Monitoring of soil erosion in Cappadocia region (Selime-Aksaray-Turkey)     

H. M. Yilmaz  M. Yakar  O. Mutluoglu  M. M. Kavurmaci  K. Yurt 《Environmental Earth Sciences》2012,66(1):75-81

A fairy chimney is a conical rock formation, typically found in the Cappadocia region of Turkey. The geology of areas where fairy chimneys exist typically comprise a thick layer of tuff, covered by a thin layer of basalt or other volcanic rocks that are more resistant to erosion than the underlying tuff. Fairy chimneys are formed where a small cap or boulder of the original basalt remains, protecting a cone of tuff beneath it from erosion. Eventually, the tuff will be undercut to the extent that the cap falls off, and the remaining cone is then quickly eroded. In this study, the formation of fairy chimneys in the Cappadocia region was examined by investigating the surface soil erosion. A study area was selected and then scanned at five different times by a geodetic robotic total station at 40 cm horizontal and vertical intervals. The volumes of the study area were calculated from the same height and erosion was calculated from the volume differences indicated by the data. The relationship between erosion and meteorological data was analyzed, and showed that erosion had increased due to climatic conditions, particularly from the effect of rainfall.  相似文献   

Early Paleozoic Evolution of the NW Gondwanaland: Data from Southern Turkey and Surrounding Regions     

M. Cemal Goncuoglu  Huseyin Kozlu 《Gondwana Research》2000,3(3):315

The Lower Paleozoic rock-units in the Eastern Mediterranean can be separated into two distinct zones: the Northern Zone (Carpathian-Balkan, Istanbul, Zonguldak and Main Range terranes) and the Southern Zone (Tauride-Anatolide, SE Anatolian-Arabian, and Central Iranian terranes). A Gondwanan /Perigondwanan origin can only be properly indicated for the Southern Zone, whereas the Early Paleozoic paleogeographic positions of smaller terranes (e.g. Istanbul Terrane) of the Northern Zone remains questionable.During the Infracambrian-Early Cambrian time in the Southern Zone, the Pan-African consolidated NW Gondwanan pericratonic margin was rifted by back-arc extension or transtension, which is represented by the deposition of fault-controlled continental sediments.The late Early Cambrian-Late Cambrian period in the Southern Zone is designated by a regional transgression from northeast suggesting a rapid subsidence in the area to the northwest of Arabian-Tauride platform and hence opening of a relatively deep basin to the north.The Lower Ordovician in the Southern Zone comprising the Tremadoc and Arenig Series is characterized by a monotonous siliciclastic deposition. Towards the end of Early Ordovician shallowing upward sequences and formation of NW-SE trending highs were noticed. The stratigraphic hiatuses, unconformities and irregular distribution of the Caradoc-Ashgill deposits in the Southern Zone has been ascribed to glacio-eustatic sea-level changes.The Early Silurian (Aeronian-Telychian) deepening and deposition of black shales that follows the regression around the Ordovician-Silurian boundary in the Southern Zone is also very probably related to the relatively rapid global sea-level rise. To the north of the Tauride-Anatolide Platform, Wenlock and Late Silurian are represented by deep marine (basinal) sediments with oceanic basalts.The generation of an accretionary complex in the northern margin of the Taurides together with the regional regression in the southern Taurides and SE Anatolia at the uppermost Silurian-Lower Devonian boundary and the regional unconformity at Lower Devonian (Middle Lochkovian) is very probably related to the closure of a “Paleotethyan” oceanic basin to the north of the Perigondwanan terranes.  相似文献   

A small-scale landslide susceptibility assessment for the territory of Western Carpathians     

Juraj Holec  Martin Bednarik  Marián Šabo  Jozef Minár  Isik Yilmaz  Marián Marschalko 《Natural Hazards》2013,69(1):1081-1107

