What kinds of works does Fuji Sabo Office do?
Protecting Lives from Disasters
Works to countermeasure disasters
Measures at the Southwestern Valley
At the foot of Mt. Fuji are many mountain streams.
Usually dry, these streams become overflown with debris flows caused by rains in early winter
and late spring.
Fujinomiya and Fuji cities, both located at the southwestern foot of Mt. Fuji, have suffered
from many debris flow disasters from these mountain streams, which spread from the highest peak
of Japan all the way down to the coast.
Because of this, policies regarding disaster prevention measures for the southwestern foot was
examined in 1980, and further countermeasures have been implemented since 1983 at high-need
mountain stream areas.
So far, there have been projects at Inokubo river, Ashidori river, Kazamatsuri river, Yumisawa
river, the Senzoku branch of Akabuchi river, Sudo river, Bonpu river, and maintenance projects
for sedimentation basins and check dams have also been widely implemented.
Sediment basins
Because the valleys of Mt. Fuji is narrow and shallow, they are dug out to make space to
accumulate sediment, so that sediment flows can be stopped when they flow down.
These basins are constructed in Inokubo river, Osawa river, Ashidori river, Kazamatsuri river,
and Yumisawa river. Once sediments have accumulated, stone removal work will be conducted.
 【 Kazamatsuri river sediment basin】 |
Check dams (sabo dams)
Sabo dam work is effective against erosion of riverbeds and valleys caused by debris flows, can temporarily store sediment so that it does not overflow, and can control sediment flows in the events of small or medium-scaled floods.
 【Bonpu No.1 Check dam】 |
 【Sudo No.3 Check dam】 |
Conservation of Mountain Stream
In previous channel consolidation work, the channels were often straight and fixed to prevent flooding and longitudinal erosion of the river. The mountain stream conservation works currently under construction are construction methods that harmonize natural landscape and surrounding environment, such as taking into account original river channels, reinforcing riverbanks only where necessary, and ensuring safety at slopes by the forests.
 【Tamenosawa Mountain Stream Conservation Work】 |
 【Okubosawa Mountain Stream Conversation Work】 |
The next page explains the measures taken at the Osawa Alluvial Fan Area.
