Sinasi Kaya

Use of Semivariograms to Identify Earthquake Damage in an Urban Area

The 1999 Izmit earthquake (Mw 7.4) on the North Anatolian Fault Zone resulted in severe damage to the urban areas of Izmit, Adapazari (Sakarya), Golcuk, and Yalova. A semivariogram approach was used to quantify earthquake-induced spatial variation and thereby the degree of damage in the Adapazari inner city. Semivariograms were calculated for 24 transects on SPOT high resolution visible infrared (HRVIR) panchromatic images obtained before and after the earthquake. The differences between the pre- and postearthquake semivariogram shape and measures of shape, range, nugget, and sill were related to the severity of earthquake damage

Geometric correction accuracy of different satellite sensor images: application of figure condition

In this study, the figure condition method was introduced to analyse the accuracy of geometric correction. Figure condition denotes the transformation ability of estimated model parameters for a given transformation model, and it can be used in a geometric correction procedure. To study the figure condition, multisensor satellite images were geometrically corrected using ground control points obtained by different methods. The accuracy of each geometric model was analysed by means of the root mean square error of unit weight and variance–covariance matrix of unknown parameters. Then, an error propagation law was applied to the geometric model in order to investigate the transformation ability of the model parameters and estimate error values of geometric correction for the whole image surface. The results of the research demonstrated that the figure condition can be applied to geometric correction, and error values of the whole study area can be obtained with this new approach without using check points.

Post‐earthquake building collapse: a comparison of government statistics and estimates derived from SPOT HRVIR data

On 17 August 1999 at 3:02 a.m. local time the Izmit earthquake occurred on the North Anatolian Fault Zone (NAFZ) in north‐west Turkey. This earthquake caused considerable damage in the urban areas of Izmit, Adapazari (Sakarya), Golcuk and Yalova. This study used three different data sources to estimate the proportion of Adapazari that contained collapsed buildings: (i) government statistics on the number of collapsed buildings; (ii) the difference between pre‐ and post‐earthquake land cover estimated from classified SPOT HRVIR XI images; and (iii) land cover estimated from density‐sliced SPOT HRVIR Panchromatic image recorded after the earthquake. The results were similar at 16%, 16.1% and 15.5%, respectively. These were all slight overestimates; however, the remotely sensed estimates provided the spatial context of building collapse and in doing so highlighted areas of previously uncontrolled building.

Multi-Temporal Analysis and Mapping of Coastal Erosion Caused by Open-Mining Areas

Coastal zones are exposed to erosion due to natural and human-induced activities around the world. The land use of the coastal zone in the northern part of Istanbul, Turkey, has been changing due to open-pit coal mining begun in 1980. The objective of this study is to determine the changes that occurred in a selected coastal zone by utilizing interpretations of multi-temporal LANDSAT satellite data. Satellite images of the zone taken during the years 1984, 1992, and 2001 were transformed to the universal transverse mercator (UTM) coordinate system, and 17 bands of images for each of these years were interpreted using layer-stack method. A new red, green, and blue (RGB) image including infrared band of each year was created. These findings show that 304.7 ha area of sea was filled with soil between years 1984 and 1992. However, the total area filled between 1984 and 2001 was only 67.7 ha, due to the fact that 237.0 ha was removed by coastal erosion after year 1992.

The use of geostatistical methods to identify severe earthquake damage in an urban area

Izmit earthquake (Mw 7.4) occurred on the north Anatolian Fault Zone (NAFZ) in the northwest of Turkey on 17 August 1999 and resulted in severe damage to the urban areas of Izmit, Adapazari (Sakarya), Golcuk and Yalova. A semi-variogram approach was used to quantify earthquake-induced spatial variation and as a result, identify severely damaged regions in Adapazari inner city. The inner city of Adapazari was divided into twelve 1 km times 1 km blocks. Omnidirectional semi-variograms of these blocks were calculated using SPOT HRVIR Panchromatic images obtained before and after the earthquake. The differences between the pre and post earthquake semi-variograms were correlated with the location of severely damaged areas. These differences were determined for the range, nugget and sill of the semi-variograms and an independently produced damage map was related to the results of this semi-variogram analysis.

Analysis of land cover/use changes using Landsat 5 TM data and indices

Urban expansion and unprecedented rural to urban transition, along with a huge population growth, are major driving forces altering land cover/use in metropolitan areas. Many of the land cover classes such as farmlands, wetlands, forests, and bare soils have been transformed during the past years into human settlements. Identification of the city growth trends and the impact of it on the vegetation cover of an area is essential for a better understanding of the sustainability of urban development processes, both planned and unplanned. Analyzing the causes and consequences of land use dynamics helps local government, urban planners, and managers for the betterment of future plans and minimizing the negative effects.This study determined temporal changes in vegetation cover and built-up area in Istanbul (Turkey) using the normalized difference vegetation index (NDVI), soil-adjusted vegetation index (SAVI), and built-up area index (BUAI). The temporal data were based on Landsat 5 Thematic Mapper (TM) images acquired in June of 1984, 2002, 2007, 2009, and 2011. The NDVI was applied to all the Landsat images, and the resulting NDVI images were overlaid to generate an NDVI layer stack image. The same procedure was repeated using the SAVI and BUAI images. The layer stack images revealed those areas that had changed in terms of the different indices over the years. To determine temporal change trends, the values of 150 randomly selected control points were extracted from the same locations in the NDVI, SAVI, and BUAI layer stack images. The results obtained from these control points showed that vegetation cover decreased considerably because of a remarkable increase in the built-up area.

Spatial Analyses for Environmental Impacts of Landfill Areas

This study presents significant spatial and temporal aspects of solid waste management on a case study conducted at the Istanbul Metropolitan area, where existing models of waste management have significant limitations due to limitations of handling spatiality and temporality. Since the decision making process should be performed over time and across space, remote sensing technology provides mature solutions. In order to analyze the changes IRS 1C PAN (5×5 m spatial resolution and dated 2000) and the IKONOS MS (4×4 m spatial resolution and dated 2004) images have been used. For the landfill areas, Istanbul Metropolitan area currently involves two sites, 1/5000 scaled map and both satellite images were overlaid in order to visualize the differences between reserved area and used area of the landfill. In order to analyze the flow direction of landfill areas towards watershed areas a Digital Elevation Model (DEM) was constituted and analyses were performed. The spatial and temporal changes of the two landfill areas were detected and results were discussed.