Comparison of Planimetric and Thematic Accuracy of OrbView-3 and IKONOS Images     

Mustafa Yanalak  Elif Sertel  Nebiye Musaoglu  Cengizhan Ipbuker  Sinasi Kaya 《Journal of the Indian Society of Remote Sensing》2011,39(2):135-146

Spatial mapping from space using high-resolution satellite sensor data instead of conventional data collection techniques widely gained popularity. This study aims to analyze the planimetric and thematic accuracy of high-resolution OrbView-3 and IKONOS orthoimages. OrbView-3 and IKONOS images of a test area were acquired and these images were geometrically corrected using rational polynomial functions to conduct accuracy assessment. 40 Ground Control Points (GCPs) generated from static Global Positioning System (GPS) survey were used in the orthorectification procedure. 182 Test Points (TPs) produced from terrestrial surveying technique were used to analyze the accuracy of orthorectifications. Root Mean Square Error (RMSE) values obtained for GCPs and TPs were used to determine the planimetric accuracy of these images. Thematic accuracy analyses were conducted in radiometric and spatial base. Transects, lines and polygons were created to analyze the radiometric quality of data sets and to determine minimum distinguishable distance and distinguishable area. Both planimetric and thematic accuracy analyses illustrated that OrbView-3 and IKONOS images could be used to create 1:10000 scale map of the concerned region with appropriate planimetric and thematic quality.  相似文献   

Environmental implications of a hydrogeochemical survey for drinking water in Kirsehir region     

Yusuf Uras  Cagatayhan Bekir Ersu  Fevzi Oner 《Geochemistry International》2011,49(11):1145-1153

A hydrogeochemical survey of springs was carried out in Kirsehir, Turkey and fluoride, heavy metals, and mineral contents were analyzed. The highest fluoride levels were detected in Mahmutlu with 2.1 ppm. The fluoride content of Pohrenk was, on average, 1.1 ppm. Consequently, dental fluorosis and dental stains were observed in both villages. Although the fluoride concentrations were within the suggested limits, dental stains and fluorosis were commonly observed among the villagers especially kids. The fluoride concentrations of 0.7–1.0 ppm were the lowest in Cevirme, which is to the northwest of fluoride ore. The heavy metal concentrations of resources around the three villages were compared with and were found lower than WHO’s provisional guideline values. However, the Fe, Zn, and Cr concentrations in hot springs were much higher than cold springs with as much as 100 ppb for Fe, 50 ppb for Zn, and 15 ppb for Cr.  相似文献   

On the diet of Nile tilapia in two eutrophic tropical lakes containing toxin producing cyanobacteria     

Ronald Semyalo  Thomas RohrlackDuncan Kayiira  Yusuf S. Kizito  Stephen ByarujaliGeorge Nyakairu  Petter Larsson 《Limnologica》2011,41(1):30-36

Due to the production of toxins, cyanobacteria may adversely affect economically important fish such as Nile tilapia Oreochromis niloticus in tropical lakes. We studied the diet composition and factors affecting the diet of Nile tilapia in two tropical lakes where cyanotoxins were present. Particle-bound microcystins were present in all analysed water samples, ranging in concentration from 0.00012 to 1.11 and from 0.006 to 0.254 μg L⁻¹ in Murchison Bay in Lake Victoria and Lake Mburo, respectively. Detritus and phytoplankton were the main dietary components of the Nile tilapia, with phytoplankton contributing to over 30% by volume of stomach contents. The cyanobacteria Microcystis spp., which are also the most likely source of microcystins in the lakes, accounted for more than 80% of ingested phytoplankton. Microcystis spp. were also the most abundant cyanobacteria in both lakes (>60%). We found no significant relationship between the contribution of phytoplankton in Nile tilapia diet and the concentration of microcystins in the water but we found a close association between water transparency and the contribution of insects to Nile tilapia diets in Murchison Bay. Our results further show that none of the other measured environmental variables was a good predictor of diet items in Nile tilapia. Adult Nile tilapia in our study lakes, rely heavily on filter feeding, particularly under conditions of low water transparency, trapping detritus and phytoplankton cells especially colonies. They can ingest more mobile prey like insects and insect larvae when the water transparency and visibility increases.  相似文献   

Weak compositional zonation in a silicic magmatic system: Incesu ignimbrite,Central Anatolian Volcanic Province (Kayseri – Turkey)     

Tamer Koralay  Yusuf Kağan Kadioglu  Peter Davis 《Journal of Asian Earth Sciences》2011,40(1):371-393

