Mountain Debris Research Articles

Rock glaciers across the United States predominantly accelerate coincident with rise in air temperatures

Despite their extensive global presence and the importance of variations in their speed as an essential climate variable, only about a dozen global time series document long-term changes in the velocity of rock glaciers – large tongue-shaped flows of frozen mountain debris. By analysing historical aerial photographs, we reconstruct here 16 new time series, a type of data that has not previously existed for the North American continent. We observe substantial accelerations, as much as 2–3 fold, in the surface displacement rates of rock glaciers across the mountains of the western contiguous United States over the past six to seven decades, most consistent with strongly increasing air temperatures in that region. Variations between individual time series suggest that different local and internal conditions of the frozen debris bodies modulate this overall climate response. Our observations indicate fundamental long-term environmental changes associated with frozen ground in the study region.

Snowmelt-triggered debris flows in seasonal snowpacks

Snowmelt-triggered debris flows commonly occur in mountains. On 14 June 2019, a debris flow occurred on a steep, east-facing slope composed of unconsolidated glacial and periglacial sediments in Yosemite National Park. Originating as a shallow landslide, ~1,300m3 of ripe snow was instantaneously entrained into the debris flow carrying boulders, trees, and soil downslope. The forested area at the toe of the slope strained out debris leaving a muddy slurry to issue across Highway 120 during dewatering. We document this mass movement and assesses its initiation using local snowpack and meteorological data as well as a regional atmospheric reanalysis to examine synoptic conditions. A multiday warming trend and ripening of the snowpack occurred prior to the event as a 500 hPa ridge amplified over western North America leading to record warm 700 hPa temperatures. Anomalous temperatures and cloud cover prevented refreezing of the snowpack and accelerated its ripening with meltwater contributing to soil saturation. Similar conditions occurred during the catastrophic 1983 Slide Mountain debris flow, also hypothesized to be snowmelt initiated. With projected increases in heat waves, our findings can support natural hazard early warning systems in snow-dominated environments.

Risk Assessment of Debris Flow in a Mountain-Basin Area, Western China

Debris flow risk comprehensively reflects the natural and social properties of debris flow disasters and is composed of the risk of the disaster-causing body and the vulnerability of the carrier. The Bailong River Basin (BRB) is a typical mountainous environment where regional debris flow disasters occur frequently, seriously threatening the lives of residents, infrastructure, and regional ecological security. However, there are few studies on the risk assessment of mountainous debris flow disasters in the BRB. By considering a complete catchment, based on remote sensing and GIS methods, we selected 17 influencing factors, such as area, average slope, lithology, NPP, average annual precipitation, landslide density, river density, fault density, etc. and applied a machine learning algorithm to establish a hazard assessment model. The analysis shows that the Extra Trees model is the most effective for debris flow hazard assessments, with an accuracy rate of 88%. Based on socio-economic data and debris flow disaster survey data, we established a vulnerability assessment model by applying the Contributing Weight Superposition method. We used the product of debris flow hazard and vulnerability to construct a debris flow risk assessment model. The catchments at a very high-risk were distributed mainly in the urban area of Wudu District and the northern part of Tanchang County, that is, areas with relatively dense economic activities and a high disaster frequency. These findings indicate that the assessment results provide scientific support for planning measures to prevent or reduce debris flow hazards. The proposed assessment methods can also be used to provide relevant guidance for a regional risk assessment of debris flows in the BRB and other regions.

Retraction Note: Wireless sensor-based prediction of debris flow in mountainous areas and improvement of power business environment

Abstract This article introduces the composition of the satellite navigation system, the working principle of the receiver, and the Beidou application system and then introduces the system architecture and functions of the wireless sensor network and summarizes the advantages and disadvantages of the two systems in practical applications. On this basis, a fusion system and wireless sensor network based on Beidou are designed. First, the application requirements and system characteristics are clarified, and then the overall architecture of the fusion system is proposed, and the workflow, software, and hardware components of the fusion system are described; then, the integrated system is applied in the actual environment. As a technical support is for the automatic monitoring of mountain debris flow and logistics and transportation. Based on the sedimentary characteristics of the S River study area, it is found that the valley morphology is consistent with the distribution analysis of highway flow, and it is found that there are two types of highway flow in the study area. Finally, this paper conducts a visual analysis of the relevant literature on the improvement of the electricity business environment from 2012 to 2020 in the CNKI database and discusses its current status, evolution, and hot spots in depth. Establish a comprehensive framework for improving the business environment of electricity. The research results show that the research of electricity business has new characteristics of the times. The research field always follows the policy orientation, focusing on simplifying the management and decentralization of electricity and economic development and improving the electricity business environment. Among them, the influencing factors and consequences of electricity business are the core themes of the research.

