scholarly journals Dormant landslides distributed in upper course of Sun Kosi Watershed and landslides induced by Nepal Gorkha Earthquake 2015

2018 ◽  
Vol 55 (1) ◽  
pp. 61-67 ◽  
Author(s):  
Hiroshi Yagi ◽  
Kazunari Hayashi ◽  
Daisuke Higaki ◽  
Ching-Ying Tsou ◽  
Go Sato
Keyword(s):  
Large Scale ◽  
Slope Angle ◽  
Area Ratio ◽  
Slope Gradient ◽  
Landslide Area ◽  
Gorkha Earthquake ◽  
Augen Gneiss ◽  
Steep Slopes ◽  
Lower Slope ◽  
Dip Slope

This study detected 897 dormant landslides of deep-seated type in the upper course of the Sun Kosi Watershed. It also shows geology and slope gradient that are prone to cause deep-seated landslides in the Great Himalaya and Midland zones. The dormant landslides are predominantly distributed in geological areas of the Augen Gneiss, Benighat Slate, Robang Phyllite and the Kuncha Phyllite, considering both landslide area ratio and site number. Landslides of deep-seated type are also found prone to develop on dip-slope. Occurrence of landslides usually increases over 20 degrees of slope angle for each geological type, though the number of landslides in the phyllite area increases below 20 degrees. It is very clear that landslides in phyllite area are prone to occur from relatively lower slope angles compared to those occurring in quartzite, gneiss and the Sermathang Formation. Nepal Gorkha Earthquake 2015 caused 1804 landslides in this study area. Most of the earthquake-induced landslides are of shallow types that occurred just below break of slope, showing a shoulder shaped profile along the deep gorge. They are predominantly distributed on steep slopes in the geological areas of slate, gneiss and dolomite. None of the dormant landslides of large scale was activated by the earthquake.

Influence of tillage displaced soil on the productivity and yield components of barley in northwest Iran

2012 ◽  
Vol 92 (4) ◽  
pp. 665-672 ◽  
Author(s):  
Leila Nazmi ◽  
Hossein Asadi ◽  
Ruzanna Manukyan ◽  
Hamdollah Naderi
Keyword(s):  
Field Experiment ◽  
Yield Components ◽  
Slope Position ◽  
Soil Productivity ◽  
Slope Gradient ◽  
Position Effects ◽  
Northwest Iran ◽  
Lower Slope ◽  
Tillage Erosion ◽  
Upper Slope

Nazmi, L., Asadi, H., Manukyan, R. and Naderi, H. 2012. Influence of tillage displaced soil on the productivity and yield components of barley in northwest Iran. Can. J. Soil Sci. 92: 665–672. In hilly landforms subject to long-term cultivation, erosion has denuded the upper slope positions of topsoil, and accumulated topsoil in the lower slope positions. Slope gradient and position effects aggregation processes, which in turn impact soil productivity. A field experiment was conducted to assess the tillage-induced soil displacement and its effects on the soil properties and barley (Hordeum vulgare var. Sahand) biomass production for three different landscapes. The study was conducted on a hill slope seeded with barley (1.4–10.1° slope) located in the Mollaahmad watershed of the Ardabil province in northwestern Iran. For this purpose, soil samples were collected from four slope positions in a grassland as well as an agricultural field (dryland). A field experiment was conducted to evaluate the effects of slope gradient and position on barley growth and soil quality. Soil generally had lower organic carbon, available phosphorus, calcium carbonate equivalent, soil water content and mean weight diameter of soil aggregates in the farmland than the grassland, and in the upper slope positions than in the lower slopes. Significantly higher barley growth indices were associated with lower slope positions. Agronomic productivity of the soil was lowest for landscapes with the highest slope gradient. The relationships between tillage erosion and yield components were found to be significant. Spike weight and slope position had the largest contribution for the explanatory capacity of canonical variables (tillage erosion and yield components) estimated when compared with other parameters (slope gradient, dry matter, spike number, grain yield and 1000-grain weight). The findings in this study can be used as a tool to assist farmers, soil and water conservationists, and other policymakers in decision making regarding the use of lands.

