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Öğe Changes and trends in total yearly precipitation of the Antalya district, Turkey(ELSEVIER SCIENCE BV, 2014) Altin, Turkan Bayer; Barak, Belma; Efe, R; Ozturk, M; Atalay, IIn this study, long term changes and trends in the annual rainfall of the Antalya Part, which is the region located in the western Mediterranean coast of Turkey containing many agricultural areas in its surrounding, were analysed. The aim of this study was to analyse the long term changes and trends in rainfall totals and present spatial distributions of annual and seasonal rainfall variability over the part. Rainfall data from 7 meteorological stations (Antalya, Alanya, Manavgat, Gazipasa, Finike, Korkuteli and Elmali) covering the years 1970-2011 were used in this study. Prepared rainfall variation maps clearly show that the highest annual variation is Antalya, while the lowest variation is Manavgat. According to the results obtained in trend analysis, in general, while a decreasing trend in winter rainfall is apparent, there is an apparent increasing trend in autumn rainfall. These results show a shift in seasons causing long-term droughts and potential infertile land to emerge. At some stations in the vicinity, there has been a prominent change from humid conditions to semi-arid conditions from beginning of 2000s. This study is expected to contribute to better understanding the effects of global climate change over precipitation in Antalya vicinity. (C) 2013 The Authors. Published by Elsevier Ltd.Öğe Determination of drought intensity in Seyhan and Ceyhan River Basins, Turkey, by hydrological drought analysis(Springer Wien, 2020) Altin, Turkan Bayer; Saris, Faize; Altin, Bekir NecatiThis paper studied hydrological drought identified by the Streamflow Drought Index (SDI) at eight river-gauging stations in the Eastern Mediterranean part of Turkey for a roughly 43-year period covering from 1972 to 2014 (4 stations), from 1973 to 2015 (2 stations), and from 1969 to 2011 (2 stations). Results of SDI analyses indicate that the number of drought years was highest during the 3-month October-December period. A considerable part of the drought years was determined to be mild drought. Although moderate drought conditions were observed in all stations, moderate drought conditions were determined especially at Goksu-H in the Seyhan River Basin and Sogutlu and Savrun in the Ceyhan River Basin. Short-term fluctuations of dry and wet conditions are the dominant pattern for most of the stations; however, long-term persistent drought conditions are also prominent, especially at Tacin and Korkun in Seyhan Basin and Goksun in Ceyhan Basin. The starting point for the negative trend in the 12-month series was the years 1996, 1999, and 2000.Öğe Development and morphometry of drainage network in volcanic terrain, Central Anatolia, Turkey(ELSEVIER SCIENCE BV, 2011) Altin, Turkan Bayer; Altin, Bekir NecatiThis paper presents the results of morphotectonic and morphometric research carried out in order to determine the neotectonic development of the volcanic mountains and a drainage network in SW Cappadocia. The study area extends among the Aksaray, Nigde, and Nevsehir Provinces. The study area comprises Hasandag, Melendiz, Keciboyduran, Golludag Mountains and the adjacent parts of these volcanic mountains. Data collected exclusively from 1:25,000 digitised topographic maps and 10 m-resolution DEMs were used to define parameters related to the longitudinal profile of streams. The study area was divided into 10 volcanic units. Longitudinal profiles of 20 streams and stream orders were analysed to determine a regional tectonic differentiation pattern in these units. The streams in the study area drain into four different tectonic depressions. These depressions are Aksaray plain controlled by the Tuz Golu fault (TCF), Ciftlik plain controlled by the Keciboyduran Melendiz fault (KMF), Misli plain controlled by the Derinkuyu fault (DF), and Bor plain controlled by the Nigde Fault Zone (NFZ). An analysis of morphometric parameters shows that the development of a drainage network is associated with faults and rock resistance. Occurrence of morphometric parameters with different values in units reveals that the volcanic mountains were not uplifted in the same period and were subjected to different morphologic processes. High total order number in the south of Hasandag (unit 3) and Melendiz Mountains (unit 7) indicate that the uplift ratio of the southern part is much greater than that of the northern part. Moreover, development