Stability analysis and remedial measures of a landslip at Keifang,Mizoram – a case study

Landslips are often triggered due to non-engineered excavation of potential unstable slopes. Such slips can be stabilized by implementing suitable remedial measures.A landslip occurred at a drilling site of Oil India Limited in Mizoram State due to slope excavation. There was an immediate concern to protect the slope as the drilling platform and the highway at the top of the slope are at risk if further landslide occurs in future. Slope stability analysis of the failed slope was carried out to design suitable control measures for the protection of the slope from further sliding. Slope stability using various methods indicated that the slope is marginally stable. To improve the stability of the slope, suitable retaining structure at the toe of the slope was suggested and designed. Stability analysis performed with inclusion of retaining wall showed a significant increase in factor of safety of the slope. The suggested remedial measure has been implemented at the site and there is no landslip reported since then. The paper presents the results of the slope stability analysis and the design details of the retaining structure prescribed as the protection measure.     

Temporal–spatial variability of soil fertility in karst region: a case study of Xiaojiang watershed Yunnan

By sampling in the field and analyzing the soil samples in the laboratory in 1982 and 2005 the soil fertility data were obtained. Through application of geo-statistics combined with GIS, the temporal–spatial variability of the pH, organic matter, total nitrogen, total phosphorus and total potassium in soil of Xiaojiang watershed from 1982 to 2005 were analyzed. Results showed that: (1) the pH value and total potassium in soil showed an increasing trend, but the organic matter, total nitrogen and the total phosphorus in soil declined in the past 20 years in Xiaojiang watershed, (2) the parameters fitted by semivariogram models for fertility indices changed significantly in the past 20 years and (3) the result estimated by ordinary Kriging indicated the spatial pattern of the soil fertility indices changed significantly in the past 20 years. The soil pH increased in the east and southeast, but decreased in the middle of the watershed. The organic content of the soil matter decreased in the east, southeast and southwest, but increased in the northeast and middle of the watershed. The total nitrogen content of the soil decreased in the east, but increased in the middle of watershed. The total phosphorus content of the soil decreased in the whole watershed. The total potassium content of the soil increased in the southwest and southeast, but decreased in the middle of the watershed and (4) the change of land use and soil management measures was the main driving force of variability of soil properties.     

Statistical analysis of geo-electric imaging and geotechnical test results – a case study

For conjunctive use of geoelectric imaging and geotechnical site investigations in geotechnical characterization of major civil engineering construction sites, an objective assessment of influencing factors is important. Here, we present multiple regression analyses of both geoelectric (Electrical Resistivity Tomography, ERT; Induced Polarization Imaging, IPI) and geotechnical site investigations (Standard Penetration Test, SPT) for two profiles at a construction site for CGEWHO Complex in Greater Noida region, Delhi to assess the role of influencing formation factors like sand, fines and water content. Achieved results show that SPT ‘N’ and IPI are well predicted by a linear multiple regression. On an average, the nonlinear regression has improved predicted SPT ‘N’, resistivity and chargeability by 28.55%, 22.45% and 9.58%, respectively. The influence of sand and fines content is more than that of water content in the prediction of chargeability and SPT ‘N’. RMS error is less in prediction of IPI chargeability (average error of 1.96%) in comparison to SPT ‘N’ value (average error of 11.35%). As factors affecting chargeability (IPI) and SPT ‘N’ are similar, non-invasive IPI can be used along with few geotechnical site investigations for detailed geotechnical site investigations.     

Sedimentary processes,stratigraphic sequences and middens: the link between archaeology and geoheritage—a case study from the Quaternary of the Broome region,Western Australia

The cliffed and active dune coastal region of Broome provides an excellent record of Pleistocene and Holocene stratigraphy of desert environments interfacing with the Indian Ocean. The Mesozoic Broome Sandstone is the basal stratigraphic unit in the area and is overlain by Pleistocene red desert quartz sand (Mowanjum Sand). Modern coastal processes of waves, wind and tide have resulted in distinctive sedimentary bodies (stratigraphic units) clearly linked to the sedimentary environment. The Mowanjum Sand, reworked by coastal winds, generates the landward-ingressing orange quartzose Churchill Sand, or reworked by waves and abraded to white sand with the addition of carbonate grains that form the beaches (Cable Beach Sand) and with eolian action, coastal dunes or inland-ingressing white dunes (Shoonta Hill Sand). These sedimentary bodies and stratigraphic units form a template with which to locate and interpret archaeological middens and Indigenous occupation over the past 5000?years in a context of coastal occupation, coastal stability, mean sea-level changes, climate changes, and availability of marine food and freshwater. Shell middens and stone artefacts form definitive layers or horizons in relation to the stratigraphy, in places in situ, and elsewhere reworked as sheets and plumes; understanding their inter-relationships has enabled the unravelling of the archaeological history and relating Indigenous occupation to biofacies and lithofacies. The array of sedimentary, biofacies and stratigraphic units are of national geoheritage significance in their own right. The addition of archaeological deposits as stratigraphic units provides a link between geoheritage and archaeology, where the archaeological materials are viewed as part of the complex stratigraphic story, part of the coastal history, and part of the geoheritage story.     

