High Mountain Slopes Research Articles

Study of large-scale deformation induced by gravity on the La Clapière landslide (Saint-Etienne de Tinée, France) using numerical and geophysical approaches

Abstract The large-scale deformation of high mountain slopes finds its origin in many phenomena with very different time-constants. Gravitational effect, tectonic forces, and water infiltration are generally the principal causes. However, it is always very difficult to distinguish which cause is dominant and which are their respective effects. A two-dimensional numerical experiment coupled with geophysical approach was carried out to determine (1) the effect of gravitational force on the mechanical behaviour of the “la Clapiere” area, (2) a 2D-depth structure of this landslide. The results show that gravitational instability is possible and leads to destabilisation of the massif by a regressive evolution of the landslide from the bottom at 1100 m up to a height of 1800 m, which is actually the top of the La Clapiere landslide. This deformation progression only concerns a depth of around 150 ± 50 m, which can be correlated to the sliding surface, as suggested by our electrical data obtained by resistivity investigations and previous studies. Our numerical results suggest that changes of the slope topography “drive” the diffusion of the plastic deformation in the mass, possibly through a channel which could be then the privileged zone along which the fracture is initiated.

A Review of Japanese Debris Flow Research

The phenomenon of debris flow has been recognized since ancient times in Japan, where debris flow disasters have caused damage and suffering. In steep mountainous areas of Japan, residents have given evocative names to debris flows to warn future generations of their danger. Such names include “Ja-nuke” (the runoff of the king snake), “yama-tsunami” (mountain tsunami), and “yama-shio” (mountain tide). However, because debris flows usually originate on remote high mountain slopes or steep ephemeral gullies and arise during adverse weather conditions, the characteristics and mechanisms of debris flows had long remained poorly understood and the phenomenon was even considered a “phantasmal disaster.” Scientific investigations of debris flow began in the 1950s and included qualitative discussions of the definition of debris flow. Nomitsu and Seno [1959], Tani [1968], and Murano [1968] defined debris flow as the gravitational motion of a porridge-like mixture of sediment and water, in which the volume of sediment is much larger than the volume of water. Koide [1955] classified debris flow into “yama-tsunami” and “doseki-ryu” types. He defined a yama-tsunami as the pushing ahead of a cohesive earth mass produced by a landslide along a valley and a doseki-ryu as the pushing ahead of sediment accumulated on a gully bed. Thus, a doseki-ryu had no direct relationship to a landslide. Kaki [1954] defined a yama-tsunami as a forward-moving mixture composed of 70% soil and 30% water and a doseki-ryu as a flow composed of 30% soil and 70% water with relatively thin depth. The term doseki-ryu is now widely used in Japanese to refer to debris flow; “doseki” means a mixture of soil and stone, and “ryu” means flow. Tani [1968] classified three types of debris flow initiation: 1) transformation of a landslide block into debris flow, 2) collapse of a landslide dam, and 3) sediment entrainment into the surface water flow on a gully bed. He also compiled several observed characteristics of debris flow: 1) The lateral surface profile of flow is upward convex, with the front part swelling longitudinally. 2) The flow is dominated by soil and stone rather than water and resembles a moving hill composed of stone, sand, mud, and wood that produces a smoke-like cloud of debris and a bad smell. 3) The sound is like that of thunder or a formation of airplanes. Yano and Daido [1965] referred to debris flow as “mud flow.” They defined it as a flow of muddy clay and modeled its motion by applying concepts of pseudoplastic fluid and Bingham fluid. Full investigations were not undertaken until the 1970s. By that time, improvements of major rivers had lessened the risk of large-scale flooding disasters. However, management of minor rivers lagged behind that of major rivers, and the use of slope lands for human activities increased vulnerability to sediment hazards. Before 1964, among human victims of total water-related hazards, 32% were affected by sediment events. Since 1965, this percentage has increased to approximately 50% [Takahashi, 2009]. This situation provides strong motivation for research on debris flow and other sediment hazards.

