Today, within the scope of planning, development and management of water resources affected adversely by climate change, the issue of minimization of the adverse effects of drought has become very important. In this study, drought risk analyses were performed using meteorological, hydrogeological and hydrological data of the Asi basin and as a result of the determination of different indices and indicators available in the literature. First, the missing data was completed by regional analyses. The DI (Deciles Index), SPI (Standardized Precipitation Index), SPEI (Standardized Precipitation Evapotranspiration Index) and SRI (Standardized Runoff Index) indices were described. Drought severity and magnitude were found according to these indices. Based on 1, 3, 6, 9, 12, 48-month recurrence intervals, analyses were made. Classification of droughts and their threshold values were determined. For some places, drought incidence rates were presented according to each index. The indices were compared, the correlation between them was examined and a common conclusion was reached. The drought severities, which has a precipitation area of 7800 m2, were evaluated for certain recurrence intervals. For this purpose, based on meteorological, hydrological and hydrogeological data for the years between 1970 and 2016, DI, SPI, SPEI, and SRI indices were analyzed and compared.

Climate change and global warming are among the issues that humanity is most concerned about the future. The growing drought and flood risks that increase despite the taken measures have led to the adoption of an integrated understanding on the topic of water management in recent years. To manage the increased risk of drought and to make sustainable planning, the dimensions of drought should be known first. For this purpose, many drought indices have been developed. The Normalized Difference Vegetation Index (NDVI) and Vegetation Condition Index (VCI), which determined by remote sensing, are two of these. In this study, in which the agricultural drought was analyzed with vegetation indices by taking into consideration the historical drought archive, the Asi Basin was addressed. The data of the Asi Basin, which covers an area of 7800 km 2 and was obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Advanced Very High-Resolution Radiometer (AVHRR) satellites, was used in this study. With the satellites benefited in remote sensing and with the Coordination of Information on the Environment (CORINE), where the layers of vegetation were determined, agricultural and forest areas were evaluated separately. The vegetation indices, which change with the increase in temperature, have revealed the necessity of a long-term drought management for the Asi Basin. Result of the work pointed that NDVI index is more appropriated to the Asi Basin than the VCI index to monitor drought.

Climate change is leading one of the main research topic that today's science world is worried about the future. Increased risks of droughts and floods, resulting from this, have led to the adoption of a holistic understanding of water management in recent years. The tendency of drought should be known in order to manage the increased drought risk and to make a sustainable plan. Drought is a hydrological event that begins and progresses slowly, so monitoring and analysis are of great importance. In addition to many tests, the Mann-Kendall test is one of the most common and respected trend analysis tests. In this study, it was investigated whether there is a drought tendency for the Asi basin, which has an area of about 7800 km 2 . For this purpose, meteorological, hydrological and hydrogeological data between 1970 and 2016 were considered. The tendency of precipitation, flow, evaporation, temperature and groundwater data for years has been studied in detail and the risk of drought has been investigated for the Asi basin. First of all, meteorology and flow observation stations in the basin were determined to be suitable ones and the missing data were completed by methods appropriate to the literature. As a result of these analyzes, the Asi basin was found to have an upward trend, though not statistically significant, at 95% confidence level in annual total precipitation. On average annual temperatures, there was a clear upward trend for both sub-basins and watersheds.

Various drought indices have been developed to monitor drought, which is a result of climate change, and mitigate its adverse effects on water resources, especially in agriculture. Vegetation indices determined by remote sensing were examined by many recent studies and shed light on drought risk management. In the current study, one of the 25 drainage basins in Turkey—the Seyhan Basin, located in the south of the country—was investigated. The Normalized Difference Vegetation Index (NDVI) and the Vegetation Condition Index (VCI) are the most widely used vegetation indices and are very useful because they give results only based on satellite images. This study examined the Seyhan Basin using satellite data in which the vegetation transformation occurring due to the decline of agricultural and forest areas was seen. An increase in drought frequency was detected in the Seyhan Basin using the NDVI and VCI indices and compared with different indices. The results obtained revealed that climate change and drought is increasing with a linear uptrend. It is recommended that decision-makers take the necessary measures by considering the drought risk maps. Long-term drought management plans should also be prepared and implemented.