Rainfall Warning Model for Rainfall-Triggered Channelized Debris Flow Based on Physical Model Test—A Case Study of Laomao Mountain Debris Flow in Dalian City

Debris flows are among the most frequent and hazardous disasters worldwide. Debris flow hazard prediction is an important and effective means of engineering disaster mitigation, and rainfall threshold is the core issue in debris flow prediction. This study selected the Laomao Mountain debris flow in Dalian as the research object and explored the relationship among the percentage of coarse sand content of soil, rainfall conditions and the critical rainfall values that induce debris flows on the basis of field investigation data, combined with the results of a flume test, soil suction measurement and geomechanical analysis. The new multi-parameter debris flow initiation warning models were obtained through the mathematical regression analysis method. The critical rainfall values of debris flows in this area were calculated by the previous research on the mechanism of hydraulic debris flow initiation (HIMM). Lastly, the multi-parameter debris flow initiation warning models were compared and analyzed with the critical rainfall values obtained using the HIMM method and the rainfall information available in historical rainfall data, and the reliability of the models was verified. The comparison results showed that the new multi-parameter debris flow initiation warning models can effectively modify the traditional intensity–duration model and have certain reliability and practical values. They can provide an effectual scientific basis for future work on the monitoring and prediction of debris flow disasters.

Geological And Geotechnical Characterization Of The Beni Moussa Perimeter In The Tadla Plain(Morocco)

The Beni Moussa perimeter in the plain of Tadla is located in the Beni Mellal - Khenifra region characterized by the diversity of its relief where the mountain meets the plain through the foothills. Bibliographic studies raise the dominance of limestone formations in the Atlas ranges of this region, and the piedmont accumulates alluvium deposited by rivers, while the plain is filled with mio-plio-quaternary deposits. A series of seven drill holes of various depths, supplemented by pressuremeter measurements every 1.50m of depth using the Menard pressuremeter, was carried out on sites scattered around the perimeter of the Beni Moussa in the plain of Tadla, to validate at first the bibliographic geological models, then to appreciate the bearing capacity of the lithologies revealed. The lithological sections thus revealed an alternation of alluvial deposits, clays and clay loams, deposited on calcareous formations, resulting from the dolomitic and calcareous mountainous debris mobilized following the seasonal temperature’s variation of the region. Moreover, the measured pressurometric ranges characterize a generally high bearing capacity, and reflect the generalized overconsolidation of the facies and soils encountered in the Beni Moussa area, except for the Middle Pleistocene formations, which are mainly characterized by channeled conglomeratic deposits.This study’s datathus reflect a good bearing capacity of the ground formations, capable of supporting the superstructures founded in this perimeter.

Experimental and numerical study on the load and deformation mechanism of a flexible net barrier under debris flow impact

High-strength flexible net barriers have achieved a certain effect in mountainous debris flow prevention, but research on the mechanism of structural stress and deformation is still developing. This study first presents an analytical model based on the quasi-static mechanical equilibrium to evaluate the geometric nonlinearity and the load performance of the structure and then conducts a flume experiment to reveal the load mechanism of the structure. Then, a full-scale simulation is performed to investigate the deformation and failure of the flexible net barrier impacted by the debris flow via PFC3D software. The results show that the deformation of the flexible net barrier occurs not only in the direction of flow but also in other directions to make the structure force balanced under debris flow impact. The load impacting on the barrier is far less than the total impact force exerted by debris flow. The flexible barrier has an obvious effect to block a coarse debris flow, and the blocking capacity is related to the volume of debris flow and the slope gradient of the flume. The displacement patterns of loaded cable in the experiment and the simulation are different, but the cable under non-debris flow impact is only dragged by the mesh rope showing a regular parabolic shape, and the tension inside the flexible mesh is far less than that of the transverse cable. In addition, the model shows the failure characteristics of flexible barrier under large-scale debris flow, which plays a guiding role in practical engineering design of the structure.

Implementation of a landscape ecological use pattern model: Debris flow waste-shoal land use in the Yeyatang Basin, Yunnan Province, China

Debris flow waste-shoal land (DFWSL) is a significant and potential land resource that is largely ignored in ecologically fragile mountainous areas. Yeyatang Basin, in Yunnan Province, China, is a typical mountainous debris flow area with a large amount of DFWSL. In order to achieve efficient use of DFWSL in this area, we built a demonstration plot and implemented a landscape ecological use pattern (LEUP) model for the DFWSL, with which we analyzed the economic, ecological, and social benefits. The results showed that the LEUP significantly improved incomes and vegetation coverage, and it reduced soil and water loss, controlled the debris flow, and ensured the safety of residents. To some extent, the LEUP alleviated the conflict between socioeconomic development and environmental protection and increased local employment opportunities, which could help to resolve the socioeconomic issues associated with rural hollow villages and left-behind children. The model demonstration results will provide a “road map” to wasteland use and serve as an important information resource for policymakers. Leaders should consider shifting their perspectives toward exploring land resources that had previously been deemed unavailable and pay more attention to the management and development of DFWSL, which could potentially enable the sustainable development of mountain ecosystems and economies, and enhance the prevention and control of natural disasters in mountainous regions.

