Range Of Slope Angles Research Articles

Orientation of the Cochlea From a Surgeon's Perspective.

One of the mechanisms that cause tip fold-over is a misalignment between the electrode array's coiling direction and the cochlea's curving direction. We reviewed surgical videos and computed tomography (CT) datasets of the patients who underwent cochlear implantation procedures from January 2010 to December 2021, paying particular attention to the cochlea's orientation in the surgeon's microscopic view. CT dataset and video recordings were analyzed to measure the "slope angle," which is the angle between the cochlea's coiling plane and the horizontal plane. There were 220 cases that met the criteria and completed the analysis. The mean slope angle was 12.1° ± 9.5°, with a minimum of -9.4° and maximum of 44.6°. However, each surgeon had a favored slope angle range. Understanding the slope angle and making an effort to reduce the chance of misalignment during electrode insertion may help prevent tip fold-over of slim perimodiolar electrode arrays.

Development and distribution of ancient landslides in the northwest corner of the Tibetan Plateau

The periphery of the Tibetan Plateau is a landslide-prone area, yet there is a lack of satisfactory results on the development and distribution of landslides due to low human activity and inconvenient transportation within this area. In this study, taking 38–40°N and 73–76°E as the study region, a detailed distribution map of ancient landslides, including 5378 landslides with a total area of 2705.02 km2, is established with the help of Google Earth Engine platform using manual visual interpretation. The numbers and areas of landslides, classified in terms of elevation, slope angle, slope aspect, fault distance, and water system distance, are analyzed. The development of landslides is closely correlated with topographical and geological factors. After comprehensive analysis, we conclude that both the number and total area of landslides in the elevation range of 4–5 km are the greatest; more landslides happen in the slope angle range of 40°–50°; the total area of landslides in the slope angle range of 50°–60° is the largest; both the number and total area of landslides with slope aspects of N, NE, and NW are the greatest; the ancient landslides in this region were weakly impacted by tectonic movement and seismic activity, and more likely caused by reasons like climate change; and the occurrence of ancient landslides in this region is insignificantly correlated with water systems.

A temperature-dependent mechanical model to assess the stability of degrading permafrost rock slopes

Abstract. Over the last 2 decades, permafrost degradation has been observed to be a major driver of enhanced rock slope instability and associated hazards in high mountains. While the thermal regime of permafrost degradation in high mountains has been addressed in several modelling approaches, no mechanical models that thoroughly explain rock slope destabilisation controls in degrading permafrost have been developed. Meanwhile, recent laboratory studies have shown that degrading permafrost affects both, rock and ice mechanical strength parameters as well as the strength of rock–ice interfaces. This study presents a first general approach for a temperature-dependent numerical stability model that simulates the mechanical response of a warming and thawing permafrost rock slope. The proposed procedure is exemplified using a rockslide at the permafrost-affected Zugspitze summit crest. Laboratory tests on frozen and unfrozen rock joint and intact rock properties provide material parameters for discontinuum models developed with the Universal Distinct Element Code (UDEC). Geophysical and geotechnical field surveys reveal information on permafrost distribution and the fracture network. This model can demonstrate how warming decreases rock slope stability to a critical level and why thawing initiates failure. A generalised sensitivity analysis of the model with a simplified geometry and warming trajectory below 0 ∘C shows that progressive warming close to the melting point initiates instability above a critical slope angle of 50–62∘, depending on the orientation of the fracture network. The increase in displacements intensifies for warming steps closer to 0 ∘C. The simplified and generalised model can be applied to permafrost rock slopes (i) which warm above −4 ∘C, (ii) with ice-filled joints, (iii) with fractured limestone or probably most of the rock types relevant for permafrost rock slope failure, and (iv) with a wide range of slope angles (30–70∘) and orientations of the fracture network (consisting of three joint sets). Here, we present a benchmark model capable of assessing the future destabilisation of degrading permafrost rock slopes.

