Sabo Dam Research Articles

Analysis on effect of compressed deformation at joints on destruction form of steel open sabo dam

Analysis on effect of compressed deformation at joints on destruction form of steel open sabo dam

Simulation of debris flows in the watershed of the Putih River, Indonesia using SIMLAR 2.1

In 2010, the eruption of Mount Merapi produced a huge volcanic material for debris flows. One area affected by the debris flows is the watershed of Putih River. To predict the impact caused by debris flows can be done by using software such as the Simulation Lahar (SIMLAR) 2.1. In this paper, debris flow modelling will be carried out using SIMLAR 2.1 in conditions without sabo dams and using sabo dams. This simulation aims to determine the effectiveness of the sabo dams in reducing the impact of debris flows. The data used are rainfall data, DEM and sediment data in Putih River. The results show that the sabo dam building can slow down the velocity of debris flow. In addition, sabo dams also function as a barrier to riverbed erosion in the Putih River watershed. Based on the results above, it can be concluded that SIMLAR 2.1 can predict the impact of debris flows in the Putih River watershed.

Study of Liquefaction Potential at Sabo dam Construction on Poi and Bangga River, Sigi Regency, Central Sulawesi

The Palukoro fault, an active sinistral fault that cuts through Sulawesi Island, was the cause of the earthquake and liquefaction disaster in Palu and Sigi Regency in 2018. A series of studies related to liquefaction have been carried out since then but more focused on the west side of the Palu River. This research will raise the potential for liquefaction on the eastern side of the Palu river, precisely in the sabo dam area at Poi and Bangga River. These rivers are located on the opposite side of the Sibalaya liquefaction area. Liquefaction potential was calculated using the Simplified Procedure Method based on NSPT values. Fifteen and twelve boreholes are located at Bangga and Poi rivers, respectively. The qualitative analysis assessed the criteria of vulnerability based on geological factors, groundwater levels, and seismicity. The Liquefaction Potential Index method was used and calculated using several earthquake scenarios based on historical data and potential earthquakes of The Palu-koro fault. Based on LPI analysis, the Poi River has meager potential at the middle stream area and moderate level potential at the downstream. Bangga River has moderate to high liquefaction potential downstream and low to very low potential at the middle stream.

Identification of Flood-prone Areas using HEC-HMS and HEC-RAS, the Case of Ciberang River Basin, Lebak District of Banten Province

It is common practice that flood hydrograph simulations help to provide better flood prediction and flood damage reduction planning. These efforts require information on flood-prone areas identification from the hydrological and hydraulic analysis results. Historically, the Ciberang River Basin has experienced floods. Those floods cause the loss of human life and damage some houses along the river’s channels, especially in Lebak District, Banten Province, Indonesia. The main objective of this study is to identify flood-prone areas based on the simulation result of a hydrologic and hydraulic model of catchment response due to several extreme rainfall events using HEC-HMS and HEC-RAS software. Rainfall and discharge data measured at the Ciberang-Sabagi water level gauge on 10 January 2013 were used to calibrate hydrological watershed parameters. The hydraulics channel routing is started from the planned location of the Sabo dam to the downstream control point. The next stage was the simulation of rainfall-runoff transformation and 1D unsteady flow channel routing for the 2, 5, and 10-years floods return periods. The main result of this study is a flood hazards map that shows the spatial distribution of the area and inundation depth for each return period of the flood.

