scholarly journals Understanding rockfalls along the national road G318 in China: from source area identification to hazard probability simulation

2021 ◽  
Author(s):  
Lixia Chen ◽  
Yu Zhao ◽  
Yuanyao Li ◽  
Lei Gui ◽  
Kunlong Yin ◽  
...  
Keyword(s):  
Slope Angle ◽  
Source Area ◽  
Field Investigation ◽  
Slope Aspect ◽  
Multivariate Logistic Regression Model ◽  
Potential Hazard ◽  
Rockfall Hazard ◽  
Source Areas ◽  
Slope Structure ◽  
National Road

Abstract. Rockfall hazard is frequent along the national road (G318) in west Hubei, China. To understand the distribution and potential hazard probability, this study combines the result of a 3-years engineering geological investigation, statistical modeling, and kinemics-based method to identify risky road sections. Rockfall hazard probability is calculated by integrating spatial, temporal, size probability, and reaching probabilities of source areas. Rockfall source areas are preliminarily identified first by slope angle threshold (SAT) analysis. Random Forest model (RFM) and multivariate logistic regression model (MLRM) are then applied and compared to get the final susceptible source areas, considering eight factors, including slope, aspect, elevation, lithology, joint density, slope structure, land-use type, distance to the road. Temporal and size probability of source areas are separately obtained by Poisson distribution and power-law distribution theory. An important parameter (reach angle) for rockfall trajectory simulation was determined by back analysis in Flow-R and validated by field investigation. The results show good fitness with the measurements by field investigation. In the conditions of 5, 20, and 50 years return period, potential risky road sections are found out under two size scenarios (larger than 1 000 m3, 10 000 m3). This research helps the local government to completely understand the rock falls from source area existence and potential risk to roads.

scholarly journals Landslides susceptibility modelling using Multivariate Logistic Regression Model in the Sahla Watershed in Northern Morocco

2021 ◽  
Vol 33 ◽  
Author(s):  
Mohammed El-Fengour ◽  
Hanifa El Motaki ◽  
Aissa El Bouzidi
Keyword(s):  
Logistic Regression ◽  
Landslide Susceptibility ◽  
Slope Angle ◽  
Google Earth ◽  
Slope Aspect ◽  
Multivariate Logistic Regression Model ◽  
Susceptibility Map ◽  
Potential Hazard ◽  
Topographic Wetness Index ◽  
Landslide Occurrence

This study aimed to assess landslide susceptibility in the Sahla watershed in northern Morocco. Landslides hazard is the most frequent phenomenon in this part of the state due to its mountainous precarious environment. The abundance of rainfall makes this area suffer mass movements led to a notable adverse impact on the nearby settlements and infrastructures. There were 93 identified landslide scars. Landslide inventories were collected from Google Earth image interpretations. They were prepared out of landslide events in the past, and future landslide occurrence was predicted by correlating landslide predisposing factors. In this paper, landslide inventories are divided into two groups, one for landslide training and the other for validation. The Landslide Susceptibility Map (LSM) is prepared by Logistic Regression (LR) Statistical Method. Lithology, stream density, land use, slope curvature, elevation, topographic wetness index, slope aspect, and slope angle were used as conditioning factors. The Area Under the Curve (AUC) of the Receiver Operating Characteristic (ROC) was employed to examine the performance of the model. In the analysis, the LR model results in 96% accuracy in the AUC. The LSM consists of the predicted landslide area. Hence it can be used to reduce the potential hazard linked with the landslides in the Sahla watershed area in Rif Mountains in northern Morocco.

scholarly journals Rockfall Investigation and Hazard Assessment from Nang County to Jiacha County in Tibet

2019 ◽  
Vol 10 (1) ◽  
pp. 247 ◽  
Author(s):  
Haiyang Liu ◽  
Xueliang Wang ◽  
Xiaohui Liao ◽  
Juanjuan Sun ◽  
Su Zhang
Keyword(s):  
Rock Mass ◽  
Hazard Assessment ◽  
Cloud Model ◽  
Rapid Development ◽  
Slope Angle ◽  
Project Planning ◽  
Aerial Images ◽  
Slope Aspect ◽  
Human Engineering ◽  
Rockfall Hazard