The Central Anatolian Volcanic Province (CAVP), one of four major volcanic provinces in Turkey, plays a significant role in the interpretation of the tectonic evolution of Central Anatolia. The CAVP developed within a complex collisional system involving the African, Arabian and Eurasian plates during the Miocene. The volcanism exhibits complicated variations in mineralogical, petrological and geochemical compositions resulting from post-collisional lithospheric dynamics. The Incesu ignimbrite has 5–20 m thick and covers an area of ～7800 km². It is composed of three stratigraphic levels. The lower level (LL) shows blackish brown and glassy welded structure. The middle level (ML) is a well-welded, reddish pink in color and has large amounts of fiamme. The upper level (UL) is grayish pink, weakly welded and has rock fragments of different compositions. The Incesu ignimbrite is composed of plagioclase (oligoclase, andesine) + pyroxene (augite, clinoenstatite) + opaque minerals and low amount of amphibole, biotite and quartz. Eutaxitic texture is dominant in ML and LL samples; these levels are more strongly and contain more flattened pumice fragments and volcanic glass shards than in the UL. A sharp color contrast defines the contact between LL and ML.Major, trace and rare earth element of the Incesu ignimbrite, characterized by their rhyolite, rhyodacite–dacite composition, medium–high K, calcalkaline and peraluminous nature, show fractional crystallization primarily controlled by plagioclase, clinopyroxene, magnetite, ilmenite and titanomagnetite. Sr and Nd isotopic ratios of Incesu ignimbrite display isotopic variations between the ignimbrite levels; they exhibit a limited range in ⁸⁷Sr/⁸⁶Sr (0.7043–0.7049) and ¹⁴³Nd/¹⁴⁴Nd (0.512716–0.512760). The Sr–Nd isotopic ratio of Incesu ignimbrite reveals an age of 3 Ma. The ignimbrite evolved through fractional crystallization and crystal contamination of the parent magma derived from Ocean Island Basalt (OIB) like magma. This suggestion is supported by the AFC modeling based on the trace elements and Sr isotope data.Variation of several major oxide concentrations (Fe₂O₃, TiO₂, CaO and K₂O), trace element concetrations (V, Sr, Cs and Rb) and trace element ratios (Ba/Rb, Sr/, K/Sr, K/Nb, Rb/Sr, Rb/Y and Rb/Nb) versus SiO₂ concentration show the magma chamber that generated the Incesu ignimbrite was compositionally zoned. All geochemical and Sr–Nd isotpic datas can be interepreted to be the result of a subduction related source.  相似文献   

Performance of structures in the rural area during the March 8, 2010 Elazığ-Kovancılar earthquake     

Calayır  Yusuf  Sayın  Erkut  Yön  Burak 《Natural Hazards》2012,60(2):703-713

Numerous studies demonstrated the possibility of utilizing fly ash in the construction of embankments, road subgrades and stabilization of a wide range of soils. The present investigation aims at determining the optimum fly ash (OFA) for mechanical stabilization of expansive soils. Four different soils were tested for compaction characteristics and unconfined compressive strength with and without the addition of fly ash to determine the OFA. The liquid limit (LL) and the fraction coarser than 425 μ (CF) of these soils range from 50 to 120 and 25 to 70%, respectively. An experimental strategy called two-factor factorial design was adopted in the conducting experiments. LL and CF present in the soil are the two factors considered to influence the OFA content. Factorial experimentation enables relative quantification of the effect of each factor as well as their interaction with the OFA. The OFA was found to range from 5 to 40% depending upon the two factors. The LL and the CF were found to have dominating influence on OFA content in that order, whereas the interaction effect of these two factors was marginal to fair. A statistical regression model was developed for determination of the OFA in terms of the influencing factors. The validity of the model developed was verified by conducting laboratory tests on two more soils that were not used in the development of the model. Swell potential and swelling pressure of expansive soils were reduced to non-critical levels when treated with OFA.  相似文献   

Upper crustal electrical resistivity structures in the vicinity of the Çatalca Fault, Istanbul, Turkey by magnetotelluric data     

Gökhan Karcioğlu  Sabri Bülent Tank  Aysan Gürer  Elif Tolak Çiftçi  Tülay Kaya  Mustafa Kemal Tunçer 《Studia Geophysica et Geodaetica》2013,57(2):292-308

A magnetotelluric survey was performed at the Çatalca Region, west of Istanbul, Turkey with the aim of investigating geoelectrical properties of the upper crust near the Çatalca Fault and its vicinity. Broadband magnetotelluric data were collected at nine sites along a single southwest-northeast profile to image the electrical resistivity structure from surface to the 5 km depth. The dimensionality of the data was examined through tensor decompositions and highly two-dimensional behavior of the data is shown. Following the tensor decompositions, two-dimensional inversions were carried out where E-polarization, B-polarization and tipper data were utilized to construct electrical resistivity models. The results of the inversions suggest: a) the Çatalca Fault extends from surface to 5 km depth as a conductive zone dipping to southwest; b) the thickness of the sedimentary cover is increasing from SW to NE to 700 m with low resistivity values between 1–100 Ωm; c) the crystalline basement below the sedimentary unit is very resistive and varies between 2000–100000 Ωm; d) a SW-dipping resistivity boundary in the northeastern part of our profile may represent the West Black Sea Fault.  相似文献   