Homeland Beauty: Transnational Longing and Hmong American Vidoe

SINCE 1975, AFTER THE WITHDRAWAL OF THE UNITED STATES from intervention in the Vietnam War, Hmong highlanders from Laos have been arriving in the West. Those Hmong who became refugees had assisted the CIA in a covert anticommunist effort within Laos; the failure of this effort necessitated political exile, especially for those who had served as guerrillas. Minorities in their homelands, they had dwelled on the high mountain slopes, practicing swidden agriculture, speaking Hmong language, and retaining distinctive styles of dress and a highly elaborated religiocultural system.' Through their alliance with the United States, they had hoped in vain to gain a greater measure of political self-determination within Laos.2 Instead, perhaps two hundred thousand Hmong now reside in various localities across the United States. Smaller communities are found in France, Australia, Canada, and French Guyana. It was with haste and regret that they left their homes, and, even after more than two decades have passed, for many of the middle and elder generations, their longing for the Asian agrarian lifestyles that they have lost has remained alive. For some Hmong, whose residence in the United States has eventuated in citizenship and/or a degree of economic security, this longing has taken the form of nostalgia touring-to Laos, Thailand, China, even Vietnam-in search of a sense of connectedness to the lives from which they were so abruptly severed.3 Hmong still live agrarian lives in villages in all of these countries. A huge settlement was also formed in Thailand, comprising over twenty thousand Hmong refugees from Laosclosely tied as family and friends to Hmong Americans-who had been displaced with the closing of the last officially sponsored refugee camp and who found alternate

Soil moisture variability in relation to diurnal frost heaving on Japanese high mountain slopes

Frost heave, ground temperature and moisture were concurrently monitored on two alpine slopes with thin debris mantles. Electrical sensors connected to data loggers permitted automated monitoring of the three variables. Diurnal frost heave of up to 3 cm frequently took place during spring and autumn. Soil moisture contents are regarded as the primary control on the amount of frost heave, while the intensity of freezing is secondary. Heave was usually greatest just after a major rainstorm that produced high moisture contents in the near-surface soil, and decreased with soil desiccation. Rainstorms often interrupted the desiccation process and reactivated frost heaving. Despite reaching a depth of 1 m or more, seasonal frost penetration caused only small amounts to heave, because the lower part of the seasonally frozen layer was not frost-susceptible. These observations imply that the thin debris mantle and periodic precipitation during periods of freeze-thaw combine to result in the predominance of shallow frost creep, which is typical of soil movements in Japanese high mountains.

Soil moisture variability in relation to diurnal frost heaving on Japanese high mountain slopes

Soil moisture variability in relation to diurnal frost heaving on Japanese high mountain slopes

Differences in Big Sagebrush (Artemisia tridentata) Plant Stature along Soil-Water Gradients: Genetic Components

