Sabo Dam Research Articles

Design Standard of Control Structures Against Debris Flow in Japan

Countermeasures to prevent or mitigate sedimentrelated hazards, debris flow in this paper are classified as structural measures or nonstructural measures. The structural measures are Sabo dams, leading dikes, and channels for debris flow control. The nonstructural measures are the designation of areas prone to debris flow, proper land use in the areas, the reinforcement of houses, the creation of warning systems and the evacuation of the inhabitants in case of emergency. A technical standard on debris flow control structures of Japan was revised in 2007. Major revision is that check dams called Sabo dams constructed near houses are changed from closed type Sabo dams to open type Sabo dams because the occurrence frequency is low as once for longer than one hundred years, natural torrent environment should be conserved in ordinary days and sediment trap capacity should be kept until debris flow occurs. Points changed are explained such as the opening of open type dams is as equal as the maximum stone size.

The 2006 pyroclastic deposits of Merapi Volcano, Java, Indonesia: High-spatial resolution IKONOS images and complementary ground based observations

On 16 June 2006 an overpass of IKONOS coincided with the emplacement of an active block-and-ash flow fed by a lava dome collapse at Merapi Volcano (Java, Indonesia). It was the first moving pyroclastic flow recorded on a satellite image. The very high-spatial resolution of the image indicated the extent and impact of pyroclastic material that was deposited during and prior to the day of image acquisition. A number of features associated with the hazardous block-and-ash flows emplaced in narrow, deep gorges were mapped, interpreted and analysed. The high-spatial-resolution IKONOS imagery worked extremely well for identifying pyroclastic deposits. The block-and-ash flow and surge deposits recognized in the IKONOS images include: (1) several channel-confined flow lobes and tongues in the box-shaped gorge; (2) thin ash-cloud surge deposit and knocked-down trees in constricted areas on both slopes of the gorge; (3) fan-like overbank deposits on the Gendol–Tlogo interfluves from which flows were re-routed in the Tlogo minor valley; (4) massive overbank flow lobes on the right bank of the Gendol River, which destroyed the village of Kaliadem 0.5 km from the main channel. A small part of this flow was re-channelled into the Opak tributary valley. The high-resolution IKONOS images also helped us to identify geomorphic obstacles that enabled flows to ramp up and spill out from the sinuous channel, as flow avulsion. Flow avulsions are dangerous as the redirect flows to unexpected areas away from the main channel. Valley fills from previous deposits, channel bends, and anthropogenic barriers in the channel (locally known as Sabo dams) influence the down valley passage of the flows. Sabo dams, originally built to ameliorate the effect of high sediment load streams, caused block-and-ash flows to avulse of the containing channel, and devastate populated areas.

New method of construction : The phased construction of the steel grid sabo dam

New method of construction : The phased construction of the steel grid sabo dam

History and futures assignment of technology for open type steel SABO dams

History and futures assignment of technology for open type steel SABO dams

Study on seismic resistance evaluation for Sabo dam using earthquake observation records

Study on seismic resistance evaluation for Sabo dam using earthquake observation records

Evaluation of the effect on Bili-bili Dam in Indonesia as a sabo dam by numerical simulations

Evaluation of the effect on Bili-bili Dam in Indonesia as a sabo dam by numerical simulations

Debris flow simulation based on stabilized FEM in penetration type Sabo dam

Debris flow simulation based on stabilized FEM in penetration type Sabo dam

Numerical simulation method of debris flow introducing the non-entrainment erosion rate equation, at the transition point of the riverbed gradient or the channel width and in the area of sabo dam

Numerical simulation method of debris flow introducing the non-entrainment erosion rate equation, at the transition point of the riverbed gradient or the channel width and in the area of sabo dam

Case analysis of flood sediment discharge in a stream segment regulated by a series of sabo dams

Case analysis of flood sediment discharge in a stream segment regulated by a series of sabo dams

One-dimensional numerical simulation for sabo damplanning using Kanako (Ver. 1.40): A case study at Cipanas, Guntur Volcanoes, West Java, Indonesia

. Sumaryono. (2008): Debris flow simulation and sabo dam planning by Kanako, Report for the Japan International