This study presented herein compares the bivariate and multivariate landslide susceptibility mapping methods and presents the landslide susceptibility map of the territory of Western Carpathians in small scale. This study also describes pioneer work for the territory of Western Carpathians, overreaching state borders, using verified sophisticated statistical methods. In the susceptibility mapping, digital elevation model was first constructed using a GIS software, and parameter maps affecting the slope stability such as geology, seismicity, precipitation, topographical elevation, slope angle, slope aspect and land cover were considered. In the last stage of the analyses, landslide susceptibility maps were produced using bivariate and multivariate analyses, and they were then compared by means of their validations. The validation of the bivariate analysis data was performed using the results of bivariate analysis for landslide areas of Slovakia containing five classes of susceptibility in scale 1:500,000. The validation area is the area of Western Carpathians within Slovakia. Eighty-two per cent of area does not differ in more than one class. The validation of the multivariate analysis data was performed using the results from the Kysuce region in the northern part of Slovakia in scale 1:10,000. The raster calculator was used to express the difference between each pair of pixels within these two layers. Seventy-seven per cent of the pixels do not differ in more than 25 %, 94 % of the pixels do not differ in more than 50 %. The maximal possible difference is 100 % (one pixel with value 0 and other with value 1, or vice versa). Receiver operating characteristic analysis was also performed, the area under curve value for bivariate model was calculated to be 0.735, while it was 0.823 for multivariate. The results of the validation can be considered as satisfactory.  相似文献   

A multi-technique approach to determine temporal and spatial variability of groundwater–stream water exchange     

Kasimcan Koruk  Koray K. Yilmaz  Zuhal Akyurek  Andrew Binley 《水文研究》2020,34(11):2612-2627

Characterizing the spatio-temporal distribution of groundwater–surface water (GW–SW) exchange fluxes is of paramount importance in understanding catchment behavior. A wide range of field-based techniques are available for such characterization. The objective of this study is to quantify the spatio-temporal distribution of the exchange fluxes along the Çakıt stream (Niğde, Turkey) through coupling a set of geophysical techniques and in-stream measurements in a hierarchical manner. First, geological and water quality information were combined at the catchment scale to determine key areas for reach-scale focus. Second, electromagnetic induction (EMI) surveys were conducted along the reach to pinpoint potential groundwater upwelling locations. EMI anomalies guided our focus to a 665 m-long reach of the stream. Along this selected reach, a fibre-optic distributed temperature sensing (FO-DTS) system was utilized to investigate streambed temperature profiles at fine spatial and temporal scales. Furthermore, vertical hydraulic gradients and exchange fluxes were investigated using nested piezometers and vertical temperature profiles, respectively, at two potential upwelling locations and a potential downwelling location identified by previous surveys. The results of the study reveal heterogeneity of vertical water-flow components with seasonal variability. The EMI survey was successful in identifying a localized groundwater upwelling location. FO-DTS measurements revealed a warm temperature anomaly during cold air temperature and low streamflow conditions at the same upwelling site. Our point-based methods, namely vertical temperature profiles and vertical hydraulic gradient estimates, however, did not always provide consistent results with each other and with EMI and FO-DTS measurements. This study, therefore, highlights the opportunities and challenges in incorporating multi-scale observations in a hierarchical manner in characterization of the GW–SW exchange processes that are known to be highly heterogeneous in time and space. Overall, a combination of different methods helps to overcome the limitations of each single method and increases confidence in the obtained results.  相似文献   

Improving WRF-Hydro runoff simulations of heavy floods through the sea surface temperature fields with higher spatio-temporal resolution     

Berina Mina Kilicarslan  Ismail Yucel  Heves Pilatin  Eren Duzenli  Mustafa Tugrul Yilmaz 《水文研究》2021,35(9):e14338