of the drainage network in the south is in a more advanced phase than in the north. Indeed, the drainage network in the north is in the youngest erosional phase of all parts of the study area. The increased stream length-gradient indices (SL), and stream gradients and an analysis of headward erosion show that the streams displaying the longest and highest reach of the erosional phase are all in the southern part of Keciboyduran and Melendiz Mountains. The longitudinal profile (Lp) of the present thalweg of the streams is irregular. The irregular Lp are associated with four different causes. These are geological variations in resistance, tectonics, and volcanic topography and downcutting in response to stream incision. The beginning of the fluvial incision in the northern part is younger than in the south. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.Öğe Drainage morphometry and its influence on landforms in volcanic terrain, Central Anatolia, Turkey(ELSEVIER SCIENCE BV, 2011) Altin, Turkan Bayer; Altin, Bekir Necati; Efe, R; Ozturk, MAn evaluation of morphometric parameters was made to study drainage morphometry and its influence on landform processes, flood and erosion characteristic in subbasins which are located in volcanic terrain between Nigde and Aksaray Province SW Cappadocia, Central Anatolia. The study area was divided into 28 subbasins. The high flood potentiality exists on the high volcanic cones, dom, dissected foot of mountains and the high parts of plateaus covering the 13 subbasins, and are associated with high slope, shape of subbasins, impermeable geology and sparce vegetation. The moderate flood potentiality exists on the plateaus covering the 9 subbasins and is associated with high drainage density, high stream frequency, high bifurcation ratio and high slope conditions; although these subbasins have long narrow shapes. The low flood potentiality exists on plains covering 5 subbasins and is associated with low slopes and its long narrow shape. Analysis of drainage morphometry helps to understand interrelationships between landforms and flood potentiality for planning and management in basins. (C) 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of The 2nd International Geography Symposium-Mediterranean EnvironmentÖğe Environmental and climatic changes during the Pleistocene-Holocene in the Bor Plain, Central Anatolia, Turkey(ELSEVIER SCIENCE BV, 2015) Altin, Turkan Bayer; El Ouahabi, Meriam; Fagel, NathalieThe Bor Plain lies in a round-shaped flat basin in the southern part of the Central Anatolia. It is located at the southeastern end of the Tuzgolu Fault Zone which is the NW trending, active normal fault zone and extends between the north of the Tuzgolu (Lake Tuz) at NW and at Kemerhisar (Nigde) SE. According to geomorphologic and geologic studies, this plain was occupied by lake during the Pleistocene. The first high lake level (terrace) and the latest high lake level (terrace) were determined at 1170-1150 m and 1110-1100 m, respectively. Pleistocene and Holocene alluvial and lacustrine deposits are composed of claystone, sandstone, mudstone, limestone and paleosol units. These units contain mostly calcite and clay minerals (palygorskite, smectites, illite and chlorite), and lesser amounts of quartz, phillipsite, cristobalite, feldspar, plagioclase, goethite and, muscovite. The results of this study are compared with the results of sedimentologic and dating obtained from Konya-Eregli Plain. According to this comparison, 1 the latest high lake terraces were dated 23,000 to 17,000 yr BP. The high lake level was changed, 2 sandy level with carbonate determined in stratigraphy indicates that a dry phase dominated after 17,000 yr BP, and 3 black and brown muds indicate that the shallow freshwater lacustrine phases and sandy levels were formed between 12,500 and 1100 yr BP during late glacial stage. Paleosols, muddy levels and shallow lake deposits were formed in the environment of the Holocene during 6000-5000 yr BP. Carbonate-rich sandstone and mudstone deposits show that this period was interrupted by the second drought in the latest stage. Temperatures have increased due to hot climate conditions and salinization has begun and been still ongoing. (C) 2015 Elsevier B.V. All rights reserved.