Impulsive force of debris flow on a curved dam

Although Sabo dams are an efficient method for river and basin management, traditional Sabo dams have a great impact on ecology and landscape. Moreover, such dams are hit and often damaged by great impulsive force when they block the debris flow. Therefore, alternative shapes for Sabo dam deserve thorough investigation. In this investigation, a curved dam was designed by changing the upstream-dam-surface geometric shape to reduce the impulsive force of the debris flow, with enhanced stability and reduced concrete mass being the anticipated outcomes. In this study, the flume and laboratory facilities simulated the impulsive force of the debris flow to the Sabo dams. Three geometric forms, including vertical, slanted and curved Sabo dams, were used to determine the impulsive force. Impulsive force theories of the debris flow were derived from the momentum equation and the Bernoulli equation. In these, the impulsive force was balanced by the friction force of the Sabo dam and the opposite force of the load cell behind the dam as it was hit by the debris flow. Positive correlations were found when comparing the experimental data with the theoretical results. These findings suggest that our impulsive force theory has predictive validity with regard to the experimental data. The results from both theory and experimental data clearly show that curved dams were sustained less force than the other dams under the same debris flow. This comparison demonstrates the importance of curved geometry for a well-designed Sabo dam.

Development of “Kanako 2D (Ver.2.00),” a user-friendly one- and two-dimensional debris flow simulator equipped with a graphical user interface

Debris flows often cause substantial losses of human life as well as economic losses. Damage can be estimated using numerical simulation models that describe the debris flow process. Some models can be used to determine the possible effects of sabo dams and have been practically employed to plan sabo dam arrangement. However, the existing simulation systems currently do not have efficient user interfaces, making it difficult for non-experts in debris flow simulations to run simulations without the aid of specialists. We developed a system that produces one- and two-dimensional debris flow simulations and is equipped with a graphical user interface. The system is based on an integration model and employs one-dimensional simulations of gully areas and two-dimensional simulations of alluvial fan areas; it then considers mutual influences in boundary areas between gullies and alluvial fans. Data can be input using a mouse and viewed on the monitor, and users can see real-time visualized images of a debris flow during a simulation. The interface enables users to run a debris-flow simulation without expert knowledge of the model, enabling better solutions for sabo engineering.

砂防ダムを含む山地小流域の水文諸量と出水遅延効果について

砂防ダムを含む山地小流域の水文諸量と出水遅延効果について

Case study about sediment control by a series of slit sabo dams

Case study about sediment control by a series of slit sabo dams

The decrease in the dissolved oxygen concentration caused by sediment flushing from sabo dams and its prediction

The decrease in the dissolved oxygen concentration caused by sediment flushing from sabo dams and its prediction

Debris flow control with steel open-type Sabo dams constructed at base point

Debris flow control with steel open-type Sabo dams constructed at base point

Study on new type slit sabo dam development for reduction of slit blockade by drift woods

Study on new type slit sabo dam development for reduction of slit blockade by drift woods

Numerical simulation on a debris flow in a mountainous river with a Sabo dam

Numerical simulation on a debris flow in a mountainous river with a Sabo dam

Factors affecting vegetative invasion of the sediment trap area of sabo dams in the Mogami River basin using aerial photograph

Factors affecting vegetative invasion of the sediment trap area of sabo dams in the Mogami River basin using aerial photograph

EXPERIMENTAL STUDY ON DEBRIS FLOW CAPTURING PROCESS OF GRID TYPE SABO DAM

The debris flow capturing process of the grid type sabo dam was clarified experimentally. The process could be explaned as follows; the dam was blocked by debris flow and the sediments deposited upstream of dam. The blocking was affected by the three-dimensional interlocking of gravel near the open spaces. After the blocking of dam, the incoming debris flow jumped due to the collision with the deposited layer. Then, the jumped sediments were divided into the sediments which got over the dam and the ones which returned back and deposited. Then, incoming debris flow ruched over the dam accompanying with the erosion of deposited layer. The debris flow discharged from dam and deposited upstream of dam intermittently by such a process. The separation of sands and gravels occurred by the deference of repulsion force in the process of debris flow jumping and the gravels deposited above sands, that is, the reverse-grading phenomenon of deposition.