PERENCANAAN SABO UNTUK MENGENDALIKAN LAJU SEDIMENTASI DI RAWAPENING

Rawapening has an area of 2,667 acres, which now ceases to exist. This natural reservoir serves to preserve water, control flood, generate electric turbine, and raw water resource. The depth of this lake decreases 42 cm annually, with the shallowing could cause flooding of the lakeside and and reducing the water supply. This study finds the additional amount of structure and dimension of sabo dam to prevent hazards at each river: at Panjang 2 (B=20m H=2m, and B=25m H=2,5 m), at Galeh 2 (each of B=8m H=2,4m), at Legi 2 (B=10m H=2m, and B=25m and H=2,5m), at Parat 1 (B=13m H=2,7m), at upstream Sraten 1 (B=15m H=2,7m), at downstream Sraten 1 (B=15m H=2,7m), and at Kedungringgis 1 (B=12m H=1,8m). Existing materials are fine and rough sand. Using WaTEM/SEDEM, saboplan guideline by processing the designed capacity, it is estimated that each river’s potential annual yield (in tonnes): Panjang 86.221,8, Galeh/Torong 45.138,24, Legi 42.404,04, Parat 28.579,32, Sraten 25.988,76, and Kedung Ringis 6.955,2. Overall, sabo dam is designed to be a closed type dam located in inlet rivers of Rawapening. Sabo dam construction holds 25% of potential sediment. Collectively, it adds a control volume of 2.885 m3, from 11.539 m3 to become approximately to become 14.424 m3. To cope with sedimentation in Rawapening, the structural approachment (sabodam) should be combined with non structural approachment such as restoring land use in the upstream area for more optimal sedimentation control.Keywords: Sedimentation, rawapening, erosion, WaTEM/SEDEM

ANALISIS GROUND VIBRATION DENGAN METODE PEAK PARTICLE VELOCITY (PPV)

<p><em>Measurement of Peak Particle Velocity (PPV) mm / sec in the Sabo dam construction project was carried out using seismic accelerometers. This study is to determine the value of PPV produced by construction equipment and then compared with the BS 6472-2: 2008 standard. The measurement method is carried out based on the applicable rules. PPV measurement results produced by each machine are different. In heavy equipment dump trucks, excavators, and front end loaders show PPV values at distances of 50 m, 100 m, 150 m and 200 m under safe conditions referring to the standard which is still in the range of 0.2 - 0.4 mm / sec. while for the pile driving device, demolition, vibrator pile driver at a distance of 50 meters are in unsafe conditions, because more than the range of 0.2 - 0.4 mm / sec, but at a distance of 100, 150, and 200 m PPV values are at safe condition</em></p><p><em><br /></em></p><p>Key words<strong>: </strong><em>PPV, Ground Vibration, Dam sabo</em></p><p><strong> </strong></p><p><em><br /></em></p>

Designing conduit sabo dam series as a debris flow protection structure

A high potential area for landslides was identified upstream of the Air Beras River on Bukit Beriti Besar which was feared to generate debris flow through the Air Beras River. One of the preventive efforts that can be conducted for debris flow is the sabo dam. This study aims to design a series of conduit sabo dams and evaluate the structure stability according to SNI 2851:2015 and Technical Standards and Guidelines for Planning and Design of Sabo Structures (JICA, 2010). By using the design discharge of debris flow of 120 m3/s, the velocity of 5.06 m/s, and the inclination of the riverbed of around 6.16°, the spillway height of the Sabo Dam 1 was determined to be 3 m, while the spillway height of Sabo Dam 1 was 2 m. The Sabo Dam 1 has a height of 10 m and a width of 30 m with a total manageable volume of 49,600 m3 while the Sabo Dam 2 has a height of 10 m and a width of 45 m with a total manageable volume of 91,500 m3. The safety factors of the sabo dam in the debris flow condition were 2.14 for overturning, 1.50 for sliding, and 5.74 for bearing capacity. Based on the result, the conduit sabo dam series effectively controls the destructive power of debris flow.