The influences of rockfall on human engineering have been increasing in Tibet with the rapid development of the western region of China. This study proposed a multi-approach to carry out rockfall investigation and hazard assessment. As a case study, the rockfall hazard from Nang County to Jiacha County in Tibet was assessed. Firstly, we summarized the characteristics of spatial distributions of typical rockfall sources using Digital Elevation Model (DEM) and unmanned aerial vehicle (UAV) aerial images with resolution of 10 m. According to the thresholds of slope angle, slope aspect and elevation distribution of typical rockfall sources, we obtained all of the rockfall source areas in study area semi-automatically in ArcGIS platform. Secondly, we improved the efficiency and accuracy of detailed field investigation by using a three-dimensional (3D) point cloud model and rock mass structure extraction software. According to the analysis result, the dominant joint set was J1, whose orientation was basically consistent with the Yarlung Tsangpo Fault. The combination of J1, J2 and J4 cut the rock mass into blocks of wedge with J1 as potential sliding planes. It was indicated that the stability of the rock mass in study area was mainly controlled by the characters of joint sets. Finally, we applied the improved reclassification criteria of the Rockfall Hazard Vector (RHV) method in rockfall hazard assessment according to protection capabilities of the current protection facilities, making the result more valuable for geohazards prevention work. Based on this multi-approach, we obtained that 10.92% of the 306 provincial highway and 9.38% of the power line were threatened by potential rockfall hazards in study area. The hazard assessment results of study area were also of certain guiding value to the linear project planning and geohazards prevention work.

Probabilistic identification of rockfall source areas: an example from El Hierro island (Canary Island, Spain)

2020 ◽  
Author(s):  
Mauro Rossi ◽  
Roberto Sarro ◽  
Paola Reichenbach ◽  
Rosa María Mateos
Keyword(s):  
Probabilistic Approach ◽  
Slope Angle ◽  
Source Area ◽  
Recent Event ◽  
Source Areas ◽  
El Hierro ◽  
The Road ◽  
Thematic Information ◽  
Steep Topography ◽  
Geological Complexity

<p>Rockfalls are the most frequent and dangerous instability phenomena in mountainous areas, causing high economic and social damages. Rockfalls are triggered by complex instability mechanisms and the source areas are controlled by environmental factors like geology, the presence of discontinuities and slope angle. Modeling rockfall phenomena is complex and requires diversified input including parameters controlling the boulders trajectories and the source areas identification.</p><p>In the Canary Islands, the steep topography and the geological complexity influence the activation of slope dynamics and the occurrence of slope failures. In particular, rockfalls are very common and they represent a major threat to society, costing lives, disrupting infrastructures and destroying livelihoods. In 2011 the volcanic crisis in El Hierro Island triggered numerous rockfalls that affected the road network causing a great social alarm.</p><p>After the recent event, we have attempted to identify rockfall source areas using different approaches including probabilistic modeling. The probabilistic approach applies a combination of multiple statistical models and requires a map of the observed source areas as dependent variable and a set of thematic information as independent variables (e.g., morphometric parameters derived from DTM, lithological information that considers the mechanical behavior of the rocks). For the purpose, we have identified various scenarios selecting different training and validation zones and evaluating for each scenario the associated errors. The maps resulting from the models, provide for the whole El Hierro Island, the probability of a pixel being a source area and can be used as input for the rockfall modeling.</p>

scholarly journals GIS-based rockfall hazard zones modeling along the coastal Gulf of Aqaba Region, Egypt

2021 ◽  
Author(s):  
Adel Omran ◽  
Kanij Fahmida ◽  
Dietrich Schröder ◽  
Mohamed O. Arnous ◽  
Ahmed E. El-Rayes ◽  
...  
Keyword(s):  
High Reliability ◽  
Focal Depth ◽  
Google Earth ◽  
Geographical Information ◽  
Gulf Of Aqaba ◽  
Slope Aspect ◽  
Economic Damage ◽  
Potential Hazard ◽  
Hazard Zonation ◽  
Rockfall Hazard