scholarly journals Seismic activity in the focus of the Uglegorsk earthquakes, Sakhalin Island in relevance to intensive development of coal deposits

2021 ◽  
Author(s):  
Dmitry Kostylev ◽  
Natalya Boginskaya ◽  
Alexander Zakupin
Keyword(s):  
Brown Coal ◽  
Coal Mine ◽  
Seismic Activity ◽  
Large Scale ◽  
Slope Angle ◽  
Sakhalin Island ◽  
Corner Frequency ◽  
Seismic Events ◽  
Velocity Spectrum ◽  
Human Engineering

Abstract Induced seismicity is an increase in seismic activity caused by the human engineering. An example of such activity is the mineral exploration, large water reservoirs construction, exploitation of underground oil and gas storages, etc. The authors studied the seismicity in the Uglegorsky district of Sakhalin region, where the Solntsevskoye brown coal field is located, which is the most promising in the island. Its area is over 100 sq. km, and productive strata of the Verkhneduiskaya formation with a thickness of up to 600 m contains 12 coal seams, 8 of which are working. Active mining of brown coal is carried out at the Solntsevsky coal mine, and blasting operations are performed on a large scale, that, as a result, does not exclude the relation of the seismic process to technogenic seismicity. The earthquake recurrence curves for two decades beginning from 2000 to the present were constructed in the work to compare the characteristics of the seismic regime in the studied area. The difference in the slope angle of recurrence graph during the period of 2011-2020 (the period of the most active development of the Solntsevsky coal mine) from the previous decade is quite significant. The maps of spatiotemporal distribution of seismic events epicenters in the vicinity of Solntsevsky coal mine are constructed. The contraction of zones of seismic events concentration to the mining areas, first of all to the Solntsevsky coal mine, have been found. Such a combination allows us to talk about an increase in seismicity of the region during the last years and change in its character from the natural to a mixed natural and technogenic. The focal mechanisms of the largest earthquakes occurred in the Uglegorsky district have been constructed in order to prove the change in seismicity character and reasons for the earthquake occurrence in the studied area. The mechanisms of seismic events of 2020 are classified as strike-slip faults, that is not character for the most earthquakes on the territory of Sakhalin Island. The authors made an attempt to determine the regularities of the parameters of the produced blasts and earthquakes through dynamic parameters of the seismic events foci by means of studying the frequency content of earthquakes and blasts in order to determine a corner frequency from the focal velocity spectrum.

IX. Report on the eruptions of the soufrière, St. Vincent, 1902, and on a visit to Montagne Pelèe, in Martinique. -Part I.

1903 ◽  
Vol 200 (321-330) ◽  
pp. 353-553 ◽  
Author(s):  
Tempest Anderson ◽  
John Smith Flett
Keyword(s):  
Tropical Forest ◽  
Sugar Cane ◽  
Large Scale ◽  
Main Axis ◽  
The Caribbean ◽  
Geological Work ◽  
Steep Slopes

The islands of the Caribbean chain have been occupied by European colonists for several hundred years, yet they cannot even at the present day be said to be thoroughly known or sufficiently explored. Though small, they are for the most part moun­tainous, and present usually a ridge or backbone of high land forming the main axis of each island, with sharp spurs on each side running down to the sea. Cul­tivation is practically confined to the lower grounds, where alone there are goodroads, and the interior is covered with dense tropical forest, the aspect of which varies greatly with the altitude, and through which there are only rough bush paths. The valleys are usually very deep and narrow, and the steep slopes are covered with plantations of arrowroot, limes, cocoa, coffee, banana or plantain, while most of the level alluvial ground in the valley bottoms is given up to the growth of sugar cane. In all the British islands, at any rate, the principal peaks and ridges have been ascended, and the main features of the country are delineated on the Admiralty charts, which are the best, and in fact the only available maps. As regards the coast-lines and the lower grounds generally, they are very accurate; but in theinterior only the more important points, the principal mountain summits and the like, have had their position sufficiently determined. The rest of the country has apparently been sketched in more or less carefully—but many of the details as, for example, the courses of the smaller streams, and the number of their branches, cannot be relied on. The want of a good map on a fairly large scale is a great drawback in geological work, and prevents the structure of the country being laid down with anyapproach to minuteness.

