International Journal of Environment and Geoinformatics

Number 2-2, 2015

1-15
Using Digital Elevation Model and Remotely Sensed Data in Determining the Geomorphological and Morphometric Features: Gaziköy-Saros Region, Northwestern Turkey

Authors: Şinasi KAYA, Okan TUYSUZ

Abstract

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Number of views: 340

The Gaziköy–Saros region is located in the western part of the North Anatolian Fault Zone (NAFZ), Turkey, which is one of the major active strike-slip faults recognized in the world. The morphological characteristics of this region were shaped by the nature of the fault. By means of combination techniques of remotely sensed and Digital Elevation Model (DEM) data a 3-D (three-dimensional) model can be generated. Afterwards, the produced 3-D model of the study region can be effectively used in examining the aforesaid features and various other associated analyses. In this study, the DEM data is obtained by digitizing 1/25,000 scaled maps and Landsat 5 TM data. A novel method is used to define the region’s geomorphology through merged digital elevation model (DEM) and remotely sensed data. The morphometric analyses of our study identified five erosion surfaces and indicated that the active faults contributed to the morphological development of the study area. Moreover, another hypothesis derived from our study is that the formation of the elevated areas was caused by fault compressional force components and formation’s linear features were produced by the strike-slips.

16-26
Connection between Ocean Acidification and Sound Propagation

Authors: Cem Gazioğlu , A. Edip Müftüoğlu , Volkan Demir , Abdullah Aksu, Volkan Okutan

Abstract

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Number of views: 495

Ocean Ambient Noise (OAN) results from both anthropogenic and natural sources. Varied noise sources are dominant in low (LFB: 10 to 500 Hz), medium (MFB: 500 Hz to 25 kHz) and high (HFB:>25 kHz) frequency bands. Mostly, LFB is dominated by anthropogenic sources. MFB that cannot spread over long ranges of sound sources contribute to the OAN. Ocean is an exceptionally noisy place. Ocean acidification (OAc) from rising Carbon dioxide (CO2 ) levels will result in decreased sound absorption and therefore, amplified levels of OAN. Carbon dioxide spewed into the atmosphere by burned fossil-fuel which dissolves in the seawater causes more acidic condition in oceans which has strong connection between chemical oceanography and sound propagation. As the ocean becomes more acidic, sound absorption at LFB decreases and acidic oceans would result in significant decreases in ocean sound absorption. In the recent years, the acoustic environment of oceans has reacted to transformations in both natural and anthropogenic impacts. Greenhouse gases concentrations, especially CO2 , rises in atmosphere due to industrial revolution. CO2 dissolved in the seawaters deposited in two major forms (carbonate and bicarbonate), which both lead to decrease pH of surface waters. Over the last 400 million years, pH of oceans has been stable around 8.2 globally. Latest investigations suggest that global pH is around 8.1 globally and various general oceanic circulation models (GOCM) calculate that, emissions could reduce ocean pH by a degree between 0.4 units (according to moderate approach) and 0.7 units (according to an aggressive one) by the end of this century. This article discusses the CO2 considerations both in the atmosphere and hydrosphere which are directly related with seawater pH and oceans noise levels.

27-38
Total Least Squares Registration of 3D Surfaces

Authors: Umut Aydar, M. Orhan Altan

Abstract

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Number of views: 335

Co-registration of point clouds of partially scanned objects is the first step of the 3D modeling workflow. The aim of co-registration is to merge the overlapping point clouds by estimating the spatial transformation parameters. In computer vision and photogrammetry domain one of the most popular methods is the ICP (Iterative Closest Point) algorithm and its variants. There exist the 3D Least Squares (LS) matching methods as well (Gruen and Akca, 2005). The co-registration methods commonly use the least squares (LS) estimation method in which the unknown transformation parameters of the (floating) search surface is functionally related to the observation of the (fixed) template surface. Here, the stochastic properties of the search surfaces are usually omitted. This omission is expected to be minor and does not disturb the solution vector significantly. However, the a posteriori covariance matrix will be affected by the neglected uncertainty of the function values of the search surface. . This causes deterioration in the realistic precision estimates. In order to overcome this limitation, we propose a method where the stochastic properties of both the observations and the parameters are considered under an errors-in-variables (EIV) model. The experiments have been carried out using diverse laser scanning data sets and the results of EIV with the ICP and the conventional LS matching methods have been compared.

39-45
The Problems and Solution Offers, Faced During The 3d Modeling Process Of Sekiliyurt Underground Shelters With Terrestrial Laser Scanning Method

Authors: Murat Yakar , Ali Ulvi, Ahmet Suat Toprak

Abstract

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Number of views: 269

The aim of this research is, to find out the practicality of using terrestrial laser scanners in the area of 3D modeling of underground cities and underground shelters and to offer a suggestion for possible problems. Our research concluded that the terrestrial laser scanners are suitable for mapping and modeling the underground shelters and cities and terrestrial laser scanning is a useful technique to obtain sensitive and detailed results for hastily scanned objects. Generated maps and measurements can be used as a base for future restoration and recreation works of the scanned objects.