Genotypic and phenotypic variations are characteristic among big sagebrush (Artemisia tridentata) plants. One obvious expression is the variability of big sagebrush plant stature along soilwater gradients. Large plants are usually associated with mesic habitats such as drainages or swales, while small plants occupy the xeric portions of the gradients. The purpose of this study was to investigate the genetic influence on big sagebrush plant stature along soil-water gradients. Leaf morphological, phenological, chromatographical, and cytological investigations evaluated potential genetic differences and examined possible subspecies status of the large and small plants. The results of these studies revealed a genetic difference between the large and small plants and confirmed subspecies status. The large plants were identified as basin big sagebrush (A. tridentata spp. tridentata) while the small plants were Wyoming big sagebrush (A. tridentata spp. wyomingensis). Three additional studies examined possible differences in growth potential between the subspecies. A greenhouse and uniform garden study compared seedling and juvenile plant growth. Annual leader growth of mature plants was measured in native populations. Basin big sagebrush plants outgrew Wyoming big sagebrush in the greenhouse, uniform garden, and leader growth experiments. Difference in growth potential between the subspecies may be a consequence of ploidy differences. The most common, important, and widely distributed woody sagebrush (Artemisia L. subgenus tridentatae (Rydb.) E.D. McArthur) is big sagebrush (Artemisia tridentata Nutt.). Big sagebrush is common on millions of hectares throughout western North America from southern Canada to northern Mexico (Beetle 1960, McArthur et al. 1981). This shrub has a wide range of adaptability and grows in various soil types and is associated with numerous plant species from low elevation valleys and plains to high mountain slopes and ridges (Morris et al. 1976, Winward and Tisdalel977, Winward, 1980). Big sagebrush provides browse and habitat for an array of wildlife and livestock, minimizes soil erosion, and is of value in mined-land reclamation. Big sagebrush, as do other plant species, adapts to diverse environments through a combination of phenotypic plasticity and genotypic variation. As Caldwell (1979) theorized, the phenotypic diversity of plants is remarkable, but it is not sufficient to accommodate extensive environmental conditions that are found in the range of a widely distributed species such as big sagebrush. Presently, the big sagebrush complex consists of 4 subspecies (Beetle 1960, Beetle and Young 1965, Goodrich et al. in press, McArthur 1983) which are: basin big sagebrush (A. tridentata Nutt. ssp. tridentata), Wyoming big sagebrush (A. tridentata Nutt. ssp. wyomingensis Beetle and Young), mountain big sagebrush (A. tridentata Nutt. ssp. vaseyana (Rydb.) Beetle), and subalpine sagebrush (A. tridentata Nutt. ssp speciformis (Osterhout) Goodrich and McArthur). Authors are former graduate research assistant and professor, respectively, Department of Range Science, Utah State University, Logan. Authors are presently, lecturer, Department of Botany and Range Management, Somali National University, Mogadishu, Somalia and Vice-President for Research, NPI, 417 Wakara Way, Salt Lake City, Utah 84108. Research was supported by the U.S. Department of Energy and Ecology Center and Department of Range Science, Utah State University. We thank E.D. McArthur for technical assistance, use of laboratory equipment, and review of a draft manuscript. Manuscript accepted 3 July 1985. Genotypic and phenotypic variation is characteristic of big sagebrush (Beetle 1960, Hanks et al. 1973, McArthur et al. 1981, West et al. 1978). An obvious expression is the variability in big sagebrush plant stature along soil-water gradients (Beetle 1960, Hall and Clements 1923, Hanks et al. 1973). Large plants may reach a height of 3.5 to 5.0 m in mesic habitats such as drainages or swales, while plants less than 1.0 m tall are associated with the xeric portions of moisture gradients. Considering the differences in big sagebrush plant stature, a logical question arises: Are the differences in plant stature due to genetic or environmental influences? The research herein discusses the influence of genetics on big sagebrush plant stature. Edaphic differences associated with the large and small big sagebrush plants are reported elsewhere (Barker 1981, Barker and McKell 1983).

Geological and geotechnical engineering aspects of low-cost roads in mountainous terrain

The paper is concerned with design and construction of mountain roads in areas of high relief and steep mountain slopes, where the principal soil types are transported rather than residual and the landscape is shaped mainly by active erosion processes. In order to simplify the wide range of ground conditions encountered, the geology and geomorphology of typical mountain terrain are described and related to a five zone model. Geotechnical features within each zone are then considered so that the application of various investigation and construction techniques can be appreciated. The paper is primarily concerned with low-cost but well-trafficked primary roads where closure time due to slope failures or lack of maintenance are intended to be minimal. Village feeder roads and steep mountain haul roads, for example those used in forestry, are not the prime concern of the paper. Three aspects which distinguish mountain roads from typical lowland roads are the difficult ground access with numerous slope instability problems, the greater use of very local construction materials and the greater need for off-site drainage and erosion protection measures. In remote rugged terrain access for wheeled traffic may not exist. This severely curtails the use of conventional site investigation techniques, such as drilling, and means that greater emphasis is placed on remote sensing and on the surface assessment of ground conditions. Several relatively new low-cost techniques applicable to the investigation of mountain regions are described. A rational approach to alignment selection is developed which stresses the importance of stable ascent corridors, and practical guidelines are offered on the selection of the road cross-section and on the variety of techniques available to stabilise the cross-section chosen. The use of local construction materials is dictated largely on economic grounds and may place heavy constraints on construction standards and structural design. The use of gabion structures is a major construction technique examined in the paper. Drainage and erosion protection methods are important in areas of high relief and erosion potential and a range of design approaches are described. The bulk of stabilisation and control works described can only be attempted by labour