scholarly journals Numerical Simulation of Katabatic Flow with Changing Slope Angle

2005 ◽  
Vol 133 (11) ◽  
pp. 3065-3080 ◽  
Author(s):  
Craig M. Smith ◽  
Eric D. Skyllingstad
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
Slope Angle ◽  
Gravitational Potential Energy ◽  
Flow Profile ◽  
Advanced Regional Prediction System ◽  
Regional Prediction ◽  
Les Model ◽  
Lower Slope ◽  
Upper Slope

Abstract A large eddy simulation (LES) model and the Advanced Regional Prediction System (ARPS) model, which does not resolve turbulent eddies, are used to study the effect of a slope angle decrease on the structure of katabatic slope flows. For a simple, uniform angle slope, simulations from both models produce turbulence kinetic energy and momentum budgets that are in good overall agreement. Simulations of a compound angle slope are compared to a uniform angle slope to demonstrate how a changing slope angle can strongly affect the strength of katabatic flows. Both ARPS and the LES model show that slopes with a steep upper slope followed by a shallower lower slope (concave shape) generate a rapid acceleration on the upper slope followed by a transition to a slower evolving structure characterized by an elevated jet over the lower slope. In contrast, the case with uniform slope (having the same total height change) yields a more uniform flow profile with stronger winds at the slope bottom. Higher average slope in the uniform slope angle case generates greater gravitational potential energy, which is converted to kinetic energy at the bottom of the slope. Analysis of the total energy budget of slope flows indicates a consistent structure where potential energy generated at the top of the slope is transported downslope and converted into kinetic energy near the slope base.

Diapycnal Transport and Mixing Efficiency in Stratified Boundary Layers near Sloping Topography

2011 ◽  
Vol 41 (2) ◽  
pp. 329-345 ◽  
Author(s):  
Lars Umlauf ◽  
Hans Burchard
Keyword(s):  
Boundary Layer ◽  
Boundary Layers ◽  
Slope Angle ◽  
Low Frequency ◽  
Moment Closure ◽  
Mixing Efficiency ◽  
Small Scale ◽  
Second Moment Closure ◽  
Steep Slopes ◽  
Sloping Topography

Abstract The interaction of shear, stratification, and turbulence in boundary layers on sloping topography is investigated with the help of an idealized theoretical model, assuming uniform bottom slope and homogeneity in the upslope direction. It is shown theoretically that the irreversible vertical buoyancy flux generated in the boundary layer is directly proportional to the molecular destruction rate of small-scale buoyancy variance, which can be inferred, for example, from microstructure observations. Dimensional analysis of the equations shows that, for harmonic boundary layer forcing and no rotation, the problem is governed by three nondimensional parameters (slope angle, roughness number, and ratio of forcing and buoyancy frequencies). Solution of the equations with a second-moment closure model for the turbulent fluxes reveals the periodic generation of gravitationally unstable boundary layers during upslope flow, consistent with available observations. Investigation of the nondimensional parameter space with the help of this model illustrates a systematic increase of the bulk mixing efficiencies for (i) steep slopes and (ii) low-frequency forcing. Except for very steep slopes, mixing efficiencies are substantially smaller than the classical value of Γ = 0.2.

scholarly journals CHARACTERISTICS OF FLOW IN RUN-UP OF PERIODIC WAVES

1976 ◽  
Vol 1 (15) ◽  
pp. 44 ◽  
Author(s):  
Ary Roos ◽  
Jurjen A. Battjes
Keyword(s):  
Slope Angle ◽  
Water Layer ◽  
Periodic Waves ◽  
Wave Steepness ◽  
Slope Gradient ◽  
Characteristic Parameters ◽  
Similarity Parameter ◽  
The Mean ◽  
Run Up ◽  
Particle Velocities

