Primary structures of granite and following weathering schemes define landslide behavior in granite areas.

Mass movement mapping for geomorphological understanding and sustainable development: Tigray, Ethiopia

This paper describes how debris flows are natural hazards that look like a combination of flood, land and rock slide. The phenomenon is also called mud or debris avalanche because similar flow behavior is compared with snow avalanches. Debris flows regularly cause severe damages in mountainous areas like the Alps. Like rock fall, the debris flows loads act mainly on a protection barrier. But in contrast to falling rocks, debris flows are not punctual impacts but a distributed load on the protection system. A further difference between the two hazards is the fact that rockfalls are single events while debris flows mostly occur in surges. Experiences from North America, Japan and Europe prove that flexible protection systems like the Geobrugg VX/UX Systems have an ideal bearing behavior to stop dynamic loads such as debris flows because of their large deformation capacity

<p>Over the last decades climate has warmed up worldwide and changes have occurred in the general weather patterns. Where the increase in temperature has rapidly been gathering pace in the last decade. These changes have also been observed in Iceland. From 1980 to 2015 the average temperature increase has been 0,47°C per decade and the average precipitation has increased from 1500 mm/year to around 1600-1700 mm/year. The increased temperature changes have also resulted in more frequent thawing periods and rainfall events during winter months, especially in the lowlands.</p><p>Mass movements, including rock falls, rock avalanches, debris flows and debris slides, are common geomorphological processes in Iceland and thus present a significant and direct threat to many towns, villages, and farmhouses. Weather conditions, e.g. precipitation and temperature variations, and earthquake activity are the most common triggering factors for such activity in Iceland. During the last decades several, somewhat unusual, mass movements events have occurred in the island. These events have been unusual both regarding their size, increased frequency, their triggering factors and not at least the timing within the year they have occurred.</p><p>One of the most visible consequence of temperature rise in Iceland is the fast retreat and thinning of outlet glaciers and formation of proglacial lakes. The frequency of mass movements on outlet glaciers have increased considerably from the turn of the century compared to the last 4 decades of the 20<sup>th</sup> century. New discoveries of unstable slopes above outlet glaciers have also increased considerably from 2000.</p><p>In recent years, there has been an increasing interest worldwide in the influence of climate warming and possible decline of mountain permafrost on the occurrence of mass wasting phenomena. The rising frequency of rapid mass movements, such as debris flows, debris slides, rock falls and rock avalanches, in mountainous areas have been linked with mountain permafrost degradation. Several mass movements, which can be connected to thawing of mountain permafrost, have occurred in central N and NW parts of the island during the last decade.</p><p>Majority of landslides in Iceland in the past century have either occurred in relations with low-pressures systems that pass-through Iceland from August to November, bringing in high winds with heavy rainfall, or during spring snowmelt in May and June. But in the past two decades snowmelt and thawing periods are becoming more frequent and longer during wintertime resulting in higher frequency of slope failures during that time of year. Over the past 20 years’ large landslides events (> 300.000 m<sup>3</sup>) have become more frequent compared to the second half of the 20<sup>th</sup> century. </p><p>Climate change certainly seems to be affecting slope stability in Iceland and is an increasing risk. Especially slopes close to retreating glaciers and those affected by thawing of mountain permafrost. Changes in temperature and precipitation patterns in late fall and during winter months are causing slope failures that were not as common in the past. </p>

Debris flow was mass movement such as; clay, fine sand, organic waste and coarse material such as; gravel, rocks, organic waste, logs mixed with water. Based on historical information the slope of the ancient caldera of Mount Batur that were potentially threatened for the village with debris flows hazards including; Trunyan, Abang Batudinding and Buahan Village. Modeling with DFLOWZ software was supported by spatial data with input parameters namely; Digital Elevation Model (DEM) data and Polyline data. Modeling was an initial approach in predicting the debris inundation area. Research results to get the type of material and debris flow direction. The observed flow anatomy was debris flow in valleys and rivers at an altitude of ± 1500 msl, curved in the valleys of the hills and the direction of flow is to the west. The DFLOWZ analysis shows that the retained deposit area that has the potential to cause debris avalanches is 49,830 m2, with an inundation height based on 5-7 m thick slope valley. The results of the modeling serve as a form of early warning for communities affected by the threat of inundation of debris flows.

