scholarly journals Rainfall Monitoring to Support Temporal and Spatial Information of Debris Flow Initiation in Merapi Volcano

2021 ◽  
Vol 13 (3) ◽  
Author(s):  
Ani Hairani ◽  
◽  
Adam Pamudji Rahardjo ◽  
Djoko Legono ◽  
Istiarto Istiarto ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Debris Flow ◽  
Rainfall Intensity ◽  
Spatial Information ◽  
Line Graph ◽  
Warning System ◽  
Surface Flow ◽  
Merapi Volcano ◽  
Hourly Rainfall ◽  
Debris Flow Initiation

Debris flow frequently attacks rivers on slopes of Merapi Volcano and causes fatalities and damage of infrastructures. To reduce the risk of debris flow, a warning system has been developed by Sabo Office Center. Critical line and snake line graph are applied in Merapi Volcano to monitor characteristics of rainfall in the upland river basin. However, this warning system cannot predict the arrival time and location of the debris flow occurrence. Numerical simulation seems to be a good tool to improve its performance. This research proposed an idea to combine rainfall-based warning system with the numerical simulation model. This model used slope stability theory to identify debris flow initiation. Results of this research showed that fluctuation of rainfall intensity reflects changes of debris flow initiation area. The more severe rainfall intensity, the larger volume of surface flow, and thus the greater debris flow initiation takes place. When the rainfall monitoring is combined with the debris flow simulation results, there is a tendency of the enlargement of the debris flow area to follow the growth of the hourly rainfall.

scholarly journals Analisis Karakteristik Hujan Ekstrim Untuk Mendukung Pengembangan Peringatan Dini Lahar Dingin di Lereng Gunung Merapi

2020 ◽  
pp. 35-40
Author(s):  
S.Y. Iryani
Keyword(s):  
Relative Frequency ◽  
Rainfall Intensity ◽  
Critical Line ◽  
Negative Impact ◽  
Warning System ◽  
Extreme Rainfall ◽  
Public Infrastructure ◽  
Rainfall Characteristics ◽  
Rainfall Analysis ◽  
Hourly Rainfall

Mt. Merapi cold lava disasters in 2010 had caused a lot of public infrastructure and facilities in the area around Mt. Merapi were damaged, due to the occurrence of debris flows triggered by extreme rainfall. Analysis of extreme rainfall characteristics are conducted to determine the pattern of distribution of the amount of hourly rainfall  in the slopes of Mt. Merapi. To reduce the negative impact caused by cold lava flood, it is necessary to plan an Early Warning System (EWS) and the proper evacuation measures. EWS based Rainfall intensity, can refer to the Critical Line Curve. The research  results showed the greatest rainfall intensity occurred in the Mt. Maron station Pwith the cumulative relative frequency of rainfall intensity >20 mm/hr in between the years 1988 to 2010 with 6.74%. Analysis of the incidence of the most extreme hourly rainfall of 14 rainfall stations in the slopes of Mt. Merapi in 1988 to 2010 occurred in kemasan station in 2010 with 621.5 mm in January at 6:00 p.m. to 7:00 p.m. Critical Line Curve Kali Gendol rain station Batur, Deles and Sorosan, non-causing rainfall in the dangerous area is 24 events (13.79%), causing rainfall in the dangerous area is 4 events (2.30%) and non-causing rainfall in the safety area is 146 events (83.91%). Cumulative Relative frequency rainfall intensity >20 mm/hr at rainfall stations close to the Kali Gendol i.e. Batur, Deles and Sorosan rainfall station from the highest to the lowest are   2.74%, 2.33% and 1.70%, respectively.

scholarly journals Coupled prediction of flood response and debris flow initiation during warm and cold season events in the Southern Appalachians, USA

2013 ◽  
Vol 10 (7) ◽  
pp. 8365-8419 ◽  
Author(s):  
J. Tao ◽  
A. P. Barros
Keyword(s):  
Slope Stability ◽  
Debris Flow ◽  
Debris Flows ◽  
Warning System ◽  
Cold Season ◽  
Southern Appalachians ◽  
Winter Storm ◽  
Headwater Catchments ◽  
Flood Response ◽  
Debris Flow Initiation