Exploration and decision-making in geotechnical engineering – a case study

ABSTRACT

The paper presents methodologies for exploration planning under uncertain conditions based on virtual exploration and Bayesian updating. The process starts with site characterization using existing information to produce geologic profiles. Initial distributions of cost and time are obtained with a Bayesian network model that optimizes the construction strategy for particular geologic conditions. This is followed by the unique step to determine with a “virtual exploration” if additional exploration (e.g. borings) is warranted, and if so, where it should be best done. All this is then applied to the planned Abu Dhabi subway tunnels providing the transportation planners with necessary information for planning and design.     

The study of land desertification in transitional zones between the MU US Desert and the Loess Plateau using RS and GIS—a case study of the Yulin region

In this study, the land desertification of transitional zones of desert loess in the Yulin region (China) is studied from TM images in a geographical information system (GIS). It is found that the desertification in Yulin is still severe. The desertified land accounts for 67.7% of the total land areas. The distribution of desertified land shows obvious spatial imbalance, with severe desertification in northwestern regions and slight desertification in southeastern regions. This imbalance is related to the difference in physical factors and land-use pattern. The process of desertification in Yulin areas shows a steady and even reversed trend between 1987 and 1999, as a result of positive efforts. At the end of the paper the cause of desertification is discussed. It is believed that the interaction and confliction between the natural process and human activities may lead to the development of desertification.     

Hydrochemistry of groundwater in a coastal region and its repercussion on quality,a case study—Thoothukudi district,Tamil Nadu,India

A hydrogeochemical study was conducted in Thoothukudi district situated in the southeast coast of Tamil Nadu, India to identify the influence of saltwater intrusion and suitability of groundwater for domestic and agricultural purposes. Scattered studies of this coastal region have reported signs of seawater intrusion, salt pan and industrial activity together with natural weathering process. To have a holistic picture of geochemical processes in the entire district, a total of 135 groundwater samples were collected and analyzed for major cations and anions. The geochemical parameters were compared with world and Indian standards and it was found that most samples are unsuitable for drinking purpose. The geochemical facies of the groundwater showed Na–Cl as the dominant water type indicating the saline nature of the groundwater. Chadda’s plots show that most of the samples fall in the Na–Cl type of water due to seawater intrusion. The samples were classified with parameters like sodium absorption ratio, residual sodium carbonate, total hardness, chloride, index to base exchange, electrical conductivity and facies to determine their suitability for irrigation purpose. It was inferred that the samples falling along the coast are not suitable for the irrigation purpose. The seawater-mixing percentage indicates that strong mixing was observed in the near shore and at the proximity of the salt pan. The permanent hardness was predominant in all the samples compared to the carbonate hardness reducing its domestic usability.     

A numerical simulation of landslide-prone slope in Himalayan region—a case study

Stability of slope will always a problem due to its geodynamic nature of Himalayan region. The area investigated belongs to the Lower Siwalik formation, which is prone to failure due to presence of various weak planes or structures present in the rock mass. Frequent landslides causing loss of life, property, disturbance of morphological, surface and subsurface water flow pattern. A huge landslide in the Amiyan area occurred in 1999 and blocked the Gaula River which caused loss of agricultural land and other properties as well as waterlogged upstream side. The debris of Amiyan slope contains soil and sandstones of various types. This article deals with instability analysis of slopes of the Amiyan area, near Kathgodam, Nainital, Uttarakhand. This area experiences a number of local as well as regional slides. Extensive field surveys have been carried out to understand the geological detail. Laboratory experiments have been conducted to determine the various physicomechanical properties of rock mass. These properties have been used as input parameters for the numerical simulation. A number of researchers have used two-dimensional numerical models to simulate the slide area. Three-dimensional slope stability studies provide a better understanding of the mechanism of failure as well as zone of influence. The computed deformations and stress distribution, along the failure surface, have been compared with the field measurements and found to be in good agreement with field observations. In this case, finite difference method has been applied on the stability analysis of Amiyan slope. The study indicates that the slope is vulnerable and needs proper protection.     