Öğe Evaluation of Drainage in the Upper Catchment of the Yesilirmak River Basin Along the Alm us Fault, Northern Turkey(Istanbul Univ, Fac Letters, Dept Geography, 2020) Altin, Turkan Bayer; Altin, Bekir NecatiThe Yesilirmak River Basin is located in the North Anatolian Fault Zone (NAFZ) which is one of the fault zones with intense seismic activity in Turkey. The Almus Fault is a segment of the North Anatolian Fault (NAF). This study aims to reveal the effect of the Almus Fault on the drainage development and morphotectonic evolution of the upper catchment of the Yesilirmak River Basin and the relative tectonic activity of the fault. Morphometric indices such as, stream length gradient index (SL), mountain front sinuosity (Smf) and fan entrenchment (E) indicate that the downward of the sub-basins is tectonically more active than the upward which is ascribed to the tectonic activities along the Almus Fault. The Smf value is 1.4 at the west and decreases to 1.1 at the mouth of the sub-basins on the east. This indicates that the tectonic activity along the Almus fault in the study area increases from west to east and the uplift rate in the northern part is higher than the southern part of the study area. Development of the drainage network started during Pliocene due to differential uplift and a humid climate then developed under tectonic forcing during Quaternary.Öğe Geomorphic Signatures of Active Tectonic in Drainage Basins in the Southern Bolkar Mountain, Turkey(SPRINGER, 2012) Altin, Turkan BayerBolkar Mountain forms the northeast extent of the Central Taurus Mountains, which are located north of the eastern Mediterranean Sea and consist of 3000 m or higher summits. The study area southern part of Bolkar Mt, has been investigated for geomorphic signatures of active tectonics using Geographical information system (GIS). The lower valley floor-to-width to height and elongation ratios, higher convexity, stream length-gradient (SL) indices, hypsometric integral and convex nature of the hypsometric curves and topographic asymmetry show that relative tectonic activity is greater in the eastern sector affected by Ecemis fault. Spatial variations of tectonic activity along rivers studied point to a general trend of decreasing activity towards the west as well as tectonic activity again increase in the west. Westward migration of basin and range extension is consistent with the place of uplift in the southern Bolkar Mt. Topography of the southern sector is the result of Late Miocene-Early Pliocene extension related uplift. Drainage systems in the upper part of the central and western sectors are under the lithological control and karstic denudation; whereas the development of the drainage systems in the middle and outlet parts of all sectors depend on sea level changes and Late Quaternary tectonism. The development of drainage systems of the eastern sector depends mostly on fault tectonism and climatic changes in the Late Quaternary.Öğe Landslide-Triggering Factors in Korucak Subbasin, North Anatolian, Turkey(ELSEVIER SCIENCE BV, 2015) Altin, Turkan Bayer; Gokkaya, Ergin; Drusa, M; Marschalko, M; Yilmaz, I; Segallini, A; Ferrero, AM; Bednarik, MKorucak Creek Basin is located within upper course of the Yesilirmak River Basin and southern Middle Karadeniz (Black Sea) section which is known to have the potential of landslide and flood risk. The purpose of identification of landslide-triggering factors is to highlight the regional distribution of potentially unstable slopes and to guide decision makers for regional planning purposes. We assessed morphometric parameters for landslide-triggering factors of Korucak Creek Basin using GIS (Geographical Information System). These parameters are Stream Power Index (SPI) and Compound Topographic Index (CTI). Moreover, slope and elevation values of the basin were classified and superposed over the geologic map. Landslide locations were identified from topographic maps and verified with field observation. The total catchment area of the basin is about 55 km2. More than half of the total basin is covered by metamorphic rock types such as schist, which has high permeability and weakness against erosion and is one of the main causes of the landslides. The results show that the main triggering factors are slope and lithology. Thus, northern and western of the Korucak subbasin are under the highest-risk landslide areas. (C) 2015 The Authors. Published by Elsevier B.V.