Advanced differential interferometry synthetic aperture radar techniques for deformation monitoring: a review on sensors and recent research development     

O. Idrees Mohammed  Vahideh Saeidi  Yusuf Ahmed Yusuf 《国际地球制图》2013,28(5):536-553

This paper reviews the advanced differential interferometry synthetic aperture radar (A-DInSAR) techniques, with two major components in focus. First is the basic concepts, synthetic aperture radar (SAR) data sources and the different algorithms documented in the literature, primarily focusing on persistent scatterers. In the second part, the techniques are compared in order to establish more linkage in terms of the variability of their applications, strength and validation of the interpreted results. Also, current issues in sensor and algorithm development are discussed. The study identified six existing A-DInSAR algorithms used for monitoring various deformation types. Generally, reports of their performance indicate that all the techniques are capable of measuring deformation phenomena at varying spatial resolution with high level of accuracy. However, their usability in suburban and vegetated areas yields poor results, compared to urbanized areas, due to inadequate permanent features that could provide sufficient coherent point targets. Meanwhile, there is continuous development in sensors and algorithms to expand the applicability domain of the technology for a wide range of deformable surfaces and displacement patterns with higher precision. On the sensor side, most of the latest SAR sensors employ longer wavelength (X and P bands) to increase the penetrating power of the signal and two other sensors (ALOS-2 PALSA-2 and SENTINEL-1) are scheduled to be launched in 2013. Researchers are investigating the possibility of using single-pass sensors with different look angles for SAR data collection. With these, it is expected that more data will be available for various applications. Algorithms such as corner reflector interferometry SAR, along track interferometry, liqui-InSAR, and squeeSAR are emerging to increase reliable estimation of deformation from different surfaces.  相似文献   

Ionization and dissociation equilibrium in strongly magnetized helium atmosphere     

Kaya Mori  Jeremy S. Heyl 《Monthly notices of the Royal Astronomical Society》2007,376(2):895-906

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Ethnic groups’ response to the 26 December 2004 earthquake and tsunami in Aceh, Indonesia   总被引：4，自引：4，他引：0  

Jean-Christophe Gaillard  Elsa Clavé  Océane Vibert  Azhari  Dedi  Jean-Charles Denain  Yusuf Efendi  Delphine Grancher  Catherine C. Liamzon  Desy Rosnita Sari  Ryo Setiawan 《Natural Hazards》2008,47(1):17-38

The 26 December 2004 earthquake and tsunami unfairly hit the different ethnic groups of Aceh, Indonesia. About 170,000 Acehnese and Minangkabau people died in the Northern tip of Sumatra while only 44 Simeulue people passed away in the neighbouring Simeulue island located near the earthquake epicentre. Such a difference in the death toll does not lie in the nature of the hazard but in different human behaviours and ethnic contexts. The present study draws on a contextual framework of analysis where people’s behaviour in the face of natural hazards is deeply influenced by the cultural, social, economic and political context. Questionnaire-based surveys among affected communities, key informant interviews and literature reviews show that the people of Simeulue detected the tsunami very early and then escaped to the mountains. On the other hand, Acehnese and Minangkabau people, respectively in the cities of Banda Aceh and Meulaboh, did not anticipate the phenomenon and were thus caught by the waves. The different behaviours of the victims have been commanded by the existence or the absence of a disaster subculture among affected communities as well as by their capacity to protect themselves in facing the tsunami. People’s behaviours and the capacity to protect oneself can be further tracked down to a deep tangle of intricate factors which include the armed conflict that has been affecting the province since the 1970s, the historical and cultural heritage and the national political economy system. This paper finally argues that the uneven impact of the 26 December 2004 earthquake and tsunami in Aceh lies in the different daily life conditions of the ethnic groups struck by the disaster.  相似文献   

A quantitative appraisal of earthquake hazard parameters computed from Gumbel I method for different regions in and around Turkey   总被引：2，自引：1，他引：1  

Serkan Öztürk  Yusuf Bayrak  Hakan Çınar  George Ch. Koravos  Theodoros M. Tsapanos 《Natural Hazards》2008,47(3):471-495

Useful information concerning the earthquake hazard parameters distributed in Turkey and the adjacent areas are estimated in the present work. Based on Gumbel’s I distribution parameters we are able to estimate the hazard values of the investigated area which are the mean return periods, the most probable maximum magnitude in the time period of t-years and the probability for an earthquake occurrence of magnitude ≥M during a time span of t-years. Figures concerning the spatial distribution of probabilities and the return periods are plotted and we considered them of particular interest for mapping the earthquake hazard in Turkey and the surrounding areas. These figures effectively produce a brief earthquake hazard atlas. The quantitative appraisal of the hazard parameters is useful for engineers, planners, etc., because it provides a tool for earthquake resistant design.  相似文献