Abstract. Debris flows associated with rainstorms are a frequent and devastating hazard in the Southern Appalachians in the United States. Whereas warm season events are clearly associated with heavy rainfall intensity, the same cannot be said for the cold season events. Instead, there is a relationship between large (cumulative) rainfall events independently of season, and thus hydrometeorological regime, and debris flows. This suggests that the dynamics of subsurface hydrologic processes play an important role as a trigger mechanism, specifically through soil moisture redistribution by interflow. The first objective of this study is to investigate this hypothesis. The second objective is to assess the physical basis for a regional coupled flood prediction and debris flow warning system. For this purpose, uncalibrated model simulations of well-documented debris flows in headwater catchments of the Southern Appalachians using a 3-D surface-groundwater hydrologic model coupled with slope stability models are examined in detail. Specifically, we focus on two vulnerable headwater catchments that experience frequent debris flows, the Big Creek and the Jonathan Creek in the Upper Pigeon River Basin, North Carolina, and three distinct weather systems: an extremely heavy summertime convective storm in 2011; a persistent winter storm lasting several days; and a severe winter storm in 2009. These events were selected due to the optimal availability of rainfall observations, availability of detailed field surveys of the landslides shortly after they occurred, which can be used to evaluate model predictions, and because they are representative of events that cause major economic losses in the region. The model results substantiate that interflow is a useful prognostic of conditions necessary for the initiation of slope instability, and should therefore be considered explicitly in landslide hazard assessments. Moreover, the relationships between slope stability and interflow are strongly modulated by the topography and catchment specific geomorphologic features that determine subsurface flow convergence zones. The three case-studies demonstrate the value of coupled prediction of flood response and debris flow initiation potential in the context of developing a regional hazard warning system.

scholarly journals EVALUATION ON THE IMPLEMENTATION OF EARLY WARNING SYSTEM FOR LAHAR IN MERAPI AREA (CASE STUDY AT BOYONG RIVER)

2015 ◽  
Vol 1 (3) ◽  
pp. 77
Author(s):  
Ali Cahyadi Achmad
Keyword(s):  
Debris Flow ◽  
Qualitative Analysis ◽  
Volcanic Activity ◽  
Early Warning ◽  
Early Warning System ◽  
Rainfall Intensity ◽  
Warning System ◽  
Actual Condition ◽  
Telemetry System ◽  
Debris Flood

One of disasters caused by volcanic activity of Mount Merapi is secondary disaster. The disaster usually occurs after eruption and this volcanic activity produces volcanic and pyroclastic material deposit around the top of the mountain as a result of previous eruption. This material might collapse downward in the form of debris flow as it is affected by natural event such as high intensity rainfall. Therefore, a research is needed to analyze whether existing forecasting and early warning system are capable to provide information for the people living in hazardous area before the debris flood occur. This research was carried out using field survey, observation and interview method. Data analysis used qualitative descriptive method by making description of actual condition of the researched location general condition and qualitative analysis of telemetry system installed on Mount Merapi. The qualitative analysis of telemetry system covers network, hardware, software, power supply, security system, operation and maintenance, also human resources. Research analysis used primary and secondary data. Research results revealed that mean rainfall intensity above of 60 mm/hour might trigger debris flood. Early warning should be given at the rainfall intensity level of 50-55 mm/hour, and debris flood time travel from the upstream to the observed location in Pulowatu Village is 45 minute. Based on the analysis of the present forecasting and early warning system, it is known that some of the equipment is not well functioned, so that debris flow cannot be predicted and detected. This is caused by the lack of human resource quality of the officers in operating and maintaining the equipment. Concerning that matter, it is necessary to conduct some improvement to achieve better forecasting and early warning system in order to give information regarding occurrence of debris flow.

scholarly journals Coupled prediction of flood response and debris flow initiation during warm- and cold-season events in the Southern Appalachians, USA

2014 ◽  
Vol 18 (1) ◽  
pp. 367-388 ◽  
Author(s):  
J. Tao ◽  
A. P. Barros
Keyword(s):  
Slope Stability ◽  
Debris Flow ◽  
Debris Flows ◽  
Warning System ◽  
Cold Season ◽  
Southern Appalachians ◽  
Winter Storm ◽  
Headwater Catchments ◽  
Flood Response ◽  
Debris Flow Initiation