Research Article| July 01, 1990 Fluvial response to debris associated with mass wasting during extreme floods Andrew J. Miller Andrew J. Miller 1Department of Geography, University of Maryland, Baltimore County, Baltimore, Maryland 21228 Search for other works by this author on: GSW Google Scholar Author and Article Information Andrew J. Miller 1Department of Geography, University of Maryland, Baltimore County, Baltimore, Maryland 21228 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1990) 18 (7): 599–602. https://doi.org/10.1130/0091-7613(1990)018<0599:FRTDAW>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Andrew J. Miller; Fluvial response to debris associated with mass wasting during extreme floods. Geology 1990;; 18 (7): 599–602. doi: https://doi.org/10.1130/0091-7613(1990)018<0599:FRTDAW>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Evolution of channels and bottomlands in mountain valleys of the central Appalachians is strongly influenced by debris supplied to stream channels from mass wasting during extreme storms. The type of change observed varies with basin scale and storm characteristics. Along channels receiving coarse sediment from debris avalanches or debris flows during Hurricane Camille in 1969, pure scour occurred in drainage areas less than 1 km2 and gradients steeper than 0.1; in Hurricane Camille and in the June 1949 storm, mixed erosion and deposition with continuous reworking of the valley floor was observed along streams with drainage areas up to 65 km2. In basins larger than 100 km2, valley-floor reworking associated with influx of debris during both storms was localized and discontinuous.In the South Branch Potomac River basin in West Virginia, intense precipitation within a small contributing area generated scores of debris slides and avalanches in June 1949; debris transported by tributaries to main valleys exceeded the competence of the larger channels and formed new bottomland. Long-duration moderate-intensity precipitation in November 1985 generated fewer debris avalanches. Flood peaks associated with a larger contributing area along the main valleys were 80% to 190% larger than in 1949 and caused extensive channel and flood-plain erosion, including truncation and removal of 1949 deposits. At some locations relict debris deposits may have influenced hydraulic conditions and affected patterns of erosion and deposition during the 1985 storm. Sequential occurrence of extreme storms with different hydrologic characteristics creates a bottomland mosaic of surfaces with varying elevations and textures. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Epiclastic volcanic debrites-evidence of flow transformations between avalanche and debris flow processes, Middle Ordovician, Baie Verte Peninsula, Newfoundland, Canada

Volumes of erosional and depositional landforms were estimated by reconnaissance methods in a steep, forested drainage basin in the Coast Mountains, British Columbia, to examine what insight might be gained into the sediment budget in the absence of direct measurements of sediment transfer processes. Sediment transfers in postglacial and contemporary time were inferred on hillslopes, from hillslopes to stream channels, and within stream channels. Data were collected by aerial photographic analysis and field observation. Postglacial sediment sources are major gullies created by debris slides and flows, failures in glaciolacustrine terraces, and stream channel degradation. Depositional landforms consist of talus slopes and colluvial and alluvial fans. Contemporary sediment sources include debris slides and flows in established gullies and minor processes on hillslopes. Debris slide and debris flow volumes were calculated, and other processes were estimated from regional values. Erosion rate averaged over postglacial time is 276 t·km–2·a–1(0.15 mm·a–1surface lowering), with gullies and stream channel degradation contributing 170 and 82 t·km–2·a–1, respectively. A terminal alluvial fan provides an independent check of the results. In contemporary time, erosion rates are calculated to be 350 t·km–2·a–1, with debris flows and slides contributing nearly all of this sediment. The contemporary rate is probably perturbed by recent land use history. Mass-movement processes appear to be the dominant mechanism of sediment transfer and, contributions from Pleistocene valley deposits have declined significantly during Holocene time.