Teaching GIS in the Gulf Co-operation Council Universities – With a case study of the geography department, University of the United Arab Emirates

Within universities there has developed a clear theoretical convergence between Geographical Information Systems (GIS) and geography (Antenuccl, 1991). Studies have revealed that one of the qualified departments to teach GIS within universities is the geography department. This study focuses on: the importance of establishing GIS as a major curriculum element within universities. In geography departments, economic geography students require a strong statistical/mathematical background to allow them to work with major databases. They should know how to design a specific database for economic activities, such as agriculture and manufacturing, and tertiary industry and how to relate this database to a map, so that changes can be monitored more accurately. In any aspect of geography spatial location is a key factor and GIS allows spatial patterns to be interpreted with great facility. Therefore it is important that students have a good knowledge not only of computers and related software on economic geography, but also on GIS systems (Burrough, 1993). The work of geography students from the United Arab Emirates (UAE) and other Gulf Co-operation Council (GCC) geography departments is examined to evaluate the importance of training in GIS technology. This paper evaluates the effects of implementing GIS as a tool in teaching economic geography. At present there are 15 geography departments in the GCC which offer economic geography. Of those 15 departments, only 3 provide GIS courses within their curriculum, and 4 have basic equipment, although 6 additional departments are to introduce GIS in the near future. This revised version was published online in July 2006 with corrections to the Cover Date.     

Probabilistic key block analysis of a mine ventilation shaft stability – a case study

In this study, the probabilistic key block analysis was applied to evaluate the stability of a mine ventilation shaft developed in a rock mass of granite. The key blocks were identified based on the block theory. The variations of discontinuity orientations were fitted with the Beta distribution and taken into consideration. The key block forming probabilities were analyzed. For simplification of calculations the first-order second-moment (FOSM) approximation was employed for probability estimation. With the considerations of the rock properties as random variables and applications of several statistical analysis tools, the key block failure probabilities, the probabilistic distribution of safety factors, and the probabilistic distribution of potential maximum key block volumes were analyzed. The analysis indicated that although the safety factor calculated based on the mean values of the variables was above 1.0 for the stability of the most critical key block, the block had a considerable probability of failure with a significant rock volume due to variations in discontinuity orientations and rock properties. Without promptly applying supports to the rock excavation, the shaft had a significant likelihood of failure.     

Assessing the vulnerability of social–environmental system from the perspective of hazard,sensitivity, and resilience: a case study of Beijing,China

Despite a recent increase in the number of vulnerability analyses there has been relatively little discussion of vulnerability assessment of social–environment system, especially when they face multiple hazards. In this study, we developed an applicable and convenient method to assess vulnerability of social–environment system at a regional scale. Vulnerability is quantified by measuring three critical elements (i.e. hazards, sensitivity, and resilience) through some key variables. The results showed that vulnerability is high in Miaofeng Mountain in Mengtougou District, the hills of Pinggu County and the riparian zones of the lower courses of the Beiyun and Yongding Rivers; but low in the city of Beijing and the southwestern part of the Fangshan District. Areas of very high, high, medium, and low-vulnerability account for 6.19, 25.48, 33.06, and 35.27% of the total area, respectively. The degree of vulnerability decreases in a northwest direction in mountainous areas and declines from watercourses to riparian zones along a lateral direction in the plain. Some adaptive strategies are also proposed.     

Integration of GIS and remote sensing for estimation of soil loss and prioritization of critical sub-catchments: a case study of Tapacurá catchment

Mapping of erosion risk areas is an important tool for the planning of natural resources management, allowing researchers to propose the modification of land use properly and implement more sustainable long-term management strategies. The objective of this study was to assess and identify critical sub-catchments for soil conservation management using the USLE, GIS, and remote sensing techniques. The Tapacurá catchment is one of the planning units for water resource management of the Recife Metropolitan Region. Maps of the erosivity (R), erodibility (K), slope (LS), cover-management (C), and support practice (P) factors were derived from the climate database, digital elevation model, and soil and land-use maps. In order to validate the simulation process, total sediment delivery ratio was estimated. The results showed a mean sediment delivery ratio (SDR) of around 11.5?% and a calculated mean sediment yield of 0.108?t?ha^?1?year^?1, which is close to the observed one, 0.169?t?ha^?1?year^?1. The obtained soil loss map could be considered as a useful tool for environmental monitoring and water resources management. The methodology applied showed acceptable precision and allowed the identification of the most susceptible areas to soil erosion by water, constituting an important predictive tool for soil and environmental management in this region, which is highly relevant for the prediction of varying development scenarios for Tapacurá catchment. This approach can be applied to other areas for simple and reliable identification of critical areas of soil erosion in catchments.     