Impacts of terrain on convective surface layer turbulence over central Himalaya based on Monin–Obukhov similarity theory

In the context of non-uniform Monin–Obukhov similarity scaling of unstable surface layer turbulence over complex terrain, this study attempts to identify the range of slope angles (as a proxy for terrain complexity) over which convective turbulence behaviour is similar to that over flat terrain. Attempts are also made to optimize constants of numerical relationships between integral turbulence parameters (ϕu,v,w) and the stability parameter (z/L) for observations having a significantly strong signature of terrain undulation. High frequency wind observations during the Indian winter season obtained from two field stations (on-slope and ridge-top) in the central Himalaya near Kosi-Katarmal, Uttarakhand, India, are analysed. Convective day-time period observations from rain-free days at these two sites are used with measures of terrain heterogeneity, represented by the vertical wind-derived slope angle (θw), vertical wind-derived slope angle normalized with respect to maximum θw (θwˆ), and the terrain-derived slope angle (θt). When the relationship of wind-derived slope angle and terrain derived slope angle was assessed, we found that wind-derived slope angle(θw) sufficiently represents the terrain undulation with a correlation coefficient of 0.86 at a p-value < 0.001. Optimization was undertaken of the numerical relationships between the integral turbulence parameters (ϕu,v,w) and z/L for observations having a significantly strong signature of terrain undulation characterized by |θˆw|> 0.2. Results indicated that for selected runs with increasing terrain complexity, c1 decreases and d1 increases in ϕu,v,w=c1(1−d1zL)1/3 having ranges of c1 and d1 between 0.85–2.39, and 0.98–13.85, respectively.

Seismic shaking-enhanced impact effect of granular flow challenges the barrier design strategy

Barrier design considering the coupling effect of flow impact and seismic shaking is challenged and has not been covered in previous researches, thus we performed numerical simulations to obtain fundamental insights on this matter. The influence and mechanism of the effects of shaking direction and magnitude on the impact processes of dry granular flow are investigated using a range of slope angles. Slope-normal shaking exhibits the most significant influence on flow mobility. Under 0.99 g, the maximum velocity is enhanced by 10.23% and the accumulative kinetic energy increases by 8.12%, which is caused by the coupled effect of reduced frictional resistance and energy supplement, where the latter dominates. Slope-longitudinal shaking exerts a more significant effect on the impact force, showing that the overall peak force increases by 42.14% under 0.99 g shaking, which implies that the enhanced mobility is not the main cause of enhanced impact effect but the evolution of dead zone, whose stability is altered by seismic shaking bringing and leads the barrier design load to largely exceed the value required by traditional design strategies. The influence of shaking on granular flow impact dynamics is substantially more significant when the flow conditions are gentle: the normalized force discrepancy is reduced from 77.05% to 41.36% when the slope angle is increased from 25° to 40° under 0.99 g slope-longitudinal shaking. In addition, the limitations of current models and direction for future work are discussed, including the effect of the fluid phase in debris flow, real seismic ground motion, and barrier types.

Analysis and Prediction of Landslide using Drone Image and GIS Techniques- Case Study Aranayaka Area

Occurrence of Landslides has become a major impact considering the damage a landslide can do in a quick time. Among the natural hazards the country is exposed up to now, severe landslides are the upcoming major issue since it can affect to the lives of people too. In this case study from Aranayaka area, a method is developed to analyses and identify landslide prone areas. The methodology of the research includes collecting terrain data, building a model using geographic information system (GIS), satellite image processing, preparation of a landslide susceptibility potential map and giving recommendations on the landslide hazards. Among the factors that influence a landslide such as drainage, bedrock condition, slope angle range, land forms and etc. (published by National Building Research Organization), the foremost controllable and mostly varying factor. In this research, landslide prone areas are identified using the land use data. Identification of landslide hazards plays an important role in disaster management and risk controlling since a severe landslide can affect several aspects such as human lives, agricultural aspects, economic activities and transportation. This paper includes the background of the entire research that has developed up to current situation. This method can be used around the world as well as in the country.

Landslide impacts and management in Nanka area, Southeast Nigeria

The devastating impacts and mitigation measures for landslides in Nanka, Southeast Nigeria were studied. A procedure encompassing field mapping, laboratory analysis and limit equilibrium simulations were employed in the study. A total of 120 landslides in this area were documented during the field study. They were mainly shallow landslides with depth range of 0.2 m – 1.8 m and slope angle range of 36o - 65o. This study revealed that landslides in this area occur mainly during the rainy season, and are triggered by water infiltration in slopes with high gradient, where poorly consolidated sands overlies less permeable silty clay units in the Nanka Formation. The increase in pore water pressure due to soil saturation leads to reduction of the shear strength and loss of apparent cohesion. Geotechnical laboratory analysis showed that the thin silty clay soils found in the area have very high plasticity, while the sands are non-plastic. The limit equilibrium simulations revealed that as the slope angle increases, the potential slip mass volume increases. Our study in Nanka revealed that landslides have negatively affected the topography/morphology, settlement areas, agricultural lands and vegetation/land cover of the area and many areas are also threatened by this phenomenon. Standard mechanical drainage system and biotechnical slope protection have been suggested as mitigation measures. Finally, we suggested that landslide hazard information should be incorporated into long-term plans for Nanka and other areas prone to landslides, the public should be aware of the hazards and preventive measures.