Öğe The flood risk of the Yesilirmak basin (upper course), Turkey(ELSEVIER SCIENCE BV, 2014) Altin, Turkan Bayer; Efe, R; Ozturk, M; Atalay, IThis paper presents the flood potential of the sub-basins, which are located in upper course of the Yesilirmak River, Tokat Province. This potential was determined by analysing shape indices which have been used for several decades to describe the characteristics and hydrological properties of drainage basins. These indices are Form Factor, Basin Elongation, compactness, circularity Ratio, Lemniscate ratio and shape index. Drainage networks for sub-basins were prepared with a topographic map scaled 1/25000 and 10-m resolution DEM using GIS. The study area was divided into six sub-basins. The shape indices show that six sub-basins have an elongated shape causing low-magnitude peak flood. In spite of a moderate amount of rainfall and elongated shapes, the main problem of this area is that it has been subjected to flood since 1950. The results indicate that the steep slopes, impermeable lithology and thick vegetation accelerate the flow of rainfall. In other words, flood events are also formed in an elongated basin. This result will help in better understanding relationships between the flood events and basin shape for basin area planning and management. (C) 2013 The Authors. Published by Elsevier Ltd.Öğe The Holocene terraces of the desiccated Bor Lake and Neolithic occupation in Bor Plain, Central Anatolia, Turkey(Springer, 2021) Altin, Turkan Bayer; Kayseri-Ozer, Mine Sezgul; Altin, Bekir NecatiThe lacustrine sediments and geomorphological data from the Bor Plain situated at elevations between 1050 and 1100 m in southern Central Anatolia provide record between 9800 and 6700 yr cal BP of climate changes and events. The main aim of this study is to determine the relationship between the location of Neolithic sites and the deposition and recession phases of the lake during Holocene. The geomorphological history of the Bor Plain and palynological results allows us to reconstruct the relationship between the Holocene environment and reconstruction of Neolithic settlements within a spatially well-defined lacustrine landscape of similar to 600 km(2). A 75 +/- 13 ka aged terrace, consisting almost entirely of calcite and situated about 76 m above the plain floor, indicates that the plain was covered with a paleolake in the transition from MIS 5 to MIS 4. Considering the low total organic carbon and the high CaCO3 clay values, we conclude that the lake slowly receded in 9867 +/- 39 cal BP. However, the presence of aquatic herbaceous forms such as Nymphaceae and Cyperaceae indicates an increase in the water level of the lake during 6776 +/- 35 cal BP, after which it transitioned to a dried lake. Thus, the progression and recession phases of the lake became the determining factor in the site selection of Neolithic settlements on mounds by which are found the plain floor at elevations between 1090 and 1100 m in this period on the Bor Plain.Öğe Trends and changes in tropical and summer days at the Adana Sub-Region of the Mediterranean Region, Southern Turkey(Elsevier Science Inc, 2017) Altin, Turkan Bayer; Barak, BelmaIn this study, the long-term variability and trends of the annual and seasonal numbers of summer and tropical days of the Adana Sub-region were investigated using nonlinear and linear trend detection tests for the period 1960-2014 at 14 meteorological stations. The results suggest that the annual number of summer and tropical days was generally below the long-term average through to the end of the 1980s. In particular, positive anomaly values could be observed at all stations between the years 1993-2014. With respect to the Kruskal-Wallis homogeneity test, the significant breaking date was 1993. The rapid rise of the annual number of summer (tropical) days after this year led to the inversion of the negative trends observed from 1987 to 1992 into positive ones. The increasing trend is statistically significance at 0.01 level in Yumurtalik, Mersin and Antalya for the annual number of summer and tropical days. Dortyol, Iskenderun and Elbistan were significance at 0.01 level for tropical days. The largest positive anomalies of the summer of 2010 are observed in coastal vicinity (Mersin, Yumurtalik and Iskenderun). This indicates that these settlements underwent a long-term warm period and thermal conditions due to increasing temperatures in the spring and summer months. The same conditions are found in high inner areas (Goksun and Elbistan) for tropical days. It is noticed that a tendency for greater warming occurred at stations located above 1000 m in the sub-region. The average number of warm days will increase 2-days per 100-years in southern part of the sub-region. The increasing trend in summer temperatures can be considered a potential risk, notably for human health and for economic and crop losses in the Adana Sub-region, including cukurova, one of the most important agriculture areas of Turkey.
