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  • Öge
    Potential implications of sea-level rise in Türkiye and its vicinity
    (Graduate School, 2022-10-08) Alabay, Ebru ; Karaca, Mehmet ; Baykara, Metin ; 601201007 ; Earth System Sciences
    In the last century, the sea-level rise has accelerated due to anthropogenic climate change. With the growing population, the consequences of climate change have become more adverse. As in the rest of the world, the population pressure is high on the Turkish Coasts, where 45 million people live in. Türkiye, which has a long shoreline with 8333 km covered with seas on three sides will be affected adversely by the consequences of accelerated sea-level rise (e.g. flooding, salt intrusion, erosion, etc.). In addition to physical hazards, also socio-economic losses will have consequences. The purpose of this study is to determine the potential implications of the sea-level rise on Turkish coasts. For this purpose, the monthly sea-level data in the Turkish Seas (the Black Sea, the Marmara Sea, the Aegean Sea, and the Mediterranean Sea) are received from the Permanent Service for Mean Sea Level. However, some tide gauge stations have data gaps and insufficient data for determining long-term sea-level change. Therefore, cubic interpolation was applied to eliminate the data gaps, also the tide gauge station data in the same sea are combined to create a longer time series of sea-level change. Thus, the mean sea-level rise rates in the Black Sea, the Marmara, the Aegean, and the Mediterranean Sea are calculated at 5,31 mm/yr in 1874-2018, 8,79 mm/yr in 1984-2009, 0,844 mm/yr in 1969-2019, 0,8455mm/yr in 1923-2019, respectively. It is determined that sea-level rise has accelerated in recent decades. The accelerated sea-level rise causes the increasing frequency and intensity of disaster floods, inundations, coastal erosion, landslides, saltwater intrusion, and even storm surges. The main economic activities in this region are tourism, agriculture, fishing, port, and industry sectors. In Turkey, the coastal low-lying delta areas (i.e. Cukurova, Bafra, Carsamba, Meric, Goksu, etc.) are important in agricultural production. Especially one-third of Samsun is covered with agricultural lands its agricultural contribution to the economy is approximately $1 billion. Thanks to their long sandy beaches, the Mediterranean and the Aegean are among the destinations that attract a lot of international tourists and play an important role in the development of the region locally and nationally. Another popular destination for international tourists is Istanbul with its natural beauty, rich culture, and historical places. Hence, the socio-economic factors on the Turkish coast were examined. The contribution of the coastal region is estimated at two-thirds of the Turkish Gross Domestic Product (GDP): the Marmara, the Aegean, the Mediterranean, and the Black Sea coastal regions' contributions are 44.5%, 8.3%, 8.4%, and %4.7 respectively. As a result, these economically active regions are essential to be protected against sea-level rise. In this study, adaptation strategies have been determined for the protection of coastal areas from the destructive consequences of sea-level rise. In addition, the adaptation costs for agricultural areas (Bafra and Carsamba) in Samsun, and the sandy beaches are also examined.
  • Öge
    Ecological niche modeling of Myotis davidii
    (Graduate School, 2022-06-09) Aksakal, Emre Can ; Çoraman, Emrah ; 601181012 ; Earth System Science
    Myotis davidii is a whiskered bat species distributed in large areas of the Western Palaearctic. It has a cryptic sister species, Myotis mystacinus, which also has a similar distribution range in Europe and western Asia. The distribution of M. davidii extends from the Balkans to the Far East Asia, whereas M. mystacinus is found in Europe, Anatolia, and the Caucasus. They have a sympatric range in an area extending from the Balkans to the Transcaucasia via Anatolia. In this sympatric area, the populations of M. davidii had discordant patterns of mitochondrial and nuclear DNA, indicating that there were gene exchange between these species in the past. In this study, it was aimed to investigate the effects of the past climatic conditions on the evolutionary history of M. davidii and its cryptic sister species, M. mystacinus. The particular aims of this thesis are: 1) to construct the bioclimatic niches of M. davidii and M. mystacinus; 2) to identify their putative refugial areas during the last glacial period; and 3) to assess their responses to current climate change. In order to investigate these aims, ecological niche models were utilized. Ecological niche models aims to predict the distribution range of species by matching the environmental factors with species occurence points. Ecological niche modeling approach has become a common and practical application in conservation and biogeography study, especially with the advent of computer sciences and essential databases. In this study, ecological niche models are constructed by using the R programming language, as implemented in the BIOMOD2 package. A maximum entrophy appoach was used, which is a machine learning method developed for ecological niche modelling applications. The constructed models captured the current range of M. davidii but failed for M. mystacinus. For Myotis mystacinus, the lack of data from the Balkans and Anatolia was the likely reason for the unsuccessful model projections. The models for M. davidii suggest that inaccordance with the genetic lineages there might be to separate ecological units. Past projections suggest that Anatolia and the Balkans might have acted as refugial areas for both of the species during the Last Glacial Maximum. For M. davidii, the coastal regions of the Black Sea and the Mediterranean regions of Anatolia were likely refugial areas. These findings highlights the importance of Anatolia as a glacial refugium. Finally, the future projections suggested that there will major range shifts in the distribution of these species, especially for M. mystacinus moving towards norther Europe.