Survey on strength of construction joint of gravity type concrete Sabo dams

Survey on strength of construction joint of gravity type concrete Sabo dams

Experimental study on debris flow impact load against overturning limit of steel open type Sabo dam

Experimental study on debris flow impact load against overturning limit of steel open type Sabo dam

PEMODELAN POTENSI EROSI DAN SEDIMENTASI HULU DANAU LIMBOTO DENGAN WATEM/SEDEM

Erosion and sedimentation caused 4,000-hectare siltation in Limboto. Experts predicted that Limboto will be extinct in 2031. Revitalization program ‘Limboto Lake Revitalization’ has been carried out since 2017, with sabo technology as the action carried out to restrain sedimentation rate and to save the lake from extinction. This study aims to measure erosion and sedimentation potential in upstream of Limboto including 12 rivers (sub-DAS), using WaTEM/SEDEM model Two outputs resulted through this study are total sedimentation potential and identification of sedimentation zoning on each river. Based on soil type and other triggering factors, 5 of 20 rivers have the biggest sedimentation potential to deliver to Limboto, namely Batulayar 193.662 m3, Biyonga Baluta 123.095 m3, Alo1 120.273 m3, Alo 115.204 m3 and Molamahu 73.058 m3. The model was visually calibrated by considering the rivers’ sedimentation volume collected by JICA and BWS Sulawesi II. The result shows different score depending on the soil type, slope, land cover and other parameters. Sabo dam has to be reviewed regularly and on-schedule, since its current data is not actual and upstream rivers have highly dynamic and fluctuative sediment as well.

Failure analysis of steel open dam against an extreme boulder debris flow

This paper presents a failure analysis for a steel open-type Sabo dam (hereafter, steel open dam) against an extreme boulder debris flow load (hereafter, level II load) by a two-step analysis. The first step analysis is to estimate the level II load against the rigid wall by using the revised distinct element method (DEM). In the second step, the failure mechanism of a steel open dam is examined by using a dynamic elastic plastic analysis, in which the level II load-time relations obtained by the first analysis are multiplied by a reduction factor and then used. For the second step, the effects of the flange joint and dent deformation of the connection between column and beam are considered. Finally, a simple entire uniform load onto the steel open dam is proposed as a level II load model for the safety assessment.

Outline of measures for sediment disaster by the Sabo department of MLIT, Japan

From year to year, sediment disasters are getting more and more frequent and serious in Japan, resulting in the loss of many lives and properties such as houses and public work facilities. The Ministry of Land, Infrastructure, Transport and Tourism (MLIT) and other government agencies have long been taking various measures for disaster prevention and disaster reduction against sediment disasters. The Sabo Planning Division of MLIT supports the International Consortium on Landslides and the edition of the international journal “Landslides” as an advisory member. The Division also signed the Kyoto Landslide Commitment 2020 as the first signatories on 18 September 2019. In Japan, sediment disasters are defined as those caused by “debris flows”, “steep slope failures”, and “landslides”, and both tangible and intangible measures have been implemented constructing structures such as Sabo dams etc., and issuing evacuation precautions, etc. This paper reviews the activities of the Sabo works by MLIT to reduce sediment disasters as a signatory organization of Kyoto Landslide Commitment 2020.

Debris flow characteristics and sabo dam function in urban steep slopes

Debris flow characteristics and sabo dam function in urban steep slopes

Estimation of Debris Flow Sedimentation Volume Through Numerical Modelling

Implementation of potential debris flow hazard in Malaysia has been conducted by JabatanKerja Raya (JKR) in 2011. However, evaluation of this hazard level cannot deny the consequent to the nearest facilities. Thus, run-out analysis based on numerical modelling is easiest and competent way to evaluate the risk level. This paper presents a study on debris flow sedimentation volume with and without sabo dam by numerical simulation using Kanako 2D software. Kanako 2D software is widely being used in Japan and it is equipped with graphical user interface (GUI). A crossed verification upon numerical modelling and actual field data collection, and mitigation situation model that include sabo dam has been conducted. Results showing that Kanako 2D software have a precise output where the sedimentation volume is slightly higher around 5-15 %. It also proven that sabo dam can reduce the impact of debris flow because it can bear the sedimentation volume about 91%. In speeding up the process of setting landform in Kanako 2D, it recommended to use GIS to generate appropriates data. Thus, a laser scanning of topographical data is required.

