Distribution Characteristics of Debris Flows and Landslides in Three Rivers Parallel Area

Ding Mingtao1* and Wei Fangqiang 2

The Three Rivers Parallel area lies in the transition zone between the first and second-order geomorphologic ladder, where the disasters of debris flows and landslides often occur, causing huge losses of life and property. The main characteristics of debris flows and landslides in the Three Rivers Parallel area are studied in this paper. Data on 1352 debris flow gullies and 487 typical landslides in the area have been recorded. The distribution density of the debris flow in the study region is 1.12 ditches per 100 km2. A method that combines field survey and remote sensing is adopted. Characteristics, including environmental background, distribution and cause of the debris flows and landslides in the Three Rivers Parallel area are further investigated. The debris flow gullies and typical landslides are mainly distributed in the transition zone of geomorphic units, fault and quake zones, large relative reliefs and severely destroyed vegetation zones. The formation factors of debris flows and landslides disaster are mainly affected by landform, geological structure, climate, hydrology and human activities.

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Lineaments Controlled Landslides of Nilgiri Mountains, India -A Geospatial Analysis

Muthukumar M.

As landslides are mostly witnessed in mountains of severe anthropogenic activities, scientists and technocrats were of the general opinion that improper interaction of humans with the mountainous ecosystems is the prime cause for the landslides. But the geoscientists have made several observations that geological processes and related land systems assign different grades of landslide vulnerabilities to the terrain systems and rainfall or the other anthropogenic variables act only as triggering parameters. The present GIS based study carried out between various derivatives of lineaments like frequency, density, intersection density and the landslides indicated the definite contribution of tectonic grains over landslides.

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Effect of Gas Pressure on the Transport Properties of Outburst-Prone Coal

Gun Huang,1,2 Guangzhi Yin1,2* and Xiaoshuang Li1

It is generally believed that some areas of a coalfield prone to gas and coal outbursts are characteristic of high gas contents, high in situ stress, special geological structures and low permeability. The mechanism of gas and coal outbursts remains a major problem facing the rock mechanics and rock engineering community. To investigate the impact of gas pressure on the permeability of coals characteristic of gas and coal outbursts from Datong No.1 coal mine, Chongqing in Southwestern China, a new apparatus was designed and fabricated and a series of experiments have been performed. The test results show that the methane flow rate through outburst-prone coal proportionally increases with gas pressure under constant axial and confining pressures. The methane flow rate through coals can be related to gas pressure. The difference of seepage force between the ends of coal samples inversely increases with gas pressure and finally almost vanishes at a certain higher pressure, which leads to the coal permeability coming to a limit.

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Geo-Information technology for mass wasting hazard zonation : Central - west Alborz – Iran

Farrokhnia A.R.,1* Pirasteh S.,2 Pourkermani M.3 and Arian M.4

Central – west Alborz in Iran is a significant example of very high potential for natural disaster which results from inversion and reactivation of pre-existing structures inherited from the long and complex evolution of this segment of the Alpine Himalayan orogenic system. Spatial and temporal multi-layered information is required to assess the natural hazard susceptibility in the mountainous regions. The aim of this study is to operate a working methodology wherein geo-environmental parameters are analyzed to develop models for mass wasting hazard zonation areas using Geo information technology (GIT). This study has incorporated historical data, filed study, GIS, RS and GPS to help predict hazard zone. This research tries to extract the factors such as lineaments and faults, vegetation, lithology, slope, drainage, land use/land cover, seismicity and roads network using geo-information technology.

