Remote sensing interpretation of debris flow material sources and its distribution characteristics in Miancu gully after Wenchuan earthquake

2011 ◽  
Author(s):  
Pengcheng Su ◽  
Bintao Liu ◽  
Zunlan Cheng ◽  
Yan Zhao
Keyword(s):  
Remote Sensing ◽  
Debris Flow ◽  
Wenchuan Earthquake ◽  
Distribution Characteristics ◽  
Material Sources ◽  
Remote Sensing Interpretation

scholarly journals Remote Sensing Investigation of Geological Hazards in Xingguo County, Jiangxi Province

2019 ◽  
Vol 131 ◽  
pp. 01056
Author(s):  
Min Yu ◽  
Jiangqin Chao
Keyword(s):  
Remote Sensing ◽  
Debris Flow ◽  
Jiangxi Province ◽  
Landsat 8 ◽  
Geological Environment ◽  
Geological Disasters ◽  
Work Area ◽  
Ground Collapse ◽  
Geological Disaster ◽  
Remote Sensing Interpretation

Xingguo County is located in the middle and low hilly mountainous areas. The area of the landslide, collapse and debris flow geological disasters is large. The sudden geological disasters such as landslides and mudslides caused by heavy rainfall are increasing year by year. This study mainly used high-altitude aerial imagery (0.5m) and Landsat 8 OLI satellite imagery covering Xingguo County as the data source, carried out remote sensing interpretation of geological environment background conditions and geological disasters in the whole area, and carried out on-site verification. At the same time, the correlation between the stratigraphic structure, topography and other factors in the study area and the spatial distribution characteristics of geological disaster points are discussed. The results show that: (1) based on remote sensing image interpretation of 377 geological disaster points; 83 landslide points, 229 hidden danger points, 17 collapse points, 26 hidden danger points, 1 hidden danger point, ground collapse point 1 At 20 places in the geological environment. (2) From the results of remote sensing interpretation, the types of geological disasters in the work area are mainly landslides and landslide hazards (including collapse type), and there are fewer collapses, collapses and debris flow hazards, and most landslide hazard points are unstable. (3) From the distribution of geological disasters, it is mainly within the scope of artificial influence. The construction of excavation slopes on the roads leads to instability of the slopes and induces disasters under the influence of rainfall. In addition, there are a large number of artificial mining mines in the work area. These places are also prone to geological disasters due to unreasonable mining and subsequent prevention and control work. (4) Areas with strong human activities, areas near the fault structure and water system roads are the main influencing factors for geological disasters in the work area.

Structural geometry of Ikogosi warm spring, southwestern Nigeria: evidence from aeromagnetic and remote sensing interpretation

2021 ◽  
Vol 7 (2) ◽  
Author(s):  
Naheem Banji Salawu ◽  
Julius Ogunmola Fatoba ◽  
Leke Sunday Adebiyi ◽  
Akinola Bolaji Eluwole ◽  
Nurudeen Kolawole Olasunkanmi ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Structural Geometry ◽  
Southwestern Nigeria ◽  
Warm Spring ◽  
Remote Sensing Interpretation

Granular effect on debris flow rheology

2021 ◽  
Author(s):  
Taiqiang Yang
Keyword(s):  
Shear Rate ◽  
Debris Flow ◽  
Debris Flows ◽  
Shear Thinning ◽  
Dynamical Equations ◽  
Real Rate ◽  
The Real ◽  
Jiangjia Gully ◽  
Material Sources ◽  
Surge Phenomena