Modelling the space–time evolution of bed entrainment for flow-like landslides

Soils on steep slopes tend to be unstable due to natural and anthropogenic causes. The natural features of steep slopes that make them susceptible to failures and mass movement are gradient and shape of slope, geology, soil, vegetation and climate. Soils are more prone to mass movement in shallow and loose soils on impervious substratum, on steeper slopes, and under high intensity storms. The human actions that make soils on steep slopes unstable include development, settlement, shifting cultivation, deforestation, forest fires, soil mining, and other slope disturbances. Mass movement or landslides, which occur due to gravity, water saturation and water movement, have several forms: falls, creeps, slumps and earthflows, debris avalanches and debris flows, debris torrents and bedrock failures. These movements have on-site and off-site effects on properties, installations, house-holds, communications, crops, human lives and environmental health. Soils on steep slopes can be stabilized; or in other words, soil erosion in steeply sloping lands can be reduced by several mechanical, agronomic and agroforestry measures. Mechanical measures include drainage, contour bunds, silt fences, surface mats, grading and terracing, retention walls, slope reshaping, etc. Agronomic practices include contour cropping, contour strip cropping; and agroforestry methods are contour hedgerows, alley cropping and sloping agricultural land technology.

&amp;lt;p&amp;gt;Incised valleys or steep slopes in tectonic active mountain areas are normally in a critical equilibrium state which is highly fragile and prone to deviate under exotic disturbances (e.g., earthquake, heavy precipitation, or even human activities), inducing mass movements (e.g., landslides, avalanche, and/or debris flows). Mass movements have great impacts on fluvial processes and may even reshape valley morphology, hence are powerful drivers to river evolution in those environments. Unfortunately, compared to the mass movements themselves (e.g., occurrence time, volume, dynamics and underlying mechanisms), less attention has been paid to the fluvial processes (in a short/intermediate-term) and the long-term evolution of river morphology corresponding to (and after) those mass movements (especially catastrophic ones). This motivates the current work.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;The southeast Tibet, located on the east Qinghai-Tibet Plateau, is one of the most active regions globally in terms of tectonic motion and rates of uplift. Rivers in the lower Yalung Tsangpo basin in this area are investigated to understand the morphodynamics influenced by modern and historical mass movements and examine the feedbacks of fluvial processes to mass movements. River reaches influenced by typical mass movements were chosen for detailed field surveys, including: (1) the upper part of the Yalung Tsangpo Grand Canyon which has been seriously impacted by avalanches and debris flows from tributary gullies originating at glacial mountains of Namcha Barwa and Gyala Peri; (2) the lower reach of the Yigong River covering the Yigong Landslide from the Zhamunong Gully; (3) the lower reach of the Palong River influenced by debris flows from Guxiang and Tianmo gullies; and (4)&amp;amp;#160; the upper and middle reaches of the Palong River (extending roughly from Ranwu Lake to the upstream of Guxiang Lake) influenced by glacial processes and other induced mass movements since the last glacial maximum. Remote sensing images before and after the large-scale mass movements in recent decades were also used to track the corresponding river morphology variation.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;Due to very high transport rate and volume of sediment incoming, mass movements have caused dramatic channel processes in east Tibet. Some even dammed the river, forming knickpoints and reshaping valley morphology. The morphology of the valleys in this area normally show alternating sections of gorges and wide valleys, with a staircase-like longitudinal profile. The gorge sections exhibit single and deeply incised channels with a high-gradient channel bed and terraces. In contrast, the wide valley sections consist of lakes, braided or anabranching channels, gentle bed gradients, and thick alluvial deposits. In recent decades, mass movements (mostly debris flows), occurred more frequently through gullies in the reaches of gorge sections than through gullies along the wide valley sections. Mass movements deviate river morphology and slope from (quasi-)equilibrium to non-equilibrium state, however, with attendant rapid sediment incoming, valley bottom siltation and erosion benchmark rising, it triggers a negative feedback which drives the river morphology to a new round of development towards equilibrium.&amp;lt;/p&amp;gt;