Identification of debris-flow hazards in warm deserts through analyzing past occurrences: Case study in South Mountain, Sonoran Desert, USA

After recognition that debris flows co-occur with human activities, the next step in a hazards analysis involves estimating debris-flow probability. Prior research published in this journal in 2010 used varnish microlamination (VML) dating to determine a minimum occurrence of 5 flows per century over the last 8100years in a small mountain range of South Mountain adjacent to neighborhoods of Phoenix, Arizona. This analysis led to the conclusion that debris flows originating in small mountain ranges in arid regions like the Sonoran Desert could pose a hazard. Two major precipitation events in the summer of 2014 generated 35 debris flows in the same study area of South Mountain—providing support for the importance of probability analysis as a key step in a hazards analysis in warm desert settings. Two distinct mechanisms generated the 2014 debris flows: intense precipitation on steep slopes in the first storm; and a firehose effect whereby runoff from the second storm was funneled rapidly by cleaned-out debris-flow chutes to remobilize Pleistocene debris-flow deposits. When compared to a global database on debris flows, the 2014 storms were among the most intense to generate desert debris flows — indicating that storms of lesser intensity are capable of generating debris flows in warm desert settings. The 87Sr/86Sr analyses of fines and clasts in South Mountain debris flows of different ages reveal that desert dust supplies the fines. Thus, wetter climatic periods of intense rock decay are not needed to resupply desert slopes with fines; instead, a combination of dust deposition supplying fines and dirt cracking generating coarse clasts can re-arm chutes in a warm desert setting with abundant dust.

Experimental and numerical study on the design of a deposition basin outlet structure at a mountain debris cone

Abstract. Mountain debris cones in the Alpine region often provide space for dense population and cultivation. Hence, a great number of buildings are exposed to torrential hazards. In order to protect the settlement areas against flooding and overbank sedimentation, torrent defence structures are implemented at various locations within catchments. Directly at the debris cones, these protection measures often include a deposition basin at the fan apex and/or a confined channel that passes through the settlement. The work presented within this paper deals with the effect of specific outlet structure layouts, situated at the lower end of a selected deposition basin, on bed-load transport processes and flood protection. A case study analysis was accomplished comprising a 3-D numerical model (FLOW-3D) and a physical scale model test (1 : 30). The subject of investigation was the deposition basin of the Larsennbach torrent in the Austrian Northern Limestone Alps. The basin is situated on a large debris cone and opens out into a paved channel. Since the basin is undersized and the accumulation of sediment in the outlet section reduces the available cross section during floods, adjoining settlements are considerably endangered of lateral overtopping of both clear water and sediment. Aiming for an upgrade in flood protection, certain layouts for a "closing-off structure" at the outlet were tested within this project. For the most efficient design layout, its effect on flood protection, a continuous bed-load output from the basin and the best possible use of the retention volume are pointed out. The simple design of the structure and the key aspects that have to be taken into consideration for implementation are highlighted.

유하부 지형 특성에 따른 토석류 퇴적 분석

최근 우리나라에서는 극한 강우 조건에서 발생하게 되는 토석류의 발생 빈도가 증가하고 있다. 본 논문에서는 유하부의 지형 특성에 따른 토석류 퇴적의 발생 특성을 분석하는 방법을 기술하였다. 먼저 토석류 발생 전후 비교적 근시기의 고해상도 LiDAR DEM을 차분하여 지형변화를 관측하고, 유하부 외부로의 퇴적이 관측되는 지점을 토석류의 관성으로 인해 토석류 이동이 진행된 지점으로 가정한 후, 이러한 퇴적이 발생하는 유하부의 지형 특성을 유로방향경사, 유하부의 이동 전환각도, 발생부로부터 해당 지점까지의 이동거리에 대한 표고차의 비율계수(L/H)로 표현되는 토석류의 순효율 계수 특성 항목을 이용하여 분석을 수행하였다. 이러한 방법을 2011년 7월 발생한 우면산 토석류 재해를 대상으로 하여 실험을 수행하였다. 실험결과 관성에 의한 토석류의 퇴적은 유하부의 전환각도와 큰 상관관계를 갖는 것으로 나타났으며, '전환각도/(L/H)'의 비율이 8 이상인 지점에서 관성에 의한 진행이 주로 발생함을 알 수 있었다. Recently, the frequency of debris flow disaster has increased, which is one of the natural disasters during extremely heavy rainfall condition. This paper described the analysis method about deposition characteristics of debris flow using topographic characteristics of debris flow path. First, we observed topographic changes by differencing high- resolution LiDAR DEMs acquired before and after the occurrence of debris flow event. We assumed that deposition on outside of debris flow path was generated by movements due to the inertia of debris flows. Then, we analyzed three topographic characteristics of debris flow path: slope in flow direction, transition angle of flow path, and the net efficiency(L/H) of debris flows defined by the ratio of transport length(L) and elevation difference(H). We applied this method to Umyeon Mountain debris flow event in July 2011. The results showed that deposition on outside of debris flow path due to the inertia of debris flows was significantly related to the transition angle of debris flow path. Also, we figured out that there were more frequent such depositions in locations where the ratio of 'transition angle / (L/H)' is over 8.