Double Ridges on Mahabharat Lekh (Range), Lower Himalaya Zone, South Nepal

Double ridges composed of uphill-facing scarp and linear depression are one of the most remarkable topography on high mountain slope. In this paper double ridges are examined on the ridge-top of Mahabharat Lekh (Range) north of Dang Dun (Basin), Lower Himalaya Zone, South Nepal.Low relief surface develops on the ridge around the study site. The lower slope is very steep. The cross section of the ridge shows a dome like skyline because of overburdened mountain top with it's own load. Mahabharat Lekh (Range) is composed of Quartzite, Quartzose sandstone and Phyllite. They had experienced slight metamorphism. Their strikes are parallel to the ridge and the dip angles range between 25°N and 60°N.Uphill-facing scarps 5-15m high and linear depressions develop parallel to the ridge at the altitude of 1, 700-1, 900m a. s. l.. An exposure across the double ridges (G-H cross section) shows that highly fractured zone is formed along the underground extension of the line between the ridge-top and the bottom of the linear depression, and that slickenside is formed on the surface of unfractured bedrock beneath the highly factured zone. The boundary between them is parallel to the bedding plane of the bedrock.Considering from the above mentioned features on the double ridges developing on the main ridge of Mahabharat Lekh (Range), their origins are due to the gravitational slide of the ridge-top and the mountain slope to the north along the bedding plane of the bedrock.

THE ORIGIN OF UPHILL-FACING SCARPLETS DISTRIBUTED ON THE HIGH MOUNTAIN SLOPES OF JAPAN

Uphill-facing scarplets are often distributed on the high mountain slopes of Japan. They have been called “double ridges”, or “linear depression”, the origin of which has been disputed among geomorphologists. In this paper the author investigated their topographical characteristics such as mode of occuerrence, height, distribution and cross sections of rides on which they appear. He also refers to their origin applying a two-dimensional finite-element calculation of the self gravitational stress to a model mountain, on the slopes of which the scarplets are often distributed. The results can be summarized as follows. 1. The scarplets are mostly recognized in high mountain areas with high relief caused by the rapid uplift during the Quarternary (Fig. 2). 2. Most of them appear on the mountain slopes higher than 2, 000m a. s. l., but some are recognized on the slopes lower than 1, 000m a. s. l. in case of the slopes with high relief (figs. 3, 5 and 6). 3. They are mainly formed on ridges deeply dissected by V-shaped valleys (e. g. the Kurobe) (Fig. 7), cross sections of which consist of two parts; very steep lower slopes formd by deepening and gentle upper slopes or flat surfaces around ridges. Therefore, the sections generally show convex outlines as a whole (Figs. 8 and 9). Scarplets are usually located just above breaks between steep and gentle slopes. 4. Brittle fractures caused by the self load of mountain will be expected to occur around ridges of mountain (Figs. 11 and 12) by the analysis applying the finite-element method. Therefore, uphill-facing scarplets may be originated from the subsidence of ridges caused by local faulting.

Deep—Reaching gravitational deformations of high mountain slopes

Some of the high mountain slopes are affected by deep-reaching gravitational deformations. Significant geomorphological manifestations of these deformations were described from many high mountain ranges of the world. The type of deformation depends on the geological structure of the slope. During the last ten years various opinions on the movement mechanism of these slope deformations have been expressed and schematic cross-sections drawn. Dips of slope deformations are given within the range of 18o to 50o. A whole series of factors may be responsible for the origin of these deformations. Deep-reaching gravitational deformations can cause serious economic damage.