Analytical design of an underwater construction robot on the slope with an up-cutting mode operation of a cutter bar

In this paper, the movements of the analytical models of complete underwater tracked vehicle (UTV) and cutter bar (CB) tool systems on a surface as well as their movements up and down a slope in the up-cutting mode operation are fully studied and analyzed. First, the mathematical expression of the mechanics, for which the forces, moments, and energy from the CB to the UTV are analyzed, is related. Next, analyses on the systemic parameters and their sensitivity are conducted to observe the variations of the operational and geometric parameters, as well as the cutter-tool and material-condition effects on the force, moment, and power components. Also, a design process composed of seven typical steps is proposed as the reference of a trencher-machine design. The important design parameters of the trenching machine such as the length of the CB, the nose radius of the CB, and the height of the pivot point are designed according to the proposed design process; furthermore, these parameters are used for the estimation of the slope-angle range when the trencher system is working on the slope. To demonstrate the application of derived equations to practical problems of the machine design, a number of numerical simulations are performed. Through the numerical simulations, the important parameters of the system such as the tangential force, Ft, the tractive thrust, H, the normal reaction, V, the cutting moment, Mc, the maximum carrier weight, W, and the available power are analyzed. From these, as a reference data for the designing of a trencher machine, the previous design of the system can be improved.

Critical runoff depth estimation for incipient motion of non-cohesive sediment on loose soil slope under heavy rainfall

Incipient motion of non-cohesive sediment, as a branch of water erosion, has been studied for decades, and criteria proposed in predicting incipient motion mainly focus on dimensionless shear stress and shear velocity. The two parameters could provide runoff erosive power, however, are invisible and not easy-measured in experiment. In this paper, critical runoff depth was recognized as another parameter, which is visible, measurable, and closely connected with shear velocity. To get it, a mathematical model coupling surface flow and subsurface flow was established, and they are governed by Navier‒Stokes equation and Brinkman‒extended Darcy equation, respectively. Velocity derived from the model could be indirectly applied in particle force analysis and finally a new criterion about critical runoff depth was obtained. Accuracy of the criterion was verified by comparison of experimental and theoretical values, e.g. theoretical critical runoff depth ranges from 2.71 ∼ 1.14 mm with a slope angle range of 20 ∼ 28° and mean particle diameter of 2.5 mm while the corresponding experiment values ranges from 3 ∼ 1 mm and the absolute errors are less than 0.3 mm. Compared with Yang’s formula, this criterion could also be applied in predicting incipient motion of non-cohesive sediment for its significant advantages of high accuracy and concise formulation.

Dry granular avalanche impact force on a rigid wall: Analytic shock solution versus discrete element simulations.

The present paper investigates the mean impact force exerted by a granular mass flowing down an incline and impacting a rigid wall of semi-infinite height. First, this granular flow-wall interaction problem is modeled by numerical simulations based on the discrete element method (DEM). These DEM simulations allow computing the depth-averaged quantities-thickness, velocity, and density-of the incoming flow and the resulting mean force on the rigid wall. Second, that problem is described by a simple analytic solution based on a depth-averaged approach for a traveling compressible shock wave, whose volume is assumed to shrink into a singular surface, and which coexists with a dead zone. It is shown that the dead-zone dynamics and the mean force on the wall computed from DEM can be reproduced reasonably well by the analytic solution proposed over a wide range of slope angle of the incline. These results are obtained by feeding the analytic solution with the thickness, the depth-averaged velocity, and the density averaged over a certain distance along the incline rather than flow quantities taken at a singular section before the jump, thus showing that the assumption of a shock wave volume shrinking into a singular surface is questionable. The finite length of the traveling wave upstream of the grains piling against the wall must be considered. The sensitivity of the model prediction to that sampling length remains complicated, however, which highlights the need of further investigation about the properties and the internal structure of the propagating granular wave.

