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51.
In earthquake prediction studies, the regional behaviour of accurate 222Rn measurements at a set of sites plays a significant role. Here, measurements are obtained using active and passive radon detector systems in an earthquake-active region of Turkey. Two new methods are proposed to explain the spatial behaviours and the statistical uncertainties in the 222Rn emission measurements along fault lines in relation to earthquake occurrence. The absolute point cumulative semivariogram (APCSV) and perturbation method (PM) help to depict the spatial distribution patterns of 222Rn in addition to the joint effects of the K dr, the radon distribution coefficient, and the perturbation radon distribution coefficient (PRDC). The K dr coefficient assists in identifying the spatial distributional behaviour in 222Rn concentrations and their migration along the Earth’s surface layers. The PRDC considers not only the arithmetic averages but also the variances (or standard deviations) and the correlation coefficients, in addition to the size of the error among the 222Rn measurements. The applications of these methodologies are performed for 13,000 222Rn measurements that are deemed to be sufficient for the characterization of tectonics in the Keban Reservoir along the East Anatolian Fault System (EAFS) in Turkey. The results are evaluated for the ?çme earthquake (M L 5.4, 5.7 km, 23 June 2011), which occurred in the vicinity of the EAFS. 相似文献
52.
Habip Eroğlu Günay Çakır Fatih Sivrikaya Abdullah E. Akay 《Stochastic Environmental Research and Risk Assessment (SERRA)》2010,24(5):699-704
Soil erosion is one of the most important environmental problems. In the case of small scale areas where soil properties and
climate have relatively uniform characteristics, vegetation cover and topography (i.e. ground slope) are the main factors
that affect the amount of soil erosion. Lack of vegetation cover on bare soil areas, including forest road side slopes, especially
in mountainous regions with steep slopes, may significantly increase the erosion rate. Determining and classifying erosion
risks in such areas can help preventing environmental impacts. In this study, remotely sensed data and elevation data were
used to extract and classify bare soil erosion risk areas for a study area selected from Hatila Valley Natural Protected Area
in northeastern Turkey. High resolution IKONOS imagery was used to apply land use classification in ERDAS Imagine 9.0. To
generate erosion risk map of the bare soil areas, classified image was superimposed on top of slope map, generated based on
a Digital Elevation Model (DEM) in ArcGIS 9.2. The results indicated that 1.43, 5.85, 34.62, 53.16, and 4.94% of the bare
soil areas in the study area were under very low, low, medium, high, and very high erosion risks, respectively. The overall
classification accuracy of 82.5% indicated the potential of the proposed methodology. 相似文献
53.
Fatih Ünes 《洁净——土壤、空气、水》2010,38(3):296-308
Experimental findings and observations indicate that plunging flow is related to the formation of bed load deposition in dam reservoirs. The sediment delta begins to form in the plunging region where the inflow river water meets the ambient reservoir water. Correct estimation of dam reservoir flow, plunging point, and plunging depth is crucial for dam reservoir sedimentation and water quality issues. In this study, artificial neural network (ANN), multi‐linear regression (MLR), and two‐dimensional hydrodynamic model approaches are used for modeling the plunging point and depth. A multi layer perceptron (MLP) is used as the ANN structure. A two‐dimensional model is adapted to simulate density plunging flow through a reservoir with a sloping bottom. In the model, nonlinear and unsteady continuity, momentum, energy, and k–ε turbulence equations are formulated in the Cartesian coordinates. Density flow parameters such as velocity, plunging points, and plunging depths are determined from the simulation and model results, and these are compared with previous experimental and model works. The results show that the ANN model forecasts are much closer to the experimental data than the MLR and mathematical model forecasts. 相似文献
54.
Natural Hazards - On January 24, 2020, a severe earthquake of magnitude Mw 6.8 hit the Sivrice district of Elaz?? province at 20:55 (17:55 GMT) local time. This earthquake caused... 相似文献
55.
Digital elevation model(DEM) is the most popular product for three-dimensional(3D) digital representation of bare Earth surface and can be produced by many techniques with different characteristics and ground sampling distances(GSD). Space-borne optical and synthetic aperture radar(SAR) imaging are two of the most preferred and modern techniques for DEM generation. Using them, global DEMs that cover almost entire Earth are produced with low cost and time saving processing. In this study, we aimed to assess the Satellite pour l'observation de la Terre-5(SPOT-5), High Resolution Stereoscopic(HRS), the Advanced Space-borne Thermal Emission and Reflection Radiometer(ASTER), and the Shuttle Radar Topography Mission(SRTM) C-band global DEMs, produced with space-borne optical and SAR imaging. For the assessment, a reference DEM derived from 1∶1000 scaled digital photogrammetric maps was used. The study is performed in 100 km2 study area in Istanbul including various land classes such as open land, forest, built-up land, scrub and rough terrain obtained from Landsat data. The analyses were realized considering three vertical accuracy types as fundamental, supplemental, and consolidated, defined by national digital elevation program(NDEP) of USA. The results showed that, vertical accuracy of SRTM C-band DEM is better than optical models in all three accuracy types despite having the largest grid spacing. The result of SPOT-5 HRS DEM is very close by SRTM and superior in comparison with ASTER models. 相似文献
56.
Ferhat Ozcep Engin Erol Fatih Saraçoğlu Mustafa Haliloğlu 《Environmental Earth Sciences》2012,66(6):1617-1630
Slope failures triggered by earthquakes are among the most important soil mechanics problems. In this study, static and pseudostatic analyses of slope stability for earthquake conditions were carried out in the Gurpinar area. In situ testing (SPT) was carried out and laboratory samples were obtained from six boreholes (maximum depth 50.0 m) to determine soil classification and strength characteristics. Geophysical studies (seismic refraction and MASW) were also carried out in the area to estimate the structure and stiffness strength characteristics of the slope to 50.0 m depth. All field and laboratory data were used to determine the mechanical and structural (geometrical) behavior of the slope. In order to solve the slope stability problem, three soil slope models were considered. Pseudostatic analysis was carried out to estimate the earthquake acceleration seismic hazard in the region. These analyses showed that, while there was no potential slope instability under static load conditions, some problems would appear with increasing earthquake acceleration. A geotechnical slope improvement project is proposed for the study area. 相似文献
57.
Geotechnical assessments of the stability of slopes at the Cakmakkaya and Damar open pit mines (Turkey): a case study 总被引：2，自引：2，他引：0
Fehmi Arikan Fatih Yoleri Sureyya Sezer Dincer Caglan Bengu Biliyul 《Environmental Earth Sciences》2010,61(4):741-755
The on-site observations, monitoring data, and results of back analyses of failures showed that large-scale failures occurred
along both the interconnected sliding surfaces, consisting of (a) discontinuities in the dacites and the contact zone and
(b) the circular surfaces through the weathered soil-like dacites at the Cakmakkaya and Damar open pit mines. Surface water
infiltration through the weathered soil-like material after a short duration of rainfall contributed to the circular-shaped
failures. After a heavy rainy period, an increase in the groundwater table above the contact zone played a major role in the
initiation of bi-planar wedge failures. In addition, the stability of the slopes is likely to have been controlled by the
orientation of this zone. The results of back analyses indicated that the shear strengths of the soil-like materials in the
weathered dacites and the contact zone had reduced to their residual values at the time of initial sliding. The flattening
of the slope angles with an effective surface drainage and long-term monitoring of the groundwater level is proposed as the
most suitable remedial measure. 相似文献