AbstractRockfall is a natural hazard in mountainous areas not to be underestimated. Mass activities differing in rock volume may cause considerable economic damage. Accomplishing qualitative appraisal of high-potential zones for rockfall is a first step towards implementing mitigation strategies. Nowadays, Geographical Information Systems (GIS) are the state-of-the-art tool for a fast and economic approach of identifying potential hazard zones rather than using conventional mapping with in-situ field data. Primarily, current research focuses on designing and implementing user-friendly tools delineating potential rockfall hazard zonation (RHZ). The constructed model examines triggering factors like slope, aspect, elevation, lithology, structural lineament, rainfall intensity, and seismic activity focal depth of a mountainous coastal region (Gulf of Aqaba, Egypt). The extracted geomorphological parameters were based on a high-resolution TanDEM-X Digital Elevation Model. The enhanced Landsat ETM + 7 was used to generate the lithological and structural lineament parameters, while the rainfall data were collected from NASA project tool. The zonation model was implemented by means of ESRI’s ArcGIS Pro ModelBuilder. Google Earth Pro orthophotos compared with the generated rockfall hazard zonation map indicate the potential RHZ with high reliability. The achieved results show that 15 % of the study area qualifies as a high rockfall hazard zone. As the RHZs generated by the model depend on the input data and the selected rating scores and weights, obtaining ground truth is essential to get a trustworthy result. Finally, this study recommends employing the built RHZ model on similar terrains worldwide to support decision-makers involving any sustainable development projects.

scholarly journals Identification of rockfall source areas using the seed cell concept and bivariate susceptibility modelling

2021 ◽  
Author(s):  
Aleksandar Toševski ◽  
Davor Pollak ◽  
Dario Perković
Keyword(s):  
Land Cover ◽  
Source Area ◽  
Slope Aspect ◽  
Ratio Method ◽  
Susceptibility Map ◽  
Contributing Factors ◽  
Corine Land Cover ◽  
Source Areas ◽  
Geological Map ◽  
Seed Cell

AbstractThe objective of this research was to prepare a rockfall susceptibility map. Explorations were conducted in the Dubračina River basin (Croatia). The input data included a geological map, an orthophoto and a 1-m digital terrain model (DTM). After a talus inventory was prepared, the seed cell concept was applied to define the rockfall source areas. The contributing factors (predictors) of rockfalls were evaluated by the chi-squared test. The analysis confirmed the following predictors: CORINE land cover, lithology, slope, aspect, distance from a spring, distance from a road, distance from a fault, distance from a stream, and distance from the rock-soil geological boundary. A matrix pairwise comparison of the predictor ratings was used to define the most significant contributing factors. The predictors that affected the susceptibility map in the share of 86.3% were the slope (61.6%), lithology (13.4%), CORINE land cover (6.2%), and distance from the rock-soil geological boundary (5.1%). Two susceptibility maps were prepared: one using all nine contributing factors and another using the four most significant factors. The analysis showed that both maps were good, with the same areas under the receiver operating characteristic (ROC) curves. The map prepared with only four contributing factors can be considered a better map due to its more precise spatial definition of critical areas. It can be concluded that geological map, 1-m DTM and orthophoto provide enough data to prepare reliable rockfall susceptibility map. The application of the bivariate statistical zonation method called the “frequency ratio method” was proven to be successful. This research demonstrates that the application of the seed cell concept can be useful to speed up the process of rockfall source area detections in large research regions.

scholarly journals L'inventaire forestier comme méthode de caractérisation spatiale de l'aléa chute de pierres

2019 ◽  
Vol 170 (2) ◽  
pp. 78-85 ◽  
Author(s):  
Robin Mainieri ◽  
Jérôme Lopez-Saez ◽  
Christophe Corona ◽  
Markus Stoffel ◽  
Eric Mermin ◽  
...  
Keyword(s):  
Source Area ◽  
Historical Records ◽  
Systematic Mapping ◽  
Mountain Areas ◽  
Rockfall Hazard ◽  
Source Areas ◽  
Breast Height ◽  
Hazard Zoning ◽  
Tree Data ◽  
Rockfall Protection