This study investigates community-based landslide mitigation planning. The combination of a landslide susceptibility index (LSI) model, landslide inventory datasets, and field work is used to identify hazard-prone areas in Maolin District, Taiwan. Furthermore, to identify the challenges and opportunities affecting the sustainable development of mountain communities, a pilot survey was conducted in three such communities (Dona Village, Wanshan Village, and Maolin Village). The results reveal that there are two types of significant mass movement in such areas: debris avalanche and debris flow. The results also show that the LSI map and multi-temporal landslide inventory datasets correlate with landslide locations. Meander is identified as an important factor in landslide activity. The questionnaire results show that the residents of the study area lack awareness of and access to information related to landslide activity. Similarly, the local residents favor increased environmental protection, working within their community, and additional government spending in regard to managing geohazards. To increase the resilience of the community, an improved landslide susceptibility map is proposed based on the output of the results. Thus, this research improves upon the process of identifying, supporting, and bettering the management of communities prone to landslides.

Site effects modelling applied to the slope affected by the Suusamyr earthquake (Kyrgyzstan, 1992)

Postfire erosional processes in the Pacific Northwest and Rocky Mountain regions

Abstract. This study compares documented debris flow runout distances with numerical simulations in the Yosemite Valley of California, USA, where about 15% of historical events of slope instability can be classified as debris flows and debris slides (Wieczorek and Snyder, 2004). To model debris flows in the Yosemite Valley, we selected six streams with evidence of historical debris flows; three of the debris flow deposits have single channels, and the other three split their pattern in the fan area into two or more channels. From field observations all of the debris flows involved coarse material, with only very small clay content. We applied the one dimensional DAN (Dynamic ANalysis) model (Hungr, 1995) and the two-dimensional FLO-2D model (O'Brien et al., 1993) to predict and compare the runout distance and the velocity of the debris flows observed in the study area. As a first step, we calibrated the parameters for the two softwares through the back analysis of three debris- flows channels using a trial-and-error procedure starting with values suggested in the literature. In the second step we applied the selected values to the other channels, in order to evaluate their predictive capabilities. After parameter calibration using three debris flows we obtained results similar to field observations We also obtained a good agreement between the two models for velocities. Both models are strongly influenced by topography: we used the 30 m cell size DTM available for the study area, that is probably not accurate enough for a highly detailed analysis, but it can be sufficient for a first screening.

Well‐developed tors and associated boulder fields are present in exposed granitoid pluton, but their geomorphological origins have not been fully addressed. Although the tor‐like features are commonly attributed to the orthogonal joint system along which weathering proceeds and the weathering materials are removed, the majority of previous studies lack three‐dimensional (3‐D) morphological observations. One of the well‐known granitoid rock towers in Japan, namely, the obelisk at Mt. Jizogadake in the Japanese Southern Alps, was investigated using unmanned air vehicles (UAVs). A 3‐D observation of the granitoid obelisk found that it is shaped by columnar joints with an undulation along a long axis and irregularly shaped cross‐sections. Because of these features and intersection angles between the rock columns and exposure surfaces, the obelisk exhibits a peculiar morphology appearing as a heap of rock blocks when observed from the ground. The columnar jointing might have occurred in a marginal zone of the granitoid pluton due to faster cooling rates. The 3‐D observations also confirmed the columnar joints formation was predated by high‐angle, planar joints. The columnar joints divide the rock mass between those planar joints. This may imply that the high‐angle joints would have formed probably during cooling under the presence of tectonic and thermal stresses.