scholarly journals Recognition of debris flow, debris flood and flood hazard through watershed morphometrics

Landslides ◽  
2004 ◽  
Vol 1 (1) ◽  
pp. 61-66 ◽  
Author(s):  
D. J. Wilford ◽  
M. E. Sakals ◽  
J. L. Innes ◽  
R. C. Sidle ◽  
W. A. Bergerud
Keyword(s):  
Debris Flow ◽  
Flood Hazard ◽  
Debris Flood

scholarly journals Observations on the May 2019 Joffre Peak landslides, British Columbia

Landslides ◽  
2020 ◽  
Vol 17 (4) ◽  
pp. 913-930 ◽  
Author(s):  
Pierre Friele ◽  
Tom H. Millard ◽  
Andrew Mitchell ◽  
Kate E. Allstadt ◽  
Brian Menounos ◽  
...  
Keyword(s):  
British Columbia ◽  
Debris Flow ◽  
Seismic Analysis ◽  
Rock Avalanche ◽  
Permafrost Degradation ◽  
Depth Estimate ◽  
Coast Mountains ◽  
Conditioning Factors ◽  
The North ◽  
Debris Flood

AbstractTwo catastrophic landslides occurred in quick succession on 13 and 16 May 2019, from the north face of Joffre Peak, Cerise Creek, southern Coast Mountains, British Columbia. With headscarps at 2560 m and 2690 m elevation, both began as rock avalanches, rapidly transforming into debris flows along middle Cerise Creek, and finally into debris floods affecting the fan. Beyond the fan margin, a flood surge on Cayoosh Creek reached bankfull and attenuated rapidly downstream; only fine sediment reached Duffey Lake. The toe of the main debris flow deposit reached 4 km from the headscarp, with a travel angle of 0.28, while the debris flood phase reached the fan margin 5.9 km downstream, with a travel angle of 0.22. Photogrammetry indicates the source volume of each event is 2–3 Mm3, with combined volume of 5 Mm3. Lidar differencing, used to assess deposit volume, yielded a similar total result, although error in the depth estimate introduced large volume error masking the expected increase due to dilation and entrainment. The average velocity of the rock avalanche-debris flow phases, from seismic analysis, was ~ 25–30 m/s, and the velocity of the 16 May debris flood on the upper fan, from super-elevation and boulder sizes, was 5–10 m/s. The volume of debris deposited on the fan was ~ 104 m3, 2 orders of magnitude less than the avalanche/debris flow phases. Progressive glacier retreat and permafrost degradation were likely the conditioning factors; precursor rockfall activity was noted at least ~6 months previous; thus, the mountain was primed to fail. The 13 May landslide was apparently triggered by rapid snowmelt, with debuttressing triggering the 16 May event.

scholarly journals Regional debris flow susceptibility analysis in mountainous peri-urban areas through morphometric and land cover indicators

2014 ◽  
Vol 14 (11) ◽  
pp. 3043-3064 ◽  
Author(s):  
M. C. Rogelis ◽  
M. Werner
Keyword(s):  
Land Cover ◽  
Debris Flow ◽  
Flood Risk ◽  
Urban Areas ◽  
Debris Flows ◽  
Flood Hazard ◽  
Flow Direction ◽  
Hazard Analysis ◽  
Principal Component ◽  
Debris Flow Susceptibility

Abstract. A method for assessing regional debris flow susceptibility at the watershed scale, based on an index composed of a morphometric indicator and a land cover indicator, is proposed and applied in 106 peri-urban mountainous watersheds in Bogotá, Colombia. The indicator of debris flow susceptibility is obtained from readily available information common to most peri-urban mountainous areas and can be used to prioritise watersheds that can subsequently be subjected to detailed hazard analysis. Susceptibility is considered to increase with flashiness and the possibility of debris flows occurring. Morphological variables recognised in the literature to significantly influence flashiness and occurrence of debris flows are used to construct the morphometric indicator by applying principal component analysis. Subsequently, this indicator is compared with the results of debris flow propagation to assess its capacity in identifying the morphological conditions of a watershed that make it able to transport debris flows. Propagation of debris flows was carried out using the Modified Single Flow Direction algorithm, following identification of source areas by applying thresholds identified in the slope–area curve of the watersheds. Results show that the morphometric variables can be grouped into four indicators: size, shape, hypsometry and (potential) energy, with energy being the component that best explains the capability of a watershed to transport debris flows. However, the morphometric indicator was found to not sufficiently explain the records of past floods in the study area. Combining the morphometric indicator with land cover indicators improved the agreement and provided a more reliable assessment of debris flow susceptibility in the study area. The analysis shows that, even if morphometric parameters identify a high disposition to the occurrence of debris flow, improving land cover can reduce the susceptibility. However, if favourable morphometric conditions are present but deterioration of the land cover in the watershed takes place, then the susceptibility to debris flow events increases. The indicator of debris flow susceptibility is useful in the identification of flood type, which is a crucial step in flood risk assessment especially in mountainous environments, and it can be used as input for prioritisation of flood risk management strategies at regional level and for the prioritisation and identification of detailed flood hazard analysis. The indicator is regional in scope, and therefore it is not intended to constitute a detailed assessment but to highlight watersheds that could potentially be more susceptible to damaging floods than others in the same region.