The contribution of tree inventories to the spatial characterisation of the rockfall hazard Rockfall is one of the most frequent natural hazards in mountain areas. The characterisation of rockfall activity in terms of frequency, intensity (energy) and dispersion (run-out distance) is essential for risk management, but is extremely complex due to the diffuse nature of this hazard and the gaps in historical records. In this study we show that trees can be reliable bioindicators to reconstruct rockfall activity. Our method is based on the combination of a systematic mapping of all trees (location, breast height diameter, species) and the complete recording of all visible scars. On an area of one hectare in the municipality of Saint-Guillaume (Vercors massif, French Alps) we recorded 793 trees and 2333 scars. The spatial distribution of the tree species and scars was used to locate the most active source areas and the most important rockfall trajectories and to show the decreasing rockfall activity with increasing distance to the source area and thus also the protective effect of the forest. The approach is particularly valuable in areas where historical records are lacking. It can be used in the future to 1) refine hazard zoning and 2) calibrate rockfall models. Thanks to the recorded tree data, the area could also be used as a marteloscope for practicing silvicultural interventions in the rockfall protection forest.

scholarly journals An efficient semi-distributed hillslope erosion model for the subhumid Ethiopian Highlands

2013 ◽  
Vol 17 (3) ◽  
pp. 1051-1063 ◽  
Author(s):  
S. A. Tilahun ◽  
C. D. Guzman ◽  
A. D. Zegeye ◽  
T. A. Engda ◽  
A. S. Collick ◽  
...  
Keyword(s):  
Surface Runoff ◽  
Source Area ◽  
Sediment Concentration ◽  
Erosion Model ◽  
Ethiopian Highlands ◽  
Source Areas ◽  
Blue Nile Basin ◽  
Field Evidence ◽  
Sediment Loss ◽  
Main Variable

Abstract. Erosion modeling has been generally scaling up from plot scale but not based on landscape topographic position, which is a main variable in saturation excess runoff. In addition, predicting sediment loss in Africa has been hampered by using models developed in western countries and do not perform as well in the monsoon climate prevailing in most of the continent. The objective of this paper is to develop a simple erosion model that can be used in the Ethiopian Highlands in Africa. We base our sediment prediction on a simple distributed saturated excess hydrology model that predicts surface runoff from severely degraded lands and from bottom lands that become saturated during the rainy season and estimates interflow and baseflow from the remaining portions of the landscape. By developing an equation that relates surface runoff to sediment concentration generated from runoff source areas, assuming that baseflow and interflow are sediment-free, we were able to predict daily sediment concentrations from the Anjeni watershed with a Nash–Sutcliffe efficiency ranging from 0.64 to 0.78 using only two calibrated sediment parameters. Anjeni is a 113 ha watershed in the 17.4 million ha Blue Nile Basin in the Ethiopian Highlands. The discharge of the two watersheds was predicted with Nash–Sutcliffe efficiency values ranging from 0.80 to 0.93. The calibrated values in Anjeni for degraded (14%) and saturated (2%) runoff source area were in agreement with field evidence. The analysis suggests that identifying the runoff source areas and predicting the surface runoff correctly is an important step in predicting the sediment concentration.

scholarly journals Technical Note: Preliminary estimation of rockfall runout zones

2011 ◽  
Vol 11 (3) ◽  
pp. 819-828 ◽  
Author(s):  
M. Jaboyedoff ◽  
V. Labiouse
Keyword(s):  
Slope Angle ◽  
Digital Terrain Model ◽  
Grid Cell ◽  
Technical Note ◽  
Field Observations ◽  
Source Areas ◽  
Terrain Model ◽  
Digital Terrain ◽  
Energy Line ◽  
Potential Source

Abstract. Rockfall propagation areas can be determined using a simple geometric rule known as shadow angle or energy line method based on a simple Coulomb frictional model implemented in the CONEFALL computer program. Runout zones are estimated from a digital terrain model (DTM) and a grid file containing the cells representing rockfall potential source areas. The cells of the DTM that are lowest in altitude and located within a cone centered on a rockfall source cell belong to the potential propagation area associated with that grid cell. In addition, the CONEFALL method allows estimation of mean and maximum velocities and energies of blocks in the rockfall propagation areas. Previous studies indicate that the slope angle cone ranges from 27° to 37° depending on the assumptions made, i.e. slope morphology, probability of reaching a point, maximum run-out, field observations. Different solutions based on previous work and an example of an actual rockfall event are presented here.