Estimating the size and travel distance of Klapperhorn Mountain debris flows for risk analysis along railway, Canada

Debris flows occurring on Klapperhorn Mountain in the Yellowhead Pass in the Canadian Rocky Mountains pose a significant hazard to railway operations at the base of the mountain. The size (volume) and travel distance of these debris flows play an important role in assessing the risk to the railway. GIS analysis, airphoto interpretation together with field work were undertaken on two debris flows located at track mileage 54.0 and 54.3. Characteristics of these two debris flow events were analyzed, including debris flow path morphology and event behavior. Their sizes and travel distances were estimated using an empirical-statistical model (UBCDFLOW) under different initiation conditions. Their potential impact on the railway bridge was evaluated using a bridge blockage ratio.

Health and the Environment after Hurricane Katrina

Health and the Environment after Hurricane Katrina

Flow behavior of debris flows in the upper stream on mountainous debris torrent

Flow behavior of debris flows in the upper stream on mountainous debris torrent

Observation of the formation and dynamic process of debris flows in a mountainous debris torrent

Observation of the formation and dynamic process of debris flows in a mountainous debris torrent

Cathedral mountain debris flows, Canada : Jackson, L E; Hungr, O; Gardner, J S; Mackay, C Int Assoc Engng Geol BullN40, Oct 1989, P35–54

Cathedral mountain debris flows, Canada : Jackson, L E; Hungr, O; Gardner, J S; Mackay, C Int Assoc Engng Geol BullN40, Oct 1989, P35–54

Cathedral Mountain debris flows, Canada

Historic debris flow activity along the north side of Cathedral Mountain in the southern Rocky Mountains of British Columbia, began in 1925 and has increased in frequency up to 1985. A typical debris flow event involves approximately 100,000 m3 of material. Debris flow velocities and discharges above the head of the fan crossed by the Trans-Canada Highway and the C.P.R. mainline are 5.5 m/sec and 210 m3/sec. Most of the large debris flow events are associated with jokulhlaups from Cathedral Glacier. Jokulhlaup discharges of at least 10,000 and perhaps as much as 24,000 m3 of water mobilize these debris flows. Part of the water may have come from a small ephemeral lake on the south side of the glacier. The balance must have been stored within the glacier. The onset and acceleration of debris flow activity was apparently induced by the recession of Cathedral Glacier. Source areas of debris flow sediments have retreated upslope since initiation of debris flow activity. C.P.R. began pumping meltwater from the glacier in 1985 and no jokulhlaups or significant debris flows have occurred since. This preventive measure should either eliminate jokulhlaups or reduce their magnitudes should they occur. Without jokulhlaups, debris flow hazard in the area should be reduced both in frequency and in magnitude.

PARTICLE SIZE AND SHAPE VARIATION ON ALPINE DEBRIS FANS, CANADIAN ROCKY MOUNTAINS

Much of the previous research on mountain debris slopes has focused on slopes of avalanche and, especially, rockfall origin. This study examines particle size and shape variation on some debris fans formed by rockfall, snow avalanches, and stream-debris flow on dissected rockwalls. The particle size and shape data are derived from the lengths of the 3 principal axes of 50 particles sampled at 152 stops on 24 transects. The analysis of these data indicates that variation in particle shape is a function of source rock lithology while particle size varies according to the process of coarse debris transfer. Most of the size variation occurs at the sampling stops and among stops within transects. Size means and variances differ according to process for samples not affected by stream-debris flow. Second-order polynomial regressions depict the longitudinal size sorting produced by each process and reflect the unique nature of debris transfer on dissected rockwalls, where rockfall is impeded and debris is sequent...