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 Quantitative Prediction of Outburst Flood Hazard of the Zhouqu “8.8” Debris Flow-Barrier Dam in Western China

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 639
Author(s):  
Heyi Yang ◽  
Guan Chen ◽  
Yan Chong ◽  
Jiacheng Jin ◽  
Wei Shi
Keyword(s):  
Water Resources ◽  
Debris Flow ◽  
Flood Hazard ◽  
Peak Discharge ◽  
Western China ◽  
Dam Failure ◽  
Quantitative Prediction ◽  
Outburst Flood ◽  
Dam Breach ◽  
Barrier Dam

In recent years, the intensified influences of global climate change and human activities have increased the frequency of large-scale debris flow disasters. As a result, main river channels often become blocked, thus forming a disaster chain of rivers dammed by debris flow followed by outburst flooding. In order to quickly and easily reveal the dynamic process of a debris flow dam breach, and quantitatively predict the outburst flood hazard, this study takes the Zhouqu “8.8” debris flow barrier dam in Western China as an example. Based on a stability assessment, China Institute of Water Resources and Hydropower Research’s Dam Breach Slope (DBS-IWHR), China Institute of Water Resources and Hydropower Research’s Dam Breach (DB-IWHR), and Hydrologic Engineering Center’s River Analysis System (HEC-RAS) were integrated to simulate the development of dam breach, breach flood, and outburst flood evolution, respectively, under different scenarios. The simulated peak discharge flow of the actual spillway was 317.15 m3/s, which was consistent with the actual discharge of 316 m3/s. The results under different scenarios showed that, with the increased inflow of the barrier lake, the erosion rate of the dam increased, the peak discharge of the dam break flood increased, the peak arrival time shortened, and the downstream flooding area increased. These findings could provide scientific support for risk management and emergency decision-making with respect to barrier dam failure.

Regional debris‐flow and debris‐flood frequency–magnitude relationships

2020 ◽  
Vol 45 (12) ◽  
pp. 2954-2964
Author(s):  
Matthias Jakob ◽  
Emily Mark ◽  
Scott McDougall ◽  
Pierre Friele ◽  
Carie‐Ann Lau ◽  
...  
Keyword(s):  
Debris Flow ◽  
Flood Frequency ◽  
Debris Flood ◽  
Frequency Magnitude

scholarly journals Debris flood hazard documentation and mitigation on the Tilcara alluvial fan (Quebrada de Humahuaca, Jujuy province, North-West Argentina)

2012 ◽  
Vol 12 (6) ◽  
pp. 1873-1882 ◽  
Author(s):  
G. Marcato ◽  
G. Bossi ◽  
F. Rivelli ◽  
L. Borgatti
Keyword(s):  
Risk Mitigation ◽  
Flood Hazard ◽  
Rio Grande ◽  
Tourism Industry ◽  
Alluvial Fan ◽  
Mitigation Strategies ◽  
Mitigation Measures ◽  
North West ◽  
Hazard And Risk ◽  
Debris Flood

Abstract. For some decades, mass wasting processes such as landslides and debris floods have been threatening villages and transportation routes in the Rio Grande Valley, named Quebrada de Humauhuaca. One of the most significant examples is the urban area of Tilcara, built on a large alluvial fan. In recent years, debris flood phenomena have been triggered in the tributary valley of the Huasamayo Stream and reached the alluvial fan on a decadal basis. In view of proper development of the area, hazard and risk assessment together with risk mitigation strategies are of paramount importance. The need is urgent also because the Quebrada de Humahuaca was recently included in the UNESCO World Cultural Heritage. Therefore, the growing tourism industry may lead to uncontrolled exploitation and urbanization of the valley, with a consequent increase of the vulnerability of the elements exposed to risk. In this context, structural and non structural mitigation measures not only have to be based on the understanding of natural processes, but also have to consider environmental and sociological factors that could hinder the effectiveness of the countermeasure works. The hydrogeological processes are described with reference to present-day hazard and risk conditions. Considering the socio-economic context, some possible interventions are outlined, which encompass budget constraints and local practices. One viable solution would be to build a protecting dam upstream of the fan apex and an artificial channel, in order to divert the floodwaters in a gully that would then convey water and sediments into the Rio Grande, some kilometers downstream of Tilcara. The proposed remedial measures should employ easily available and relatively cheap technologies and local workers, incorporating low environmental and visual impacts issues, in order to ensure both the future conservation of the site and its safe exploitation for inhabitants and tourists.

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