scholarly journals How Can Geomorphology Inform Ecological Restoration? A Synthesis of Geophysical and Biological Assessment to Determine Restoration Priorities

2021 ◽  
Author(s):  
◽  
Leicester Cooper
Keyword(s):  
Land Use ◽  
Ecological Restoration ◽  
Reference Site ◽  
Slope Angle ◽  
Slope Aspect ◽  
Total N ◽  
Olsen P ◽  
Restoration Site ◽  
Soil Variables ◽  
Indigenous Forest

<p>The central concern that this study addresses is how an understanding of geomorphological processes and forms may inform ecological restoration; particularly practical restoration prioritisation. The setting is that of a hill country gully system covered in grazing pasture which historically would have been cloaked in indigenous forest. The study examines theory in conjunction with an application using a case study centred on Whareroa Farm (the restoration site) and Paraparaumu Scenic Reserve (the reference site) on the southern Kapiti Coast, north of Wellington. The impact that the change of land use has had on the soil and geomorphic condition of Whareroa and the influence the changes may have on the sites restoration is investigated. The thesis demonstrates a method of choosing reference sites to be used as templates for rehabilitating the restoration site. Geographical Information Systems and national databases are used and supplemented with site inspection. The reference site chosen, Paraparaumu Scenic Reserve, proved to be a good template for the restoration site particularly given that it is located in the midst of a heavily modified area. On-site inspection considering dendritic pattern and floristic composition confirms the database analysis results. Soil variables (bulk density, porosity, soil texture, pH, Olsen P, Anaerobic Mineralisable N, Total N (AMN), Total C and C:N ratio) are investigated and statistical comparisons made between the sites to quantify changes due to land-use change, i.e. deforestation and subsequent pastoral grazing. Factors investigated that may explain the variation in the soil variables were site (land use), hillslope location, slope aspect, and slope angle. Permutation tests were conducted to investigate the relationships between the independent factors and the SQI (dependent soil variables). Land use and slope angle were most frequent significant explanatory factors of variation, followed by hillslope location whilst slope aspect only influenced soil texture. A number of soil variables at Whareroa were found to be outside the expected range of values for an indigenous forest soil including AMN, Total N, Olsen P, and pH ...</p>

scholarly journals An 1-D Integrated Hydro-Mechanical Model to Unravel Different Hydrological Triggering Processes of Debris Flows

2018 ◽  
Author(s):  
Theo W.J. van Asch ◽  
Bin Yu ◽  
Wei Hu
Keyword(s):  
Mechanical Model ◽  
Debris Flows ◽  
Overland Flow ◽  
Model Simulation ◽  
Slope Angle ◽  
Great Influence ◽  
Source Area ◽  
Material Model ◽  
Flume Experiments ◽  
Bed Material

Many studies, which try to analyze the meteorological threshold conditions for debris flows ignore the type of initiation. This paper focuses on the differences in hydrological triggering processes of debris flows in channel beds of the source areas. The different triggering processes were studied in the laboratory and by model simulation on the field scale. The laboratory experiments were carried out in a flume, 8 m long and a width of 0.3 m. An integrated hydro-mechanical model was developed, describing Hortonian and Saturation overland flow, through flow, maximum sediment transport and failure of bed material. The model was tested on the processes observed in the flume. The flume experiments show a sequence of hydrological processes triggering debris flows, namely erosion and transport by intensive overland flow and by infiltrating water causing failure of channel bed material. Model simulations carried out on a schematic hypothetical source area of a catchment show that the type and sequence of these triggering processes are determined by slope angle and the hydraulic conductivity of the bed material. It was also clearly demonstrated that the type of initiation process and the geometrical and hydro-mechanical parameters may have a great influence on rainfall intensity-duration threshold curves, indicating the start of debris flows.

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