. To measure the water temperature is very useful for the foreknowledge of the occurrence of snow jam. For instance, it is possible to foreknow the occurrence of snow jam by means of measurement of the water temperature at 9 O'clock. However, it is impossible to foreknow the occurrence of snow jam certainly by measurement of air temperature or precipitation.

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On the Function of the Slat Snow Fence

Takeo HATANO, Tokuo IMAI

1969Volume 31Issue 2 Pages 37-43
Published: March 30, 1969
Released on J-STAGE: July 23, 2009

DOIhttps://doi.org/10.5331/seppyo.31.37

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The purpose of the research is to settle the following problems.
1) How high should the snow fences be ?
2) How density ratio should be ?
3) How far should they be placed from the track ?
As a method of measurements, we installed the slat snow fences various density ratio in field, and then examined snow drift depth and wind velocity distribution around the fence.
Investigating the data of measurements, we obtained the following results.
1) The following relation between the length from the fence to top of snow dune and density ratio were obtained.
When there is no gap below the fence.
l_m=4.63PH_F
When there is a gap of 60 cm below the fence.
l_m= (1.84+4.63P) H_F
l_m……the length from the fence to top of snow dune.
P……density ratio
H_F……height of the fence
2) At saturation point of the fence with snow drift, the length of the leeward snow dune were obtained each density ratio.
3) As a big pocket appear between the slat fence and snow dune, the effects of fence are kept long.

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Artificial Release of Avalanches

Fumiaki KOBAYASHI

1969Volume 31Issue 2 Pages 44-49
Published: March 30, 1969
Released on J-STAGE: July 23, 2009

DOIhttps://doi.org/10.5331/seppyo.31.44

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Artificial release of avalanches with explosives for the protection of roads were conducted during the four winters of 1965-1968.
The amount of explosives, distance of detonation centres and time intervals of blasting, designed to produce an adequate release of the snow, structure and moisture of snow and slope inclination.
The explosives were encased in a vinyle chloride pipe in an attempt to produce uniform propagation of the blasting pressure to the surrounding mass of snow and to increase the cracking zone.
It was shown that artificially indused snow avalanches can be produced at will by blasting at intervals of 0.25-0.75 second from the lower side to the upper parts in the detonation area.
Three types of blasting were conducted : total snow removing work, snow roll-in work and cave crushing work. The results were good in all three cases.

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