An experimental investigation into Martian gully formation: a slush-flow model

Abstract To understand the potential applicability of the process of ‘slush flow’ (a sediment-carrying flow with water and ice) to gullies on Mars, we undertook a series of flume experiments at Earth surface temperatures and pressures, which we subsequently scaled for Mars. Experiments were conducted in a 3 × 0.5 m hinged flume filled with medium-grain-size sand. The experiments were performed over a slope angle range of 10°–30°, corresponding to the slope range for gullies observed on Mars. A water ice mix, or ‘slush’, was flowed through a 19 mm-diameter silicone hose and released onto the surface at the top of the slope. A variety of morphometric parameters were measured on each form produced in the flume. The forms produced in our experiments developed the three principal morphological components of Martian gullies: alcove, channel and apron, and had a diversity of planimetric forms. The forms produced during simulations compared well to slush flows in terrestrial arctic climates, and open up the possibility that some Martian gullies may result from slush flows associated with the thawing of permafrost-active layers or surface frost under favourable thermal regimes.

Front dynamics of elliptical gravity currents on a uniform slope

In the present investigation, we report data from direct numerical simulations of elliptical, finite release, Boussinesq gravity currents propagating down a uniform slope. The study comprises a series of simulations of elliptical gravity currents on a range of slope angles. The shape parameters are varied to study the effects of the initial cross-sectional aspect ratio (Λ0) and mean height to lock radius ratio (Γ) on the dynamics of the gravity current. It is found that the long-time development of the current spatial mass distribution is influenced by its initial shape at smaller slope angles (θ=5 and 10) whereas the long-time motion of the gravity current is relatively insensitive to its initial shape but is sensitive to the slope angle. The switching of axes are observed for all the noncircular releases studied in the present work. Multiple acceleration phases are observed for the current center of mass in the case of the current with a small or moderate initial cross-sectional aspect ratio (Λ0=0.1, 0.2, 0.5, 1, and 2) whereas one single acceleration phase exists for the current with a large initial cross-sectional aspect ratio (Λ0=5 and 10). The Froude numbers (Fr) for the currents released with the same slope angle but different initial shapes are observed to attain a similar constant value after the second acceleration phase. The mean Froude number (Fr) is seen to increase with increasing slope angles. The mean height to lock radius ratio is found to affect only the early development of the current with little influence on the long-time evolution.

Dry granular avalanche impact force on a rigid wall of semi-infinite height

The present paper tackles the problem of the impact of a dry granular avalanche-flow on a rigid wall of semi-infinite height. An analytic force model based on depth-averaged shock theory is proposed to describe the flow-wall interaction and the resulting impact force on the wall. Provided that the analytic force model is fed with the incoming flow conditions regarding thickness, velocity and density, all averaged over a certain distance downstream of the undisturbed incoming flow, it reproduces very well the time history of the impact force actually measured by detailed discrete element simulations, for a wide range of slope angles.

Pipe–soil interaction model for current-induced pipeline instability on a sloping sandy seabed

As offshore exploitation moves to deeper waters, ocean currents become the prevailing hydrodynamic loads on pipelines, and at the same time a sloping seabed is always encountered. The prediction of lateral soil resistance is vital in evaluating pipeline on-bottom stability. Unlike previous pipe–soil interaction models used mainly for horizontal seabed conditions, a pipe–soil interaction model for current-induced downslope and upslope instabilities is proposed by using the limit equilibrium approach. The Coulomb’s theory of passive earth pressure for the sloping seabed is incorporated in the derivation. The model verification with existing full-scale tests shows good agreement between the experimental results and predicted ones. Parametric study indicates that the effect of slope angle on pipeline lateral soil resistance is significant in the examined range of slope angle from –15° to 15°. The critical pipeline embedment and corresponding passive pressure decrease approximately linearly with increasing slope angle.

Experimental investigation of the effect of vegetation on soil, sediment erosion, and salt transport processes in the Upper Colorado River Basin Mancos Shale formation, Price, Utah, USA

Because of concerns about salinity in the Colorado River, this study focused on saline and sodic soils associated with the Mancos Shale formation with the objective of investigating mechanisms driving sediment yield and salinity loads and the role of vegetation in altering soil chemistry in the Price-San Rafael River Basin. Rainfall simulations using a Walnut Gulch rainfall simulator were performed at two study sites (Ferron and Price, Utah) across a range of slope angles and rainfall intensities to evaluate the relationship between sediment yield, salinity transport processes, and rainfall-induced changes in soil chemistry. Soil at Ferron had substantially greater salinity than Price as expressed in evaluated sodium absorption ratio, cation exchange capacity in soil, sediment, and total dissolved solids (TDS) in runoff. Principal component analysis and t-tests revealed that the two sites have different runoff and soil chemistry ions. Greater concentrations of K+, NO3−, and Cl− were present in soil-under-vegetation microsites compared to interspace soil areas. Soil soluble phase ions generally increased with depth and underwent vertical fluxes at rates proportional to rainfall intensity. Vegetation appears to have a protective effect on the soils from increasing rainfall intensity. Mat-forming saltbush found at Ferron was related most strongly to soil protection. The dissolution of sediment particles in runoff may be a key component of salinity transport processes on the Mancos Shale. Plot-averaged sediment and TDS had a positive linear relationship. The Rangeland Hydrology and Erosion Model successfully predicted TDS in runoff derived from these upland rangelands in central Utah.