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Seismic Bearing Capacity Factors for Shallow Strip Footings by Pseudo-Dynamic Approach

Ghosh Priyanka 1* and Choudhury Deepankar 2

Computation of seismic bearing capacity factors is very important for the design of the shallow strip footings as the failure of footings under earthquake condition could be disastrous. In literature, mostly the pseudo-static approach was used by various researchers to compute the seismic bearing capacity factors. But the conventional pseudo-static approach ignores the dynamic nature of earthquake force with variation of time, frequency, body waves etc. In this paper, seismic bearing capacity is obtained for shallow strip footings in cohesionless soil, by using the recent pseudo-dynamic approach, which considers the effects of both shear and primary waves, soil amplification, duration and period of lateral shaking. Using the limit equilibrium method, the values of the seismic bearing capacity factors with respect to unit weight and surcharge (Nγd and Nqd) are found out for various values of soil friction angles, soil amplifications and seismic acceleration coefficients both in the horizontal and vertical directions. Results of the present study are reported in both the graphical and tabular form for the practical use in design. It is observed that with increase in seismic accelerations and amplification factor, seismic bearing capacity factors decrease significantly and more so for denser soils. Comparisons of the proposed method with available theories in the seismic case are also presented.

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The north of Iran fire regimes assessment with MODIS fire data: their relationship to PNPI and temperature (2001-2008)

Ardakani Ali S., Valadan Zoej Mohammad J., Mohammadzadeh Ali* and Mansourian Ali

Fires in vegetation, forests, woodlands and rangelands are a major and continuing threat to human life, health and livelihoods, to economic development and to the environment. From an ecological point of view, fire is one of the important disasters that contribute in deforestation and destroying land cover vegetation in the global and local scales. Remote sensing provides rapid and valuable data for fire management. The Moderate Resolution Imaging Spectroradiometer (MODIS) has been designed to include specific characteristics for fire detection. MODIS for forest fire monitoring has high detection accuracy, high radiometric resolution, moderate spatial resolution modes and a high saturation level. Fires occur repeatedly in Iranian forests during the summer time. According to the Food and Agriculture Organization (FAO) reports, 0.06 percent of Iran's forests burn every year. This paper provides spatial and temporal analysis of fires occurred in the northern forests of Iran in relation with PNPI and temperature from 2001-2008. Fire season in the northern part of Iran is from May until the end of October. Most of these fires occurred in the eastern regions of the Mazandaran Sea. The fire frequency has a correlation of 0.48 with percent of normal precipitation index (PNPI) values. Also temporal analysis from 2001-2008 shows that most of the fires occurred in June.

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Strong signal of the super-huge flood and superposition effect of physical factors - A case study along Yangtze River of China in 1954

Feng L. H.

Based on current available studies and radar data, the major physical factors on the formation of the super-huge flood along Yangtze River in 1954 include: (1) Sunspot activity, (2) The El Nino event, (3) A strong earthquake in the south of Qinghai-Tibetan Plateau, (4) A solar eclipse, (5) The cross eclipse year of perihelion, (6) Astronomical cycles, (7) Inter-star gravitation, (8) Subtropical high of the West Pacific and (9) An anomalous field of sea temperature during previous winter. The effects of some of these physical factors on the super-huge flood along Yangtze River are strong, while that of the others are weak. For example, the effect of sunspot activity, the El Nino event and the strong earthquake in the south of the Qinghai-Tibetan Plateau on the super-huge flood along the Yangtze River is relatively strong and these are considered as strong signals, while the astronomical cycle and inter-star gravitation are regarded as weak signals. As they result in the super-huge flood along Yangtze River by causing large-scale anomalies of general circulation, sunspot activity, the El Nino event, a strong earthquake in the south of Qinghai-Tibetan Plateau and a solar eclipse may be classified as sun-air interaction, ocean-air interaction, land-air interaction and eclipse-air interaction respectively. The general research mainly focuses on the impact of single physical factors on the super-huge flood along Yangtze River in 1954. In fact, the super-huge flood along Yangtze River in 1954 is the superposition result of these factors, because compared to the other floods in the 20th century, the most physical factors appeared in 1954, with the strongest superposition effect and thus the grade of the super-huge flood along Yangtze River in 1954 is the greatest.

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