  • Öge
    The impact of climate change on future extreme precipitation in Turkey
    (Graduate School, 2021-08-06) Albayrak, Derya ; Şen, Ömer Lütfi ; 601191005 ; Earth System Science ; Yer Sistem Bilimi
    This study investigates the impact of climate change on extreme precipitation in Turkey with the aid of both historical and model-based future projection data. Firstly, we have applied the equidistant quantile matching method and generated bias-adjusted extreme precipitation daily and sub-daily time series of 73 stations in Turkey from a 14 member CMIP6 ensemble. The resulting data are utilized for deriving the Intensity-Duration-Frequency curves for two future periods (2020-2050 and 2070-2100) and results are spatially presented. Thus, annual extreme precipitation with 1-hr, 2-hr, 6-hr, 12-hr, and 24-hr durations over Turkey are examined for 10-yr, 25-yr, 50-yr, and 100-yr return periods in two future periods through a CMIP6 ensemble-based analysis. The impacts of climate change on annual extreme precipitation in the regions of Turkey are estimated. Our CMIP6-ensemble analyses reveal that for the reference period 1970-2000 the highest impacts over Turkey are estimated for shorter duration (≤ 6-hr) generally higher-frequent annual extreme precipitation which may be attributed to the thermal enhancement due to the mean temperature increase in Turkey. Moreover, for all durations and frequencies covered here, till the mid-century, change in regional medians varies between 4.6-10.4% in the Marmara region, 4.9-8.4% in south-eastern Anatolia, 7.4-10.4% in the Aegean region, -1.8-0.8% in central Anatolia, 6.8-12.1% in eastern Anatolia, 5.2-7.2% in Black Sea region, 4-14.2% in Mediterranean region. Due to the high spatial variability of the extreme precipitation, both decreasing and increasing relative changes occur in the regions. However, by the end-century, the impact of annual extreme precipitation in the regions noticeably intensifies, relative regional medians raise to 18.5-21.7% in Marmara region, 14.8-18.7% in south-eastern Anatolia, 10.2-13.9% in Aegean region, 13.4-16.6% in central Anatolia, 19.3-23.3% in eastern Anatolia, 16.2-20.7% in Black Sea region, 15.1-21.1% in Mediterranean region. Coastal regimes in Turkey receive a higher amount of annual extreme precipitation than the continental parts, especially local extremes that are noticeable on the coastal line, which is projected for all future periods and extreme precipitation durations presented in this study. Moreover, according to the median of the relative changes among the regions, the south and north coasts of Turkey are subject to the impact of different annual extreme precipitation durations. Northern coastal regimes are projected to have the highest impact by the intensification of the short-duration annual extremes (≤ 2-hr annual extreme precipitation). Southern coastal regimes are estimated to have the highest impact by the longer duration (≥ 6-hr) annual extreme precipitation events. Central Anatolia, the only region with persistent decreasing median changes till the mid-century, experiences a substantial increase in the impact of the 1-hr and 2-hr high-frequent convective precipitation extremes at the end-century. Crucial for adaptation and mitigation strategies, our current practice of deriving and implementing Intensity-Duration-Frequency curves rely on the historical data, which may be insufficient for capturing the variable impacts of climate change. Consequently, underestimating the impact of climate change on extreme precipitation may result in a decrease in the capacity of the numerous hydrological systems to deliver the required services at their optimum. Thus, decision and policymakers should evaluate and consider the intensification of different extreme precipitation durations among both the regions and the future periods to eliminate the exacerbated vulnerability of the hydrological systems to climate change-related extreme precipitation events and manage adverse socio-economic consequences.