This study investigates the impact of the spatio-temporal accuracy of four different sea surface temperature (SST) datasets on the accuracy of the Weather Research and Forecasting (WRF)-Hydro system to simulate hydrological response during two catastrophic flood events over the Eastern Black Sea (EBS) and the Mediterranean (MED) regions of Turkey. Three time-variant and high spatial resolution external SST products (GHRSST, Medspiration and NCEP-SST) and one coarse-resolution and time-invariant SST product (ERA5- and GFS-SST for EBS and MED regions, respectively) already embedded in the initial and the boundary conditions datasets of WRF model are used in deriving near-surface atmospheric variables through WRF. After the proper event-based calibration is performed to the WRF-Hydro system using hourly and daily streamflow data in both regions, uncoupled model simulations for independent SST events are conducted to assess the impact of SST-triggered precipitation on simulated extreme runoff. Some localized and temporal differences in the occurrence of the flood events with respect to observations depending on the SST representation are noticeable. SST products represented with higher cross-correlations (GHRSST and Medspiration) revealed significant improvement in flood hydrographs for both regions. The GHRSST dataset shows a substantial improvement in NSE (~70%), RMSE reduction up to 20%, and an increase in correlation from 0.3 to 0.8 with respect to the invariable SST (ERA5) in simulated runoffs over the EBS region. The use of both GHRSST and Medspiration SST data characterized with high spatio-temporal correlation resulted in runoff simulations exactly matching the observed runoff peak of 300 m³/s by reducing the overestimation seen in invariable SST (GFS) in the MED region. Improved precipitation simulation skills of the WRF model with the detailed SST representation show that the hydrographs of GHRSST and Medspiration simulations show better performance compared to the simulated hydrographs by observed precipitation.  相似文献   

An alternative method for estimating densification point velocity based on back propagation artificial neural networks   总被引：1，自引：0，他引：1  

Mevlüt Güllü  İbrahim Yilmaz  Mustafa Yilmaz  Bayram Turgut 《Studia Geophysica et Geodaetica》2011,55(1):73-86

The establishment of Turkish National Fundamental GPS Network (TNFGN) was completed in 2001 and Large Scale Map and Map Information Production Regulation (LSMMIPR) came into force in 2005 in parallel with the establishment of TNFGN and the increase in the use of GPS applications. TNFGN has been designed as first order GPS network and it comprises second-, third- and fourth-order GPS densification networks. LSMMIPR has required determining the positions of first-, second- and third-order GPS densification (C1, C2 and C3) points with the reference epoch besides the measurement epoch. Therefore, it is necessary to estimate the velocity vectors of the densification points. In practise, the velocity vectors of C1, C2 and C3 points are estimated from TNFGN points or higher-order densification points velocity vectors by interpolation methods but LSMMIPR did not specify the interpolation method for this procedure. The objective of this study is to use a back propagation artificial neural network (BPANN) that has been more widely applied in engineering among all other neural network models for estimating the velocity of the densification point as an alternative to the interpolation methods. BPANN and selected ten interpolation methods are evaluated over a test area, in terms of root mean square error (RMSE). The results showed that the employment of BPANN estimated the densification point velocity (V_X,Y,Z) with a better accuracy (±5.0 mm, ±4.0 mm, ±3.9 mm, respectively) than the interpolation methods in the test area and indicated that BPANN can be a useful tool for estimating point velocity in the densification networks as a real alternative to the interpolation methods.  相似文献   

A view of tectonic structure and gravity anomalies of Hatay Region Southern Turkey using wavelet analysis     

Hakan Alp  A. Muhittin Albora Huseyin Tur 《Journal of Applied Geophysics》2011,75(3):498-505

In this study, we demonstrate wavelet analysis as a method of delineating the boundaries of subsurface geological structures. We applied wavelet transform to Bouguer anomaly data of the Cilicia Region and adjacent areas. The residual anomalies are the results of various depth and other properties of buried structures on the gravity anomaly map. The superposition of anomaly of the underground structures with different properties such as depth, density and size, increases the complexity of the overall system. Thus the extraction of the desired properties from the anomaly map becomes difficult. Different separation techniques are used to solve this problem. Wavelet transform is one of these modern approaches. Here, we tested various types of wavelet transform modeling on synthetic examples and then applied them to the gravity anomaly map of the Cilicia Region in Turkey. We have detected the borders of the Hatay Region in southern Turkey and proposed the tectonic model of this real complex structure using the wavelet transformation. The most important result we have found is the presence of a triple junction near the Hatay region.  相似文献   

