Bir bölgede nem miktarının geçici dengesizliğinden kaynaklanan su kıtlığı olarak tanımlanabilen kuraklık, doğal bir iklim olayıdır. Temel olarak yağışların beklenen değerlerin altında gerçekleşmesi sonucu kuraklık meydana gelir, sürenin uzamasıyla birlikte etkisi giderek artar. Meteorolojik karakterli doğal afetler kategorisinde yer alan kuraklığın kapsamı geniştir ve birçok sektör üzerinde negatif önemli etkilere sahiptir. Kuraklığın olumsuz etkilerinin bertaraf edilebilmesi için kuraklık karakteristiklerinin bilinmesi önem taşımaktadır. Kuraklık şiddet, süre ve frekans gibi değişkenlerle karakterize edilebilir. Bu çalışmada Trakya . . .’dan Meriç-Ergene, Ege Bölgesi’nden Gediz ve Akdeniz Bölgesi'nden Seyhan ve Ceyhan havzalarından seçilen yağış gözlem istasyonlarına ait kuraklık karakteristikleri belirlenmiş, kuraklık şiddetsüre-frekans eğrileri Standart Yağış İndeksine göre elde edilmiştir. Bu indeks kullanılarak 2, 5, 10, 25, 50 ve 100 yıllık dönüş aralıklarına karşı gelen kuraklık şiddet-süre-frekans eğrileri her bir istasyon için hazırlanmıştır.
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Drought which is one of the most injurious natural hazards is defined as lack of rainfall that leads to a temporary decrease or deficit in natural water availability. Droughts may result in long-term environmental, social and economic impacts. Therefore, drought forecasting is an important hydrological phenomena and it plays a major role in risk management, drought preparedness and the implementation of mitigation measures. The objective of this study is to analyze drought characteristics of Meric-Ergene, Gediz, Seyhan and Ceyhan hydrological basins in Turkey. Standardized Precipitation Index (SPI) is used in drought analysis based . . .on the monthly precipitation data from meteorological stations. Frequency analysis using SPI has implemented for the derivation of drought severity-duration-frequency curves corresponding to 5, 10, 20, 50 and 100-year return periods.
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Kuraklık karakteristiklerinin belirlenmesi sürdürülebilir su kaynakları yönetiminde, kuraklığa karşı alınacak önlemlerde ya da kuraklık eylem planlarının hazırlanmasında büyük rol oynamaktadır. Kuraklık, kuraklık şiddeti, süre ve frekans gibi değişkenlerle karakterize edilebilmektedir. Çalışmanın amacı; kuraklık şiddeti-süre-frekans eğrilerini elde etmek, böylelikle kuraklığın etkilerinin azaltılmasını sağlamaktır. Kuraklık karakteristikleri yağış verisine dayanan Standart Yağış İndeksi (SYİ) kullanılarak belirlenmiştir. Standart Yağış İndeksi; yalnızca yağış verisine ihtiyaç duyması, hesaplamalardaki kolaylığı ve güvenilir olması n . . .edeniyle sıkça kullanılmaktadır. Standart Yağış İndeksi 1, 3, 6, 9, 12, 24, 48 ay gibi farklı periyotlar için hesaplanabilir. Uygulama için Meriç-Ergene hidrolojik havzasında bulunan Meteoroloji Genel Müdürlüğü’ne ait 17050 no.lu Edirne meteoroloji gözlem istasyonu seçilmiştir. Bu istasyondan temin edilen aylık yağış verileri kullanılarak 1, 3, 6, 9, 12 ve 24 aylık periyotlar için Standart Yağış İndeksleri hesaplanmıştır. Hesaplanan indeksler kullanılarak 2, 5, 10, 25, 50 ve 100 yıllık dönüş aralıklarına karşı gelen kuraklık şiddeti-süre-frekans eğrileri elde edilmiştir
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In this study, duration-frequency curves were developed for D = 1, 7, 14, 30, 90 and 273-day low flows corresponding to the 2, 5, 10, 25, 50 and 100-year return periods. For this, daily data acquired from streamflow gauging stations with minimized anthropogenic effects were used. A hybrid frequency analysis coupled with the total probability theorem was applied on D-day low sequences to accommodate zero values. Among the tested probability distribution functions, Generalized Extreme Value was found the best in fitting low flows for majority of cases. Low flow discharge increases with increasing duration while it decreases with incre . . .asing return period for a given duration. Low flow duration-frequency curves can be considered one among significant tools to be used by the hydrological community in water resources planning and management
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Drought is a natural phenomenon and integral part of climate variability. It has been a fact that drought event develops gradually without being noticed, causes insidious natural hazard and serious harm. Therefore, it is a must to characterize frequency, severity and duration of a drought. The objectives of this study were three-fold: 1) to show versatility of standardized precipitation index (SPI) for 6- and 12-month timescales in order to explore both wet and/or dry periods and precipitation thresholds for the onset of drought by using relatively long-term monthly precipitation data; 2) to develop drought severity-duration-frequen . . .cy (SFD) curves; 3) to find a way for drought severity transformation to precipitation deficit for different return periods and drought durations. Monthly precipitation data of 87-year record length from Adana meteorological station were used in the study. SPI series of the two timescales were concordant with the historical drought experienced in the region. The 6-month moving cumulative precipitation thresholds varied between 125 mm (in October) and 487 mm (in April); it was 630 mm for the 12-month timescale. The longer a drought duration happens, the higher precipitation deficit is expected for timescales considered. SDF curves were helpful in delivering 6- and 12-month moving cumulative precipitation deficits for drought durations and return periods.
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Although the complexity of physically-based models continues to increase, they still need to be calibrated. In recent years, there has been an increasing interest in using new satellite technologies and products with high resolution in model evaluations and decision-making. The aim of this study is to investigate the value of different remote sensing products and groundwater level measurements in the temporal calibration of a well-known hydrologic model i.e., Hydrologiska Bryans Vattenbalansavdelning (HBV). This has rarely been done for conceptual models, as satellite data are often used in the spatial calibration of the distributed . . . models. Three different soil moisture products from the European Space Agency Climate Change Initiative Soil Measure (ESA CCI SM v04.4), The Advanced Microwave Scanning Radiometer on the Earth Observing System (EOS) Aqua satellite (AMSR-E), soil moisture active passive (SMAP), and total water storage anomalies from Gravity Recovery and Climate Experiment (GRACE) are collected and spatially averaged over the Moselle River Basin in Germany and France. Different combinations of objective functions and search algorithms, all targeting a good fit between observed and simulated streamflow, groundwater and soil moisture, are used to analyze the contribution of each individual source of information. Firstly, the most important parameters are selected using sensitivity analysis, and then these parameters are included in a subsequent model calibration. The results of our multi-objective calibration reveal a substantial contribution of remote sensing products to the lumped model calibration, even if their spatially-distributed information is lost during the spatial aggregation. Inclusion of new observations, such as groundwater levels from wells and remotely sensed soil moisture to the calibration improves the model's physical behavior, while it keeps a reasonable water balance that is the key objective of every hydrologic model
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6698 sayılı Kişisel Verilerin Korunması Kanunu kapsamında yükümlülüklerimiz ve çerez politikamız hakkında bilgi sahibi olmak için alttaki bağlantıyı kullanabilirsiniz.