ÖzetKuraklık, geniş alanlarda ve belirli bir zaman aralığında su kullanımının önemli derecede azalmasını tarif eden doğal bir olaydır. Dünyanın değişik bölgelerinde meydana gelen kuraklık, ekonomik faaliyetlere, insan yaşamına ve ekosistem ile alakalı çeşitli faktörlere etki eder. Küresel hidrolojik çevrimin karmaşık olması nedeni ile kuraklığın kökenini belirlemek gerçek anlamda mümkün olamamaktadır. Ancak küresel ısınmanın yanında şehirleşmenin etkisi yadsınamaz bir gerçektir. Bu çalışmada, Seyhan havzasında ölçülmüş olan aylık ortalama yağış, sıcaklık ve su tutma kapasiteleri kullanılarak Palmer kuraklık şiddeti indisi (PDSI) metoduna göre kuraklığın saptanması hedeflenmiştir. Seyhan Havzası kuraklık analizi çalışması kapsamında kullanılacak meteorolojik, hidrolojik ve hidrojeolojik veriler için veri boşluk analizi yapılarak veri varlığı değerlendirilmiş, en uzun ve uygun ortak periyot olarak meteorolojik verilerin analizinde 1970-2016, hidrolojik ve hidrojeolojik verilerin analizinde 1970-2015 yılları esasa alınmıştır. Seyhan havzasında yavaş ilerleyen bir kuraklık olduğu kanaatine varılmıştır.Anahtar Sözcükler: Kuraklık, Seyhan Havzası, Palmer kuraklık indisi GirişGünümüzde iklim değişikliğinin olumsuz olarak etkilediği su kaynaklarının planlaması, geliştirilmesi ve yönetimi çalışmaları kapsamında, kuraklığın beklenen etkilerinin hafifletilmesi konusu oldukça önem kazanmıştır. Artan kuraklık riskinin yönetilmesi ve bu riske uyum sağlanması; ancak bütüncül yaklaşımları benimseyen sürdürülebilir ve etkili kuraklık risk yönetimi stratejilerinin geliştirilmesi ile olur. Kuraklık yönetimi afet yönetiminin bir parçasıdır. Kuraklık Risk Yönetimi; korunma, zarar azaltma ve hazırlıklı olma amaçlı faaliyetler ve önlemler yoluyla kuraklık tehlikesinin olumsuz sonuçlarını ve potansiyel afet etkilerini engelleme ve azaltma kavramı ve çalışmasıdır. Kuraklığı üç ana başlıkta tarif edebiliriz; 1) Meteorolojik kuraklık; genellikle göreceli olarak daha kısa zaman zarflarında (1-6 ay) gerçekleşen yağış verisinin kullanıldığı indikatörler ve indeksler ile analiz edilmektedir. 2) Hidrolojik kuraklık; yüzey ve yer altı suyu verileri kullanıldığı ve göreceli olarak daha uzun zaman zarflarında (6-12 ay) gerçekleşen yağış verilerinin kullanıldığı indikatörler ve indeksler sayesinde tespit edilmektedir. 3) Tarımsal kuraklık; bitki için gerekli olan toprak neminin yeterli değerin altında olması ile özdeşleştirilmesi sebebiyle genellikle uzaktan algılama yöntemleri ile elde edilebilen bitki örtüsü ve toprak nemi verilerinden hesaplanan indeksler sayesinde ve meteorolojik veriler ile bitkisel üretim verileri yoluyla tespit edilmektedir. Farklı zaman dilimlerinde etkili olabilen kuraklık olaylarının incelenmesi ve izlenmesi amacıyla çeşitli yaklaşım ve yöntemler geliştirilmiştir. Geliştirilen yöntemlerde yer alan indikatörler, indeksler ve eşik değerler kuraklık koşullarının başlangıcını saptamak, kuraklık 273