Front dynamics and entrainment of finite circular gravity currents on an unbounded uniform slope

We report on the dynamics of circular finite-release Boussinesq gravity currents on a uniform slope. The study comprises a series of highly resolved direct numerical simulations for a range of slope angles between $5^{\circ }$ and $20^{\circ }$. The simulations were fixed at Reynolds number $Re=5000$ for all slopes considered. The temporal evolution of the front is compared to available experimental data. One of the interesting aspects of this study is the detection of a converging flow towards the centre of the gravity current. This converging flow is a result of the finite volume of the release coupled with the presence of a sloping boundary, which results in a second acceleration phase in the front velocity of the current. The details of the dynamics of this second acceleration and the redistribution of material in the current leading to its development will be discussed. These finite-release currents are invariably dominated by the head where most of the mixing and ambient entrainment occurs. We propose a simple method for defining the head of the current from which we extract various properties including the front Froude number and entrainment coefficient. The Froude number is seen to increase with steeper slopes, whereas the entrainment coefficient is observed to be weakly dependent on the bottom slope.

Experimental evidences and numerical modelling of runoff and soil erosion in flume tests

Rainfall causes runoff and soil erosion in artificial and natural slopes and important insight may derive from quantitative physically-based models or laboratory tests. Measurements of runoff and sediment discharges in small-scale experimental flume tests have become popular in recent years and a wide range of slope angles, soil grain-size-distributions and rainfall characteristics has been tested so far. In the literature, there are numerous studies dealing with a comparison between experimental data and model predictions using appropriate assumptions. However, there are still scientific gaps under complex experimental circumstances. The main goal is to discuss the performance of a physically-based numerical model in simulating well-documented runoff–erosion laboratory flume tests, also highlighting the uncertainties one may expect for real cases when applying numerical modelling of runoff and soil erosion to a real catchment.The paper deals with the numerical analysis of four experimental flume tests available in the literature, which investigate the erosion of bare gentle slopes due to constant-intensity rainfall; the behaviour of a steeper slope, bare or vegetated, under constant rainfall larger than in the previous experiments; the role of a sequence of different rainfall intensities (with the same cumulated rainfall), and different surface roughness in gentle slopes. Those experimental tests were simulated through LISEM, and the numerical results reproduce satisfactorily the global behaviour of the experimental plots eroded by artificial rainfall in all the four flume tests. As far as the ratio of the observed to the predicted peaks of water discharge and sediment concentration, the simulated peaks are very close to those observed in the laboratory experiments, except for low slope angle conditions where water discharge peak is overestimated and for one flume where sediment concentration peak is underestimated in two out of three cases. This analysis highlights that LISEM allows reasonably estimating the peak values of water and sediment discharge, which are generally used as design parameters of erosion control works. With reference to peak times of water discharge and sediment concentration, this paper highlights that LISEM has limitations in properly assessing the peak times of water discharge and sediment concentration; better results are, instead, expected when LISEM is used to simulate erosion and runoff on vegetated slopes. Globally, the results allow the assessment of the overall performance of the selected erosion model to correctly interpret the experimental evidences. As well, the discrepancies among the laboratory evidences and numerical results are discussed in relation to slope geometry and soil properties.

Rapid prediction of structural responses of double-bottom structures in shoal grounding scenario

This study presents a simplified analytical model for predicting the structural responses of double-bottom ships in a shoal grounding scenario. This solution is based on a series of analytical models developed from elastic-plastic mechanism theories for different structural components, including bottom girders, floors, bottom plating, and attached stiffeners. We verify this simplified analytical model by numerical simulation, and establish finite element models for a typical tanker hold and a rigid indenter representing seabed obstacles. Employing the LS-DYNA finite element solver, we conduct numerical simulations for shoal-grounding cases with a wide range of slope angles and indentation depths. In comparison with numerical simulations, we verify the proposed simplified analytical model with respect to the total energy dissipation and the horizontal grounding resistance. We also investigate the interaction effect of deformation patterns between bottom structure components. Our results show that the total energy dissipation and resistances predicted by the analytical model agree well with those from numerical simulations.