Abstract. Debris flows associated with rainstorms are a frequent and devastating hazard in the Southern Appalachians in the United States. Whereas warm-season events are clearly associated with heavy rainfall intensity, the same cannot be said for the cold-season events. Instead, there is a relationship between large (cumulative) rainfall events independently of season, and thus hydrometeorological regime, and debris flows. This suggests that the dynamics of subsurface hydrologic processes play an important role as a trigger mechanism, specifically through soil moisture redistribution by interflow. We further hypothesize that the transient mass fluxes associated with the temporal-spatial dynamics of interflow govern the timing of shallow landslide initiation, and subsequent debris flow mobilization. The first objective of this study is to investigate this relationship. The second objective is to assess the physical basis for a regional coupled flood prediction and debris flow warning system. For this purpose, uncalibrated model simulations of well-documented debris flows in headwater catchments of the Southern Appalachians using a 3-D surface–groundwater hydrologic model coupled with slope stability models are examined in detail. Specifically, we focus on two vulnerable headwater catchments that experience frequent debris flows, the Big Creek and the Jonathan Creek in the Upper Pigeon River Basin, North Carolina, and three distinct weather systems: an extremely heavy summertime convective storm in 2011; a persistent winter storm lasting several days; and a severe winter storm in 2009. These events were selected due to the optimal availability of rainfall observations; availability of detailed field surveys of the landslides shortly after they occurred, which can be used to evaluate model predictions; and because they are representative of events that cause major economic losses in the region. The model results substantiate that interflow is a useful prognostic of conditions necessary for the initiation of slope instability, and should therefore be considered explicitly in landslide hazard assessments. Moreover, the relationships between slope stability and interflow are strongly modulated by the topography and catchment-specific geomorphologic features that determine subsurface flow convergence zones. The three case studies demonstrate the value of coupled prediction of flood response and debris flow initiation potential in the context of developing a regional hazard warning system.

scholarly journals Determination of the runoff threshold for triggering debris flows in the area affected by the Wenchuan Earthquake

2014 ◽  
Vol 2 (7) ◽  
pp. 4659-4684 ◽  
Author(s):  
P. Cui ◽  
X. J. Guo ◽  
J. Q. Zhuang
Keyword(s):  
Debris Flow ◽  
Wenchuan Earthquake ◽  
Particle Diameter ◽  
Surface Flow ◽  
Flow Density ◽  
Median Particle Diameter ◽  
Flow Formation ◽  
Median Particle ◽  
Runoff Discharge ◽  
Debris Flow Initiation

Abstract. We constructed an experiment to determine the critical runoff discharge for debris flow initiation in Wenchuan Earthquake area. A single dimensionless discharge variable was integrated to incorporate influential parameters, including channel width, median particle diameter, and surface flow discharge. The results revealed that relationship with the debris flow density, slope and discharge required. Taking into account the behaviors of debris flow formation corresponding to different ranges of slopes, the critical runoff thresholds for debris flow initiation were calculated for three different scenarios. The thresholds were validated against actual debris flow events, and the use in this study is applicable.

scholarly journals Community Based Warning and Evacuation System against Debris Flow in the Upper Jeneberang River, Gowa, South Sulawesi

2008 ◽  
Vol 22 (1) ◽  
pp. 13
Author(s):  
Sutikno Hardjosuwarno
Keyword(s):  
Debris Flow ◽  
Reference Point ◽  
Rainfall Intensity ◽  
Arrival Time ◽  
Warning System ◽  
Community Based ◽  
Sediment Volume ◽  
River Terraces ◽  
Hazard Area ◽  
Radio Transceiver

Gigantic collapse of the Caldera wall of Mt. Bawakaraeng (2,830 m) in March 2004 had supplied the sediment volume of 230 million to the most upper stream of Jeneberang River, which flowed down to the lower reach in the form of debris flow which is triggered by rainfall. The purpose of the research is to provide a system which is able to forecast the occurrence of debris flow, to identify the weak points along the river course, to identify the hazard areas and how to inform effectively and efficiently the warning messages to the inhabitants in the dangerous area by using the existing modern equipment combined with the traditional one. The standard rainfall which is used to judge the occurrence of debris flow was established by Yano method. It is based on the historical data of rainfall that trigger and not trigger to the occurrence of debris flow which is widely used in Japan so far. The hazard area was estimated by Two-Dimensional Simulation Model for debris flow, the debris flow arrival time at each point in the river were estimated by dividing their distance from reference point by debris flow velocity, where the check dam no. 7-1 in Manimbahoi was designated as reference point. The existing evacuation routes were checked by field survey, the strength and coverage of sound for kentongan and manual siren were examined using sound pressure level at the location of the existing monitoring post and the effectiveness of warning and evacuation were evaluated by comparing the warning and evacuation time against the debris flow arrival time. It was resulted that debris flow occurrence was triggered by short duration of high rainfall intensity, long duration of low rainfall intensity and the outbreak of natural dam which is formed by land slide or bank collapses. The hazard area of upper Jeneberang River are mostly located on the river terraces where the local inhabitants earn their living through cultivating the river terraces as paddy fields, dry field and sand mining. It was also resulted that at the elevation of 700 m to the upper stream, the arrival time of debris flow is too short (< 3 minutes), it means that there is no time to evacuate when debris flow occurs. There are enough time to evacuate along the reaches between 700 m to 390 m and more time to evacuate along the downstream of 390 m river bed elevation due to the longer arrival time of debris flow. The existing community based warning system against debris flow uses radio transceiver to communicate between post and uses kentongan and sirens to propagate the warning message to inhabitants. Based on the sound test conducted in Jeneberang River, the manual siren has a coverage of 160 m to 600 m and it can be used in the warning system, being co-existence with the kentongan which has been used for a long time. In order to keep the community based warning system well functioned, it is recommended to synergize between the Local Government of Gowa Regency and the other stake holders with the inhabitants along Jeneberang River and the Sabo Community of Jeneberang in the operation and maintenance of the system.