46-55
Investigation of the Usability of Mobile Sensors for Weather Forecasting

Authors: Semih Dalğın and A. Özgür Doğru

Abstract

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Number of views: 295

Crowd sourcing is a popular method for providing data from people by the use of mobile sensor, internet and communication technologies. However efficient use of the raw data provided by the sensors with different characteristics in order to obtain accurate results is not investigated in detail. This study aims to investigate the data collected by mobile sensors integrated in the smartphones for scientific purposes such as weather forecasting. In this context, accuracy of the data provided mobile humidity, pressure and temperature sensors was examined in this study. Data provided by 5 smart phones and 3 Bluetooth sensors were tested in this context. Accuracy assessment process was performed by calculating the Root Mean Square Errors of the data with respect to reference data collected by TST Sensor simultaneously. This study shows that accuracy of the data collected with the mobile sensors is affected by several external parameters such as climatic conditions, handling habits of the user, and etc. Although it is possible to calculate correction constant for each sensor separately, it is not possible to calculate a unique and universal correction constant in order to increase the accuracy of the raw data collected by the mobile sensors. Therefore further studies should be executed for improving the accuracy of the mobile sensor data for scientific purposes

56-62
Experimental Investigation of Effects of Coastal Morphology on N-Waves

Authors: Taylan Bağcı, M. Sedat Kabdaşlı

Abstract

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Number of views: 281

A Leading Depression N-wave which consists of a negative and a positive amplitude solitary wave was generated with the help of a special designed wave pallet at Istanbul Technical University Hydraulic Laboratory. In addition, generated N-Wave was verified by using verification of related analytical equations. Furthermore, the wave flume was narrowed by narrowing angles of 5, 10 and 15 for analogy to morphology changes in coastal areas. It was determined that water level differences and phase shifts occurred to the narrowing effects.

63-76
High resolution mapping of urban areas using SPOT-5 images and ancillary data

Authors: Elif Sertel, Semih Sami Akay

Abstract

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Number of views: 357

This research aims to propose new rule sets to be used for object based classification of SPOT-5 images to accurately create detailed urban land cover/use maps. In addition to SPOT-5 satellite images, Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index (NDWI) maps, cadastral maps, Openstreet maps, road maps and Land Cover maps, were also integrated into classification to increase the accuracy of resulting maps. Gaziantep city, one of the highly populated cities of Turkey with different landscape patterns was selected as the study area. Different rule sets involving spectral, spatial and geometric characteristics were developed to be used for object based classification of 2.5 m resolution Spot-5 satellite images to automatically create urban map of the region. Twenty different land cover/use classes obtained from European Urban Atlas project were applied and an automatic classification approach was suggested for high resolution urban map creation and updating. Integration of different types of data into the classification decision tree increased the performance and accuracy of the suggested approach. The accuracy assessment results illustrated that with the usage of newly proposed rule set algorithms in object-based classification, urban areas represented with seventeen different sub-classes could be mapped with 94 % or higher overall accuracy.

77-87
New Observations of Alien Foraminifera on the Turkish Coasts of the Aegean Sea (2008-2011)

Authors: Engin Meriç , M. Baki Yokeş , Niyazi Avşar , Feyza Dinçer

Abstract

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Number of views: 264

Invasion of the Mediterranean Sea by alien species is an ongoing process. Each year new alien species are being recorded in the Levantine basin. To date, 37 alien foraminifer species are known to inhabit Turkish coastline. Because of low water temperature it is hard ot survive for the thermophilic alien species in the Aegean Sea. Until 2008, only 12 alien foraminifers have been reported from the Aegean coasts, however the recent studies increasd this number to 31. The reports of İridia diaphana Heron-Allen and Earland, Quinqueloculina sp. C, Triloculina affinis d’Orbigny, Triloculina sp. A, Euthymonacha polita (Chapman), Coscinospira acicularis (Batsch), Polymorphina fistulosa Cushman and Brizalina simpsoni (Heron-Allen ve Earland) constitutes first records. Besides, Haddonia sp., Nodopthalmidium antillarum (Cushman), Spiroloculina antillarum d’Orbigny, Hauerina diversa Cushman, Triloculina fichteliana d’Orbigny, Peneroplis arietinus (Batsch), Sorites variabilis Lacroix, Cymbaloporetta plana (Cushman), C. squammosa (d’Orbigny), Amphistegina lessonii d’Orbigny are first records for the Turkish Aegean fauna.

88-105
Assessment of Stability and Energy Dissipation Performances of an Antifer Layer Protected Caisson

Authors: Dursun Zafer Şeker, M. Sedat Kabdaşlı , Murat Çelikoyan, Cem Gazioğlu

Abstract

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Number of views: 314

The present study intends to assess the stability and energy dissipation performances of a breakwater configuration (APC) protected by an antifer layer. For comparison, an ordinary caisson (OC), which was 5% wider and 10% heavier, was also investigated. Physical models were implemented and tested under regular and irregular waves; and resulting linear and angular displacements were directly measured via a photogrammetric method. Additionally, wave forces and resulting horizontal displacements were estimated both from recorded pressure data and from individual incident waves by modified Goda method. To calculate the horizontal displacement, the estimated wave force time series were directly double-integrated, whilst the theoretical method proposed by Shimosako et al. (1994) were used on the individual force values. Although OC was tested under shorter durations and had a more favorable superstructure in terms of resisting forces, the results indicated that APC was significantly more stable. Energy dissipation performance of the tested configurations were quantified in terms of spectral averaged and phase resolved reflection coefficients, whereas antifer damage ratio was measured on a block-count basis. Results indicated that the APC configuration had an enhanced performance of dissipating the wave energy; moreover, the dissipated energy directly links to antifer damage ratio.