High-resolution simulations of non-Boussinesq downslope gravity currents in the acceleration phase

Gravity currents generated from an instantaneous buoyancy source of density contrast in the density ratio range of 0.3 ≤ γ ≤ 0.998 propagating downslope in the slope angle range of 0° ≤ θ &amp;lt; 90° have been investigated in the acceleration phase by means of high-resolution two-dimensional simulations of the incompressible variable-density Navier-Stokes equations. For all density contrasts considered in this study, front velocity history shows that, after the heavy fluid is released from rest, the gravity currents go through the acceleration phase, reaching a maximum front velocity Uf,max, followed by the deceleration phase. It is found that Uf,max increases as the density contrast increases and such a relationship is, for the first time, quantitatively described by the improved thermal theory considering the non-Boussinesq effects. Energy budgets show that, as the density contrast increases, the heavy fluid retains more fraction of potential energy loss while the ambient fluid receives less fraction of potential energy loss in the process of energy transfer during the propagation of downslope gravity currents. Previously, it was reported that for the Boussinesq case, the downslope gravity currents have a maximum of Uf,max at θ ≈ 40°. It is found, as is also confirmed by the energy budgets in this study, that the slope angle at which the downslope gravity currents have a maximum of Uf,max may increase beyond 40° as the density contrast increases.

A Multistage Technique to Minimize Overestimations of Slope Susceptibility at Large Spatial Scales

Rainfall induced landslides are one of the most frequent natural hazards on slanted terrains. They lead to significant economic losses and fatalities worldwide. Most factors inducing shallow landslides are local and can only be mapped with high levels of uncertainty at larger scales. This work presents an attempt to determine slope instability using buffer and threshold techniques to downscale large areas and minimize slope uncertainties at local scales, then in a second stage, logistic regression is used to determine susceptibility at large scales. ASTER GDEM V2 is used for topographical characterization of slope and buffer analysis. Four static parameters (slope angle, soil type, land cover and elevation) for 230 shallow rainfall-induced landslides listed in a comprehensive landslide inventory for the continental United States are examined. A delimiting buffer equivalent to 5, 25 or 50 km is created around each landslide event facilitating the statistical analysis of slope thresholds. Slope angle thresholds at the pixel points 50, 75, 95, 99 and maximum percentiles are compared to one another and tested for best fit in a logistic regression environment. It is determined that values lower than the 75-percentile threshold misrepresents susceptible slope angles by not including slopes higher than 35°. Best range of slope angles and regression fit can be achieved when utilizing the 99 percentile slope angle threshold. The resulting logistic regression model predicts the highest number of cases correctly with 97.2% accuracy. The logistic regression model is carried over to ArcGIS where all variables are processed based on their corresponding coefficients. A regional landslide probability map for the continental United States is created and analyzed against the available landslide records and their spatial distributions. It is expected that future inclusion of dynamic parameters like precipitation and other proxies like soil moisture into the model will further improve accuracy. Keywords: Shallow landslides; Slope instability; Threshold analysis; Logistic regression; Regional analysis; GIS; Remote sensing Introduction Rainfall induced landslides are one of the most frequent natural hazards on slanted terrains. They usually result in great economic losses and fatalities globally. Worldwide at least 32,322 deaths between 2004 and 2010 have been reported [1] and in the United States alone, landslides cause $1-2 billion in damages and more than 25 fatalities in average each year [2]. Understanding, mapping, modeling and preventing the aftermath of these devastating events represents an important scientific and operational endeavor [3]. The term “Landslide” describes the downward and outward movement of slope-forming materials that include rock, earth, and debris or a combination of these [4]. Although landslides are considered to be dependent on the complex interaction of several static and dynamic factors [5-7] slope angle has great influence on the susceptibility of a slope to sliding. Increased slope angle usually correlates to increased likelihood of failure even if the material distribution on the slope is uniform and isotropic [5]. Undeniably, many other parameters are essential to the analysis of landslide risk. For example, changes in land use and land cover such as deforestation, forest logging, road construction, cultivation and fire on steep slopes can have a significant effect on landslide activity [8]. In addition, forest vegetation