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Kivanc Zorlu M. Celal Tunusluoglu Tolga Gorum Hakan A. Nefeslioglu Ali Yalcin Dilek Turer Candan Gokceoglu 《Environmental Earth Sciences》2011,62(8):1685-1693
The Cappadocia region has unique geomorphological features resulting from differential erosional processes which make it very attractive to tourists. Besides the fairy chimneys for which the area is best known, there are also impressive buttes and mesas. Buttes and mesas are formed in regions having flat-lying strata in which the uppermost levels are composed of well-cemented limestones and granular ignimbrites, whereas the lower parts and slopes consist of low-durability tuff and ignimbrites. This durability difference results in serious rockfall events. This study involves two-dimensional rockfall analyses in and near the Avanos, Zelve, and Çavusini areas, where volcano-sedimentary units of Neogene age outcrop, to provide a rockfall hazard map in which areas of tourism activity are also considered. 相似文献
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Working in complex grounds have always been difficult for engineering geologists because of the heterogenous nature of such
geo-materials, which results in different behaviors under stresses. The caliches outcropping in the Adana basin and its close
vicinity are selected as the study material because of their highly complex nature and also understanding their mechanical
behaviour and collapse potential is too difficult, although their aerial extent is large in the region. For this reason, investigation
of the collapse potential and mechanical behaviour of the caliches by applying new approaches besides the conventional in
situ and laboratory tests is the purpose of the study. The study includes five main stages such as measurements of caliche
profiles, in situ tests (plate loading), sampling, shooting photographs for photoanalyses and laboratory studies. Four different
levels such as hard pan; silty, sandy layer; gravelly, blocky layer and clayey level are described for the caliches employed.
The hard pan level is a weak rock with an average uniaxial compressive strength of 11.89 MPa while the others have typical
soil characteristics. A series of plate loading tests are applied on the blocky, gravelly level of the caliche to determine
the modulus of elasticity. The modulus of elasticity and the allowable bearing capacity are determined between 28.6–65.3 and
1.5–2.0 MPa, respectively. To determine the grain size distribution curve, in addition to sieve analyses, a photoanalysis
technique is also applied and a combination procedure between the results from both sieve analyses and photoanalyses is introduced
and the grain size curves for the blocky, gravelly level of the caliche are obtained. According to the results of collapse
potential index tests performed on the samples collected from 20 locations of the study area, the soft pan level of the caliche
has slight to moderate degree of collapse indices. In the final stage, various simple and statistically meaningful empirical
equations are proposed for the indirect determination of the collapse index by employing simple paramateres. 相似文献
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This article presents results of mercury in surface waters from Hunza River basin, Northern Areas, Pakistan. Small‐scale gold mining activities along the Hunza and Gilgit rivers are long known to be discharging mercury in the amalgamation and roasting processes. Previous studies reported high mercury concentrations in soils close to mining operations as well as serious health problems for miners. However, none of the studies have focused on the level of contamination in aqueous environments. This is the first study on the investigation of source and fate of sediment and river‐borne mercury in the Hunza River. The samples collected near gold panning sites showed higher mercury concentrations than critical levels established by the U.S. Environmental Protection Agency. The observed dissolved mercury concentrations ranged from 5.10 to 25.25 ng/l, whereas particulate‐bound mercury ranged from 4.85 to 154.62 ng/l. Particulate‐phase mercury corresponded to more than 75% of the total observed mercury concentrations for all of the sampled rivers. Thus, suspended sediments represented the major pathway of the riverine mercury transport. A mass balance calculation suggested an annual mercury flux of 48.6 g/km2 into the Hunza River basin. The samples collected from the most affected river, the Shimsal River, averaged to have 108 ng/l total mercury. This amount was close to the average soil mercury data of 151 ng/l as reported by the Pakistan Mineral Development Corporation in 2001. The dominant source of contamination was shown to be the leaching of large quantities of mercury from the mercury‐rich sediment and flood plain soil into the rivers, rather than the direct release from mining activities. Significant decrease in both dissolved and particulate‐bound mercury concentration downstream of Attabad Lake suggested that mercury is being accumulated or consumed in the lake. Although minimization or elimination of mercury loses from the mining process seems important for the well‐being of the miners, preventing the remobilization of accumulated mercury is equally important in mercury control in this region. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Prediction of uniaxial compressive strength of sandstones using petrography-based models 总被引：2，自引：0，他引：2
