Browsing by Author "Bostan, Pinar"

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Assessing Variations in Climate Extremes Over Euphrates Basin, Turkey
(Springer Wien, 2020) Bostan, Pinar
The variation in climate extremes at different spatial and temporal scales can be conceived as an important indicator of climate change. The focus of this study is to reveal linear trends and observe space-time (ST) variation in extreme climate indices over the Euphrates Basin in Turkey. Extreme climate indices are calculated using daily maximum, minimum, and mean temperatures, including observations of daily precipitation measured from 41 meteorological stations from 1970 to 2017. Three precipitation indices, consecutive dry days (CDD), consecutive wet days (CWD), and precipitation intensity (SDII), together with three temperature indices, number of summer days (SU), number of frost days (FD), and growing season length (GSL), are analysed. Linear trends in these extreme indices are examined using the Mann-Kendall test. The ST distribution and variation in climate indices are examined through prediction maps for this study period. Ordinary kriging (OK), which has proven to be accurate and reliable in many studies, is used to obtain prediction maps on ST framework. Results indicated that there is an evident trend in the temperature-related indices. Regarding SU and GSL, about 66% and 34% of all stations, respectively, show a significant increasing trend. The downward trend (negativeZstatistic) for the FD is observed at approximately 83% of all meteorological stations, of which 35% show a significant trend. The ST variation in temperature-related extremes is evident from prediction maps; the trend is not as dominant for precipitation-related indices. In terms of ST prediction maps, the most prominent variation is observed in the south and northeast parts of the basin in CDD and CWD prediction maps from 2013 to 2017.
Simulating the Impact of Natural Disasters on Urban Development in a Sample of Earthquake
(Springer, 2023) Satir, Onur; Kemec, Serkan; Yeler, Okan; Akin, Anil; Bostan, Pinar; Mirici, Merve Ersoy
Natural disasters have been increased in areas, where people live densely, day by day. Istanbul 1999, Van 2011, and Izmir 2020 earthquakes were just some of the tragic events in the near past in Turkiye. The aim of this study was to define Van 2011 earthquakes effects as a sample on urban development by using land use/land cover projecting techniques. In this case, Van urban development (in urban macroform scale) was simulated without Van 2011 earthquakes based on existing urban development using the Cellular Automata Markov Chain (CA-MARKOV) approach for the year 2018. Effects of the earthquake were determined on urban development by comparing modeling results with observed 2018 built up areas. So that significant physical and social driving factors were evaluated including road distance, slope, hillshade, ground stability, and land use ability, and weighting values on urban development were calculated under the influence of the natural disaster. Van urban built up areas were mapped using high-spatial resolution remote sensing instruments such as SPOT, ASTER, RapidEye, and Gokturk 2 satellite dataset for 1988-2002-2011, and 2018 images applying an object-based classification approach (OBC). First of all, the model was validated using 1988, 2002, and 2011 urban development maps. The Kappa accuracy was found to be 0.85, respectively, for the model. Defined urbanization drivers were applied to the 2002-2011 time period to simulate 2018 urban areas without any earthquake. The results indicated that urban areas were affected by earthquakes. If there was no earthquake, urban development to the periphery would be 30% less. Additionally, 10% more built up areas would be constructed on ground sensitive areas, and only 2% of the new constructions would be established on suitable lands. Today this ratio is around 8%. As a result, urban development has been a trend to move from flat land to slight slopes and has been moved away from roads and settlements. It was determined that the spread into the city was accelerated as well as spread toward the periphery due to the earthquake.