<p>Debris flow is characterized by the multi-disperse grain composition and intergranular collision and friction, but the granular effects on rheology are often reduced to the volumetric concentration of solid (C<sub>v</sub>), almost ignoring the specific grain size distribution (GSD). In this study, small debris flows occurring in a tributary of Jiangjia Gully were taken as the material sources for rheology experiments. From the real flows we selected slurries with different C<sub>v</sub> and maximum grain sizes (D<sub>m</sub>) for rheological tests under shearing rate up to 40 (s<sup>-</sup><sup>1</sup>), which is usually the real rate for debris flows in natural conditions. The results indicate that the flows follow the Herschel-Bulkley (HB) rheology, with randomly changing consistency coefficient and relatively constant exponent of 0.45 on average. Only at high shear rate will the flow exhibit Bingham behavior. The HB rheology also reveals shear thinning behavior in surge phenomena observed in the field. Shear-thinning behavior is revealed by the viscosity-shear rate relationship: η<sub>a</sub>=pγ<sup>q</sup>, with the exponent (thinning index) dependent on shear rate. This greatly concerns the surge phenomena observed in field. Moreover, both the yield stress and the effective viscosity are found to be perfectly related to the scaling GSD parameters in power-law and exponential form, with nearly constant exponents independent of the shear rate(Figure 1). The rheology properties can be calculated from their relationships to GSD parameters (μ, D<sub>c</sub>), which in turn can be used to infer the HB rheology for the concerned flows and then build the dynamical equations(Figure 2). This implies the presence of some interlock between the fine and coarse grains. Finally the rheology model (general in HB form) can be completely determined by the GSD parameters. This study has for the first time proposed quantitative formulas for rheology incorporating GSD parameters, which is helpful for more accurate dynamic analysis of debris flow.</p>

scholarly journals Application and analysis of debris-flow early warning system in Wenchuan earthquake-affected area

2016 ◽  
Vol 16 (2) ◽  
pp. 483-496 ◽  
Author(s):  
D. L. Liu ◽  
S. J. Zhang ◽  
H. J. Yang ◽  
L. Q. Zhao ◽  
Y. H. Jiang ◽  
...  
Keyword(s):  
Debris Flow ◽  
Wenchuan Earthquake ◽  
Early Warning ◽  
Early Warning System ◽  
Prediction Accuracy ◽  
Warning System ◽  
Sichuan Province ◽  
Affected Area ◽  
The Wenchuan Earthquake ◽  
New System

Abstract. The activities of debris flow (DF) in the Wenchuan earthquake-affected area significantly increased after the earthquake on 12 May 2008. The safety of the lives and property of local people is threatened by DFs. A physics-based early warning system (EWS) for DF forecasting was developed and applied in this earthquake area. This paper introduces an application of the system in the Wenchuan earthquake-affected area and analyzes the prediction results via a comparison to the DF events triggered by the strong rainfall events reported by the local government. The prediction accuracy and efficiency was first compared with a contribution-factor-based system currently used by the weather bureau of Sichuan province. The storm on 17 August 2012 was used as a case study for this comparison. The comparison shows that the false negative rate and false positive rate of the new system is, respectively, 19 and 21 % lower than the system based on the contribution factors. Consequently, the prediction accuracy is obviously higher than the system based on the contribution factors with a higher operational efficiency. On the invitation of the weather bureau of Sichuan province, the authors upgraded their prediction system of DF by using this new system before the monsoon of Wenchuan earthquake-affected area in 2013. Two prediction cases on 9 July 2013 and 10 July 2014 were chosen to further demonstrate that the new EWS has high stability, efficiency, and prediction accuracy.

scholarly journals Analysis of a debris flow after Wenchuan Earthquake and discussion on preventive measures

2019 ◽  
Vol 23 (3 Part A) ◽  
pp. 1563-1570
Author(s):  
Zhi-Long Zhang ◽  
Jing Xie ◽  
De-Ke Yu ◽  
Zhi-Jie Wen
Keyword(s):  
Debris Flow ◽  
Wenchuan Earthquake ◽  
Preventive Measures ◽  
Impact Force ◽  
Site Investigation ◽  
The Wenchuan Earthquake ◽  
Formation Conditions ◽  
National Road ◽  
And Control ◽  
Debris Flow Disaster

This paper addresses a debris flow disaster in Yingxiu town after the Wenchuan earthquake. Through site investigation and data review, the geography and geological environment of the basin and the development, formation conditions and activity characteristics of the debris flow in the basin are analyzed. Calculate and analyze the characteristics of the debris flow, such as gravity, flow velocity and impact force. According to the management idea of combination of blocking and discharging, this paper proposes to arrange three blocking dams in the main ditch, construct drainage gullies in the downstream accumulation section, and prevent and control the aqueduct in the intersection of the main ditch and the G213 national road, which will be similar to the earthquake in the future. It is provided as a reference for research and prevention of the debris flow.

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