K. Zorlu C. Gokceoglu F. Ocakoglu H.A. Nefeslioglu S. Acikalin 《Engineering Geology》2008,96(3-4):141-158
The uniaxial compressive strength of intact rock is the main parameter used in almost all engineering projects. The uniaxial compressive strength test requires high quality core samples of regular geometry. The standard cores cannot always be extracted from weak, highly fractured, thinly bedded, foliated and/or block-in-matrix rocks. For this reason, the simple prediction models become attractive for engineering geologists. Although, the sandstone is one of the most abundant rock type, a general prediction model for the uniaxial compressive strength of sandstones does not exist in the literature. The main purposes of the study are to investigate the relationships between strength and petrographical properties of sandstones, to construct a database as large as possible, to perform a logical parameter selection routine, to discuss the key petrographical parameters governing the uniaxial compressive strength of sandstones and to develop a general prediction model for the uniaxial compressive strength of sandstones. During the analyses, a total of 138 cases including uniaxial compressive strength and petrographic properties were employed. Independent variables for the multiple prediction model were selected as quartz content, packing density and concavo–convex type grain contact. Using these independent variables, two different prediction models such as multiple regression and ANN were developed. Also, a routine for the selection of the best prediction model was proposed in the study. The constructed models were checked by using various prediction performance indices. Consequently, it is possible to say that the constructed models can be used for practical purposes. 相似文献
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Kivanc Ertugay Sebnem Duzgun 《International journal of geographical information science》2013,27(9):1491-1506
The term physical accessibility has long been used by geographers, economists, and urban planners and reflects the relative ease of access to/from several urban/rural services by considering the traveling costs. Numerous accessibility measures, ranging from simple to sophisticated, can be observed in the geographical information systems (GIS)-based accessibility modeling literature. However, these measures are generally calculated from a constant catchment boundary (a most likely or average catchment boundary) based on constant deterministic transportation costs. This is one of the fundamental shortcomings of the current GIS-based accessibility modeling and creates uncertainty about the accuracy and reliability of the accessibility measures, especially when highly variable speeds in road segments are considered. The development of a new stochastic approach by using global positioning system (GPS)-based floating car data and Monte Carlo simulation (MCS) technique could enable handling the variations in transportation costs in a probabilistic manner and help to consider all possible catchment boundaries, instead of one average catchment boundary, in accessibility modeling process. Therefore, this article proposes a stochastic methodology for GIS-based accessibility modeling by using GPS-based floating car data and MCS technique. The proposed methodology is illustrated with a case study on medical emergency service accessibility in Eskisehir, Turkey. Moreover, deterministic and stochastic accessibility models are compared to demonstrate the differences between the models. The proposed model could provide better decision support for the decision-makers who are supposed to deal with accessibility, location/allocation, and service/catchment area related issues. 相似文献
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Martin Sahlén Pedro T. P. Viana rew R. Liddle A. Kathy Romer Michael Davidson Mark Hosmer Ed Lloyd-Davies Kivanc Sabirli Chris A. Collins Peter E. Freeman Matt Hilton Ben Hoyle Scott T. Kay Robert G. Mann Nicola Mehrtens Christopher J. Miller Robert C. Nichol S. Adam Stanford Michael J. West † 《Monthly notices of the Royal Astronomical Society》2009,397(2):577-607