Disjunctions in Bryophytes

Disjunctions in Bryophytes

Impact of Technology on Traditional Agriculture: The Peru Case

BOTH geographically and economically, Peru is divided into three major regions-the Coast, the Sierra, and the Selva. The Coastal region contains the major urban-industrial centers and a productive agricultural sector based largely on cotton and sugarcane production in the fertile irrigated valleys. The vast tropical Selva region comprises 60 percent of Peru's area but is sparsely populated, largely unexplored, and essentially isolated from the Coastal region by the Sierra. The Sierra region is a densely populated, low-income agricultural region based upon subsistence cereal and tuber production at the lower altitudes and livestock production on the high plains and mountain slopes. Although 52 percent of Peru's total population and 70 percent of the active agricultural labor force is located in the Sierra region, the Sierra region produces only 19 and 41 percent of the gross value of total production and gross value of agricultural production, respectively. Gross National Product per active worker in Sierra agriculture is approximately $109, as compared with $960 for non-Sierra agriculture, and $1,461 for nonagriculture [2, pp. 3-6]. The problems of the Sierra region are further complicated by short-day lengths, frost and drought hazards, rough and mountainous terrain, poor nonagricultural employment opportunities, bare subsistence diet levels of about 1,100 calories per day per capita, a primitive transportation network, a 67-percent rate of illiteracy, and stable or declining crop yields.' Given this brief but harsh description, it is clear that a program to reorient and redirect the Sierra economy is needed. The objective of this study is to examine one possible component of such a program-the effects of the

Substitution of small cans for weather bureau pans in measuring evaporation

Information about free-water surface evaporation on high mountain slopes is scarce because it is difficult to obtain a handy supply of water and to service research installations regularly in such remote locations. A recent study on areas at about 8200 feet elevation in the head of Parrish Canyon (Fig. 1) near Farmington, Utah, showed that small cans could be used to substitute for and to reduce the amount of ‘standard’ equipment needed. The small cans were much easier to service because only small amounts of replacement water were required. Plan of study. Evaporation was measured during the summers of 1957 and 1958 in Class A, 4-foot-diameter by 10-inch-deep, land surface pans and in 6.5-inch-diameter by 8.75-inch-deep cans [Weather Bureau, 1955]. The cans were shaded with horizontal sunshields of unpainted masonite because preliminary measurements indicated that water temperatures and evaporation were higher in the cans than in the pans.

Mammals from Kurdistan, Iraq, with Description of a New Bat

During 1954 a small collection of mammals was made by the author in the extreme north of Iraq, which forms part of Kurdistan. This is an extremely mountainous district and the mountain ranges are continuous with those of Asia Minor and Persia. The mammalian fauna is composed of animals which are quite different to those found in the lowlands and desert of which most of Iraq consists and includes many species which are found in Persia, Asia Minor and Syria. It appears to be a faunal element which has been but little studied in Iraq for a number of the species recorded here have not been previously noted as existing in that country. The collection here described was made in the mountains around Amadia, Kurdistan. In this area the mountains are quite extensively covered with scrub oak forest, while the valleys are very fertile and contain poplars and other trees (See Plate I). Plate I 1. Country near Hais, Kurdistan. Photograph by the author. 2. Habitat of Meriones persicus . Burrow beneath rock on a high mountain slope at Ser'Amadia. Photograph by the author. 3. Habitat of the grey hamster ( Cricetulus migratorius ) on a mountain slope at Ser'Amadia. Photograph by the author. 4. Earth mounds made by Spalax ehrenbergi on high mountain slopes near Ser'Amadia. Photograph by the author. The mammals obtained are listed below, with notes on their characteristics and field habits and with a description of a new bat. Meriones persicus Blanford. Persian sand rat.—This large and interesting gerbil is known from Persia, Afghanistan, Baluchistan, Asiatic Turkey, Transcaucasia and Russian Turkestan. It is not known hitherto from Iraq. An adult female specimen was collected at Ser'Amadia, Kurdistan on August 12, 1954, at an altitude of about 6000 feet. The species is readily distinguished by its large size (hind foot …