An experimental study is presented of some characteristic parameters of the flow in the up-rush and down-rush of periodic waves breaking on a plane, smooth slope. The water layer thickness has been measured as a function of time at four locations above still water level. Discharges and particle velocities have been calculated. The results have been made nondimensional on the basis of Hunt's formula for the run-up height. They appear to be either independent of the wave steepness H/L and slope gradient tan Ct or to be a function of a single similarity parameter £ - tana / yH/L only. An hypothesis is stated concerning a relation between the mean rate of overtopping of a dike by waves, and the run-up which would occur under the same circumstances on an uninterrupted slope. On the basis of this hypothesis the overtopping volume per wave can be normalized so as to make it independent of slope angle and wave steepness. A comparison of the result with measurements from other sources indicates a rough agreement.

scholarly journals Estimasi Cadangan Karbon Pada Tumbuhan Bawah dan Serasah Di Hutan Pendidikan dan Penelitian Fakultas Kehutanan Universitas Mulawarman Samarinda

2021 ◽  
Vol 5 (2) ◽  
pp. 55
Author(s):  
Wahjuni Hartati ◽  
Ali Suhardiman ◽  
Triyono Sudarmadji ◽  
Syahrinudin Syahrinudin ◽  
Eko Adi Sulistiyo
Keyword(s):  
Leaf Litter ◽  
Woody Plants ◽  
Secondary Forest ◽  
Forest Coverage ◽  
Steep Slopes ◽  
Lower Slope ◽  
Made In

Three slopes of 100 m long are defined in young secondary forest with gentle and slightly steep slopes. In each part of the slope, we built 1 (one) PUP of 20m x 20m which is consisted of 3 (three) Sub PUPs of 10m x 10m to represent the density of sparse, medium and dense understorey and 1m x 1m of sub-PUPs for litter harvesting. A total of 18 (eighteen) PUPs, each 54 (fifty four) Sub PUPs and Sub sub PUPs were made in this study. The HPFU area is dominated by young secondary forest coverage with gentle and slightly steep slopes. The C reserves of herbaceous understorey is greater than that of woody plants. C reserves of all components studied in the gently sloping area are greater than the steep ones. The largest C reserves is found in leaf litter for all slope positions except for a slightly steep lower slope, the largest C reserves is found in finer litter. The total C reserves of understorey and young secondary forest organic litter in HPFU 933.4 tonnes and 95.9% are stored in litter.

scholarly journals Effect of the Slope Angle and Its Classification on Landslide

2020 ◽  
Author(s):  
Seda Çellek
Keyword(s):  
Landslide Susceptibility ◽  
Slope Angle ◽  
Landslide Area ◽  
Advantages And Disadvantages ◽  
Definition Of ◽  
Landslide Maps ◽  
Selection Of

Abstract. The phase after the determination of the landslide area in landslide susceptibility studies is the selection of methods and parameters to be used. Approximately 1500 randomly selected publications show that it is necessary to select a parameter based on the area. Research has shown that the parameter of slope is greatly preferred. There is nearly consensus of opinion among researchers regarding the use of the parameter. The research included the definition of slope made by different researchers, the advantages and disadvantages of the use of the parameter, different classifications that are used, the formation intervals of landslides, their use together with other parameters, and its effect on the formation of landslides. Classifications were studied based on the slope values at which landslides. Generally, automatic slope classifications are used in the preparation of landslide maps. There isn’t standard in parameter maps. Therefore, there isn’t class range that is referenced when preparing slope maps. In this study, preferred class ranges and slope values where landslides occur were determined in the literature. 40 landslides area has been selected in Turkey. These were evaluated in the slope classes determined according to the literature. The results compared with the literature were found to be compatible.

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