We forecast the constraints on the values of σ8 , Ωm and cluster scaling-relation parameters which we expect to obtain from the XMM Cluster Survey (XCS). We assume a flat Λ cold dark matter Universe and perform a Monte Carlo Markov Chain analysis of the evolution of the number density of galaxy clusters that takes into account a detailed simulated selection function. Comparing our current observed number of clusters shows good agreement with predictions. We determine the expected degradation of the constraints as a result of self-calibrating the luminosity–temperature relation (with scatter), including temperature measurement errors, and relying on photometric methods for the estimation of galaxy cluster redshifts. We examine the effects of systematic errors in scaling relation and measurement error assumptions. Using only ( T , z ) self-calibration, we expect to measure Ωm to ±0.03 (and ΩΛ to the same accuracy assuming flatness), and σ8 to ±0.05, also constraining the normalization and slope of the luminosity–temperature relation to ±6 and ±13 per cent (at 1σ), respectively, in the process. Self-calibration fails to jointly constrain the scatter and redshift evolution of the luminosity–temperature relation significantly. Additional archival and/or follow-up data will improve on this. We do not expect measurement errors or imperfect knowledge of their distribution to degrade constraints significantly. Scaling-relation systematics can easily lead to cosmological constraints 2σ or more away from the fiducial model. Our treatment is the first exact treatment to this level of detail, and introduces a new 'smoothed ML' (Maximum Likelihood) estimate of expected constraints. 相似文献
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The Plio-Quaternary conglomeratic sets within the marine environment of the Viranşehir coast (W Mersin, S Turkey) are responsible
for the evolution of sandy and gravely beaches due to their control on various factors such as sea floor irregularity, wave
energy, and organic activity. The conglomeratic sets close to the shoreline (50–150 cm) act as wave breakers, creating hard
substratum and high energy, well-oxygenated environment for organisms like Patella sp., Phoronida worms and Brachidontes pharaonis (Fischer P. 1870). The boring activities of these organisms have disintegrated the sandy matrix of these sets. Finer-grained
matrix sediments have been transported to the interset and open sea, while cobble–pebbles have been carried landwards and
have created imbricated gravely beach deposits without matrix. Sandy beach is evolving where the conglomeratic sets away from
the shoreline (5.0–10.0 m). In this example, sets form a bar; causing fivefold division as backshore, berm, surf zone, bar
and offshore from land to sea. Poorly sorted, cobbles-pebbles cobbles and pebbles are found associated with the high-energy
environments of bars, whilst well-sorted sands are observed in low energetic environments on shore. The sets and recent shell
fragments are the main sources of coastal sediments in Viranşehir. However, the amount of shell fragments decrease towards
the active river mouth. This is due to sediment and fresh water influx from the river causing deteriorated temperature, salinity
and light penetration of the marine environment resulting in less organic diversity.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
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The Zonguldak province is a coastal settlement area that has been suffering from serious natural and human-induced environmental
problems sourced by its geology and geomorphology. Since the province locates at the heart of a coal-producing basin, the
geo-environmental problems related to mining activities such as esthetic degradation, disposal of mining wastes and subsidence
of the abandoned coal galleries are badly affecting every day life in Zonguldak province. Disposal of municipal wastes is
also a big problem since only one municipality out of 32 has a sanitary disposal area. The rest of the municipalities dispose
their solid wastes to rivers or to the sea. The province has also some health problems, which are pointed out in the literature,
related to coal mining and geologic environment. These are cytogenetic damage in peripheral lymphocytes and pheumoconiosis
(most commonly seen at coal workers), goiter and cancer. Landslides are the most important hazards in the area since 13% of
the total surface of the Zonguldak is affected by landslides. In this study, considering the hazard potential special attention
is given to deep landslides and using the stepwise forward conditional logistic regression technique, the landslide susceptibility
map for the Zonguldak province is produced. The results showed that the most important independent variables governing the
landslides are slope gradient, volcanic, and sedimentary rocks of Eocene and clastic and carbonate units of Cretaceous. The
landslide map is used as a base map for the production of geo-hazard reconnaissance map on which areas subjected to other
important geo-hazards (flood, earthquake and subsidence) are also shown to provide guidance for both existing settlement areas
to take the necessary preventive measures and for new developing settlement areas to avoid the problematic areas. 相似文献
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