Abstract
Abstract. In this study, the meteorological drought represented by Standardized Precipitation Evapotranspiration Index (SPEI) and agriculture drought represented by Vegetation Condition Index (VCI) are analysed in seven regions over Turkey. VCI calculated using the Normalized Difference Vegetation Index (NDVI) data obtained from NOAA AVHRR, SPEI obtained from the SPEI global database with the version (SPEI base v2.5), and Land use/cover obtained from CORINE datasets. The study covers the period from January 1982 to December 2015 due to the availability of NDVI data. The correlation between monthly and seasonal VCI and SPEI (lag months 1, 3, 6, 9, and 12) was investigated in a regional and provincial scale. Monthly correlation found to be the highest in the Central Anatolia, Aegean, Marmara and Mediterranean regions respectively, while other regions have lower and non-homogenous values. One lag time of the VCI with respect to SPEI 12 improves the correlation. The regional correlation showed that, the highest correlation between two parameters is obtained for all the regions with SPEI 12 during summer, then followed by Autumn, and Spring months, the maximum values are recorded for the Central Anatolia (0.656) and Mediterranean (0.625) in Summer, and Aegean (0.643) in Autumn respectively; rather lower correlation values did occur in Marmara (0.515) in Autumn, Eastern Anatolia (0.501), SE Anatolia (0.375) and Black Sea (0.297) regions in Summer. The provincial investigation between seasonal VCI and SPEI indicated that the presence of a positive correlation in general in most of the provinces in all seasons with several exceptions in the Eastern Anatolia, South eastern Anatolia, Black sea, and Marmara. The land cover types with high correlation coefficients are noticed to be covered by forest, agricultural lands, non-irrigable lands and mostly covered by fruits (grape, olive etc.) using CORINE land cover map.
Highlights
Drought is a stealthy climate disaster that heavily affects all the aspect of the natural environment and human beings (Mishra and Singh 2010)
The main objective of this study is to investigate the monthly and seasonal variation of the correlation between the Vegetation Condition Index (VCI) and Standardized Precipitation Evapotranspiration Index (SPEI) with several temporal scales (1,3,6, 9, and 12) where these two indices are indicators of Agricultural and Meteorological droughts respectively
The trends of VCI are significantly increasing in all regions and the increase values are higher than the ones in the SPEI trends
Summary
Drought is a stealthy climate disaster that heavily affects all the aspect of the natural environment and human beings (Mishra and Singh 2010). Droughts affect surface and groundwater resources leading to several problems such as: reduction in water supply, deterioration in the water quality, reduction in power generation, decrease in productivity, failure of crop, distribution of riparian habitats, and eventually suspension of recreation activities including the host of economic and social activities (Mishra and Singh 2010; Riebsame, Changnon Jr, and Karl 1991). Drought can be defined as: deficit in the precipitation, deviation from the normal hydrologic condition, the percentage of the years in which crops fail due to the scarcity of moisture (Dabanlı, Mishra, and Şen 2017). Droughts mostly depend on the decrease in the amount of the precipitation received through a long period that could be a season or a year
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