Role of Sabo Facilities

What are Sabo Works?

? Sabo works mainly involve the construction of sabo dams (check dams) in remote mountain areas. Because of the principal locations of such works, the general public does not often see them and the necessity for and role of sabo works are seldom understood. If devastated mountain land is left unattended, however, the sediment discharged from this land raises the riverbed in the lower reaches, thus increasing the likelihood of flooding and sediment disasters.
 Sabo works protect the lives of the public and national land from sediment disasters which devastate land with rich greenery, threaten precious lives and destroy houses, roads and railway lines by means of the construction of sabo dams and channel works.

Functions of Sabo Dams

 A sabo dam is constructed upstream of a devastated torrent at a site where sediment production and discharge is especially large. It stores the sediment which runs down from the upstream in order to reduce the discharge downstream and also prevents the outflow of unstable sediment deposited at the bed of a torrent.
 When a sabo dam stores sediment up to its capacity, the river width is widened with the resulting effects of creating a gentler torrent bed gradient and weakening the potential force of sediment flow or running water, preventing the collapse of the river banks. A sabo dam is also capable of preventing sediment disasters by means of temporarily storing sediment to reduce the volume of sediment outflow downstream.

Without sabo dams....
With sabo dams...

Functions of Channel Works and Groundsels

 A group of channel works and groundsels is introduced at a high flood hazard site with extremely turbulent flow in a fan or area of sedimentation to create a safe stream with a fixed course. They are also constructed for a torrent which threatens houses and farmland is surrounding areas through bank erosion because of the low relative height of the riverbed vis-a-vis houses/farmland. As these structures are generally constructed to create a new channel, which is lower than the surrounding land, they solve the problem of a river of which the bed is higher than the surrounding land. Even if a flood occurs, the water can easily find its way back to the river with minimum damage to houses and farmland, etc.

Without channel works and groundsels...
Sabo works required preventing extensive damage
Sabo dams reduce the level of sediment discharge from the upstream while channel works prevent the erosion of and sediment flow to surrounding areas.
Facilities, which are essential for the safety and development of local areas, are constructed under sabo works.
With channel works and groundsels...