Unique documentation,analysis of origin and development of an undrained depression in a subsidence basin caused by underground coal mining (Kozinec,Czech Republic)   总被引：1，自引：0，他引：1  

Marian Marschalko  Işık Yilmaz  David Lamich  Marián Drusa  Darja Kubečková  Tomáš Peňaz  Tereza Burkotová  Vladimír Slivka  Martin Bednárik  David Krčmář  Miloš Duraj  Alena Sochorková 《Environmental Earth Sciences》2014,72(1):11-20

This article aims to explain and demonstrate the origin and development of a subsidence basin caused by coal mining as well as to point out important aspects of this phenomenon in engineering geology. Engineering geology needs to deal with a number of issues related to the origin and development of subsidence basins in areas affected by deep coal mining. An interesting case study from the Upper-Silesian Basin in the northeast of the Czech Republic near the Polish border is presented in this paper. There is a clear time chronological succession in the ground surface changes manifested by a ground subsidence gradation, both in their absolute values as well as in their spatial distribution. The phenomenon is documented by aerial photo time series, which optimally depict the origin and development of the subsidence. In the study area, there are changes in the landscape elements and it is essential to be considered in future land use plans. The marginal conditions of the Quaternary geological structure and hydrogeological conditions are responsible for an unconfined aquifer which manifests there as a water body in an undrained depression in the course of the ground subsidence.  相似文献   

Determination of heavy metals in sediments of the Ergene River by BCR sequential extraction method     

Ali Sungur  Mustafa Soylak  Selehattin Yilmaz  Hasan Özcan 《Environmental Earth Sciences》2014,72(9):3293-3305

Utilizing the sequential extraction procedure (acid soluble, reducible, oxidizable, and residual) proposed by The European Community Bureau of Reference (BCR), the trace metals present in the sediments of the Ergene River, Turkey, were determined. The sediment samples were collected from 10 sampling sites and analyzed to identify the concentrations of cadmium, cobalt, chromium, copper, manganese, nickel, lead and zinc. The flame atomic absorption spectrometer was used for metal determination. The validation of the results was checked by the analysis of the BCR-701 standard reference material. The relationship existing between the sediment characteristics and metal fractions was identified using the correlation analysis. Hierarchical cluster analysis was performed to find out the grouping of the sampling sites based on the similarities of the heavy metals in the bioavailable fraction. When the extractable amounts of heavy metals are considered, the quantity of the mobile fractions (viz., acid soluble, reducible, and oxidizable) of the heavy metals is observed to be higher when compared with that of the immobile fraction (residual). This might be caused by the anthropogenic sources. Besides, it was statistically discovered that the organic matter, pH and clay contents could influence the bonding of the analyte metals in various forms. The cluster analysis revealed three clusters of the sampling stations, with group I (S5-8) and group II (S3, S4 and S9) showing higher environmental risks. The risk assessment code indicated that the highly mobile soluble fractions of Mn, Zn, Cd and Co created a high environmental risk which could result in negative impacts on the aquatic biota.  相似文献   

First Ground-Based Photometry and Light Curve Analysis of the Recently Discovered Contact Binary Hx Uma     

S. Selam  B. Albayrak  M. Yilmaz  H. V. Şenavci  İ Özavci  C. Çetintaş 《Astrophysics and Space Science》2005,296(1-4):305-308

Photoelectric UBV light curves of the recently discovered eclipsing binary HX UMa were obtained and studied to determine the preliminary physical parameters of the system for the first time. The observations were taken at the TüBİTAK¹ – Turkish National Observatory (TUG) on three nights in April 2003. A simultaneous analysis of the light and radial velocity curves yields a typical A-type contact binary with a high degree of overcontact. The influence of the close visual companion to the total light of the system was taken into account during the analysis. ¹TüBİTAK: The Scientific and Technical Research Council of Turkey.  相似文献