Penerapan Teknologi Sabo sebagai Penahan Laju Sedimentasi Pada Muara Danau Limboto

Lake siltation due to erosion and sedimentation in Limboto Lake has happened since 1932. Based on 2017 analysis, lake contriction reached 4,000 (88,81 hectares annually). So, Limboto is predicted to go extinct in 2031. Since 2017, sabo dam implementation includes a series of effort called ‘Limboto Lake Revitalization’ to retain sedimentation flow. This study aims to review and to compare existing data with latest primary data collected. Measurement of sedimentation potential volume is done using software WaTEM/SEDEM, sabo design, and sabo plan. Overall, sabo plan designed by Sulawesi II River Basin Office is sufficient to accommodate potential of erotion and sedimentation flow in Limboto, despite the hypothesis that sabo dam amount is lacking and structure is positioned unfit with sabo design standard. The review shows that based on accommodating capacity, it is not necessary to add structure in upstream river. On the other hand, based distance between structures, each river requires at least 1 additional structure. This study advises an additional of capacity surge to 1.111.537 cubic meters. Batulayar section has the biggest capacity of 193.662 cubic meters per year, while the smallest is located in Tabongo1 with a capacity of 11.031 cubic meters per year. Updating and scheduled sabo dam review are required.

Analysis on the damage causes of sabo dam with one open cross section at upstream of Fuxing bridge in Lacus Creek

Lacus Creek is one of the important tributaries of the Laonong River upstream of the Gaoping River, which is an important river in southern Taiwan. After Typhoon Morakot in 2009, severe sediment disasters occurred, which affected the security of local revitalization, and the government has since invested in numerous projects to reduce the impact of sediment and flood disasters. In 2017, the Kaohsiung City government built a sabo type dam upstream of Fuxing Bridge in Lacus Creek; however, it was severely damaged by a heavy rain less than a year later. To investigate the cause of the damage, site investigations, concrete sampling tests, hydrology analysis, and reviews of the planning and design methods, construction process, etc. have been conducted, in order to understand the cause of the problem, avoid repeating mistakes, and clarify the responsibility of the administrative agency. The investigation and research found that many recent cases of torrent management have considered the transverse structures as isolated wildlife corridors, reduce the height of the transverse structures, create gentle slopes of the downstream surfaces, add fish passages, cut (openings) export slits, etc.; however, after setting up these environmentally friendly facilities, their effect and impact have not been explored in depth. This research survey found that, although the frequency of heavy rain events is not high in recent years, the current iterative impact of continuous rainfall may exceed the original design requirements. If the overflow mode with a single export opening is added, the scouring energy will be concentrated, and this additive effect is likely to cause the foundation of the sabo dam to lose bare space, and finally, the dam will be damaged. Therefore, it is recommended that when designing these torrent transverse structures, try to avoid using the method of a single narrow opening: it is better to increase the number of export openings (like a slit dam), expand the size of a single export opening, or adopt a fully enclosed dam design.

Post-analysis simulation of the collapse of an open sabo dam of steel pipes subjected to boulder laden debris flow

The objective of the proposed method is to utilize a site investigation of a debris flow disaster and verify a real scale analysis to evaluate the impulsive load on an open sabo dam. The Nagiso debris flow disaster which occurred in Nagano in 2014, where damage caused by Typhoon Neogri was studied. The verification result of the site investigation demonstrated the weak components of the open Sabo dam experienced damage owing to the debris flow. A discrete element method is normally applied to a solid body to calculate an interaction function force with respect to the contact point between boulders and the dam. The numerical method initially concatenates elements that model the open Sabo dam. Moreover, the stiffness coefficient of flanges and coupling joints between pipes was expressed to utilize the sectional partition method to determine the structural characteristics. The method was improved to separate from the connecting elements beyond the boundary conditions. The debris flow model uses a water flow distribution model, and the debris flow flowed from 200 m upstream of the open sabo dam. Accordingly, the proposed method was examined to verify the primary cause of damage to the open sabo dam and used to reproduce the circumstances that evaluated the impulsive load occurrence mechanism in the case of a real disaster. In addition, the coupling joints between the hollow steel pipes utilized a ‘reproduction analysis’ for a real sabo dam and a ‘reinforced analysis’ for a reinforced sabo dam were applied to assess the weak point of the dam.