X-MP Radar for Developing a Lahar Rainfall Threshold for the Merapi Volcano Using a Bayesian Approach

2019 ◽  
Vol 14 (5) ◽  
pp. 811-828 ◽  
Author(s):  
Ratih Indri Hapsari ◽  
Satoru Oishi ◽  
Magfira Syarifuddin ◽  
Rosa Andrie Asmara ◽  
Djoko Legono ◽  
...  
Keyword(s):  
Debris Flow ◽  
Warning System ◽  
Rainfall Threshold ◽  
Bayesian Probability ◽  
Good Representation ◽  
Merapi Volcano ◽  
Track Record ◽  
Long Duration ◽  
Short Term Prediction ◽  
Critical Lines

Lahar flow is recognized as among the worst secondary hazards from volcanic disaster. Intense rainfall with long duration is frequently associated with lahar flow. In this study, estimation of a rainfall threshold likely to trigger lahar flow is presented in the first part. The second part discusses its implementation by assessing the growth of observed and predicted rainfall, including the uncertainties. The study area is Merapi Volcano, one of the most active volcanoes in Indonesia, including rivers on the flank of Mount Merapi that are vulnerable to debris flow. The rainfall indices needed to describe the conditions that generate lahars or not were determined empirically by evaluating the hourly and working rainfall using X-band multiparameter (X-MP) weather radar. Using past records of lahar flow, the threshold lines separating rainfall that triggers lahars or not were analyzed for the Putih, Gendol, Pabelan, and Krasak Rivers. The performance of several critical lines was evaluated using Bayesian probability based on skill rates from a contingency matrix. The study shows that the line intercept of the critical lines after a significant eruption in 2010 was higher than those lines developed before 2010, indicating that the rivers are currently at lesser risk. Good representation was shown by the thresholds verified with actual rainfall progression and lahar event information on February 17, 2016, at the Gendol and Pabelan Rivers. These rainfall critical lines were the basis for judging the debris flow occurrence by analyzing the track record of predicted rainfall progression. The uncertainty of rainfall short-term prediction from the extrapolation model was evaluated by perturbing the advection vector of rain echo motion. This ensemble forecast product could provide a plausible range of prediction possibility as assistance in gaining the confidence with which a lahar could be predicted. The scheme presented herein could serve as a useful tool for a lahar early warning system in the area of the Merapi Volcano.

scholarly journals Characteristics of rainfall triggering of debris flows in the Chenyulan watershed, Taiwan

2013 ◽  
Vol 13 (4) ◽  
pp. 1015-1023 ◽  
Author(s):  
J. C. Chen ◽  
C. D. Jan ◽  
W. S. Huang
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Extreme Rainfall ◽  
Field Investigation ◽  
Rainfall Event ◽  
Extreme Rainfall Event ◽  
Rainfall Index ◽  
Hourly Rainfall ◽  
Central Taiwan ◽  
Debris Flow Initiation

Abstract. This paper reports the variation in rainfall characteristics associated with debris flows in the Chenyulan watershed, central Taiwan, between 1963 and 2009. The maximum hourly rainfall Im, the maximum 24 h rainfall Rd, and the rainfall index RI (defined as the product RdIm) were analysed for each rainfall event that triggered a debris flow within the watershed. The corresponding number of debris flows initiated by each rainfall event (N) was also investigated via image analysis and/or field investigation. The relationship between N and RI was analysed. Higher RI of a rainfall event would trigger a larger number of debris flows. This paper also discusses the effects of the Chi-Chi earthquake (CCE) on this relationship and on debris flow initiation. The results showed that the critical RI for debris flow initiation had significant variations and was significantly lower in the years immediately following the CCE of 1999, but appeared to revert to the pre-earthquake condition about five years later. Under the same extreme rainfall event of RI = 365 cm2 h−1, the value of N in the CCE-affected period could be six times larger than that in the non-CCE-affected periods.

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