Pseudo- and real-inverted metamorphism caused by the superposition and extrusion of a stack of nappes: a case study of the Southern Brasília Orogen,Brazil

International Journal of Earth Sciences - The Southern Brasília Orogen is a Neoproterozoic belt that occurs along the southernmost border of the São Francisco Craton where the...     

Geogenic distribution and baseline concentrations of Cu and Zn in surficial soil of Guiyang, China

1 IntroductionThe term“Environmental Geochemical Baseline(EGB)”first appeared in the International Geochemi-cal Mapping Program (IGCP259) and the InternationalGeochemical Baseline Program (IGCP360) of Interna-tional Geography Contrast Program. The defin…     

Growth of cyclone Viyaru and Phailin – a comparative study

The tropical cyclone Viyaru maintained a unique quasi-uniform intensity during its life span. Despite being in contact with sea surface for >120 hr travelling about 2150 km, the cyclonic storm (CS) intensity, once attained, did not intensify further, hitherto not exhibited by any other system over the Bay of Bengal. On the contrary, the cyclone Phailin over the Bay of Bengal intensified into very severe cyclonic storm (VSCS) within about 48 hr from its formation as depression. The system also experienced rapid intensification phase (intensity increased by 30 kts or more during subsequent 24 hours) during its life time and maximum intensity reached up to 115 kts. In this paper, a comparative study is carried out to explore the evolution of the various thermodynamical parameters and possible reasons for such converse features of the two cyclones. Analysis of thermodynamical parameters shows that the development of the lower tropospheric and upper tropospheric potential vorticity (PV) was low and quasi-static during the lifecycle of the cyclone Viyaru. For the cyclone Phailin, there was continuous development of the lower tropospheric and upper tropospheric PV, which attained a very high value during its lifecycle. Also there was poor and fluctuating diabatic heating in the middle and upper troposphere and cooling in the lower troposphere for Viyaru. On the contrary, the diabatic heating was positive from lower to upper troposphere with continuous development and increase up to 6^°C in the upper troposphere. The analyses of cross sections of diabatic heating, PV, and the 1000–500 hPa geopotential metre (gpm) thickness contours indicate that the cyclone Viyaru was vertically tilted (westward) and lacked axisymmetry in its structure and converse features (axisymmetric and vertical) that occurred for the cyclone Phailin. In addition, there was a penetration of dry air in the middle troposphere of Viyaru, whereas high moisture existed in the middle troposphere of Phailin. The vertical wind shear (5–10 ms^?1) near the core of the storm region between 850 and 200 hPa was favourable for both the systems but was higher in the northern region of the cyclone Viyaru. The divergent development of these thermodynamic features conspired to produce converse characteristic of the two cyclones.     

Failure risk assessment of interdependent infrastructures against earthquake,a Petri net approach: case study—power and water distribution networks

Metropolitan areas consist of complicated systems of interconnected infrastructures that are highly interdependent. Disruption of one infrastructure may induce disruption in other interconnected ones. The results from analysis of one infrastructure as an independent system are not realistic without considering the behavior of other interconnected infrastructures. Consequently, the study of the interdependencies among critical infrastructures is important for addressing the cascading effects of a failed infrastructure on the entire network to properly model its performance and help the disaster management team in decision making. In this study, the extended Petri net and Markov chain have been used to demonstrate the power and water infrastructure interdependency with a case study of one of the municipal districts of metropolitan Tehran, the capital of Iran. In this research, three cases have been assessed quantitatively: (1) the intra-dependency effects of different components in each network, (2) the interdependency effects between the considered critical infrastructures and (3) the behavior of the water network considering intra- and interdependency, when the power network fails. The analyses show that considering the mentioned interdependencies has a major influence on their performance simulations and assessment of their exact vulnerability. It is concluded that the failure probability of the water network that is dependent on the failed power network is 1.66 of the independent water network in the studied region. Eventually, the results of the research could be used in design, restoration and disaster management planning for safety assessment of critical infrastructures.     

Spatial–temporal differences in disaster perception and response among new media users and the influence factors: a case study of the Shouguang Flood in Shandong province

Natural Hazards - When human beings cannot avoid extreme climate disasters, it is widely accepted to take measures to address climate change. Research on ordinary people’s perception of...