Experimental study of the woody debris trapping efficiency of a steel pipe, open sabo dam

In recent years, the damage caused to human settlements in Japan by large woody debris (LWD) has been increasing. For example, the 2013 Izu Oshima typhoon resulted in a large number of fatalities and missing persons, and the Kagoshima Typhoon Disaster and Northern Kyusyu torrential downpour caused vast infrastructure damage due to the associated LWD. Current countermeasures for preventing LWD are insufficient to maintain the safety of residential areas. One type of protective barrier, the open sabo dam, has been constructed in Japan during the past 30 years. The primary function of open sabo dams is to block the flow of boulders, thereby also reducing sediment flow by reducing the gap size. However, because Japanese open sabo dams are designed specifically for boulder-trapping, the ability of these dams to trap LWD remains uncertain. In particular, many problems have been reported with respect to sediment trapping by driftwood with roots in an open sabo dam setting. The objective of this study was to examine the trapping efficiency of open sabo dams for LWD and sediment. The experimental approach clarified the influence of driftwood, without and with roots, on sediment trapping for a straight-channel flume. The flexible roots of the driftwood were shown to have a significant effect on the sediment trapping efficiency of the dam.

Evaluation of infrastructures and riparian area toward the potency of debris flow effect in Putih river watershed, Indonesia

Putih River is one of the rivers which was affected by debris flow after the eruption of Mount Merapi in 2010. The impact of the damage included riparian areas and infrastructures took place along the river. This research aims to evaluate the condition of riparian area in Putih river watershed with the established rules of Indonesian government and conditions of infrastructures that constructed along the river. The research was carried out by field survey that supported by Survey123 for ArcGIS and data processing using ArcGIS software. Based on the results, it shows that Jumoyo village had the largest of riparian area with 2.1 Ha for riparian area by 5 m width and 10 Ha for riparian area by 50 m width. The result also showed that Jumoyo village had the highest approximate population number within the riparian areas with 656 people for riparian area with 5 m width and 1465 people for riparian area with 50 m width. From the field survey result, it shows that there are 35 buildings/infrastructures in Putih River, consisting of 2 dams, 11 bridges, 1 ground sill, 20 sabo dams, and 1 sand pocket.

Evaluation on sabo dam construction planning Matakabo River at East Seram island

The Matakabo River is one of the major rivers in Maluku Province that crosses the Eastern Seram Regency. The Matakabo River is currently used for the Matakabo Irrigation Area through Matakabo Weir, with an area of + 3,050 Ha. Considering the number of tributaries entering the Matakabo River system and the risk of changes in land conversion in upstream, the development of Sabo Dam is seen as crucial for securing the water supply to irrigation as well as functioning as flood control. The location of 6 Sabo Dam is in Wai Sop, Wai Mol, Wai Sol, Wai Bemis, Wai Jana, and Wai Ines areas were based on visuals in the field where these areas are vulnerable to erosion and sedimentation. The calculation of flood discharge uses two methods, namely Nakayasu and ITB. Based on the highest river flow and flood capacity in the Q2: 401.68 m3 / second field which is close to the results of the synthetic discharge calculation from the ITB Method. Evaluation of 6 Sabo Dam with 1 Groundsill in Matakabo based on the calculation of the Van Rijn and Meyer Peter Muller (MPM) method will be able to accommodate sediment beds and suspended load around 1,275,958.63 m3 / year or around 0.581 mm / year. With 6 unit additional Sabo Dam locations (vol: 9,563,750 m3) equipped with groundsill, the estimated useful life of the river will not be disturbed by the sediment for about 7.5 years.