Drought analysis using satellite observations over-Turkiye

Drought is a natural hazard that occurs when rainfall declines for an extended period of time compared to seasonal normal rainfall. It directly affects human life, environment, economy, ecology and agriculture as well as public health, and prosperity. Therefore, its identification along area and time needs special importance. This study aims to investigate the spatial-temporal behavior of drought in the watersheds of Turkiye, based on pixel-based precipitation, temperature and terrestrial water content data. GRACE (Gravity Recovery and Climate Experiment) satellite data is used to obtain the long-term terrestrial water content. PERSIANN (Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks) satellite data is used to obtain monthly long-term basin-scale precipitation changes. The temperature aspect of drought is investigated by means of WorldClim dataset. Spatial analyses are implemented in GIS environment to find out the regional temporal mean, max, and mins of these variables (i.e. terrestrial water storage, precipitation, and temperature). The temporal behavior of those basin-based variables is analyzed by time series analysis and basins under drought impacts have been determined using t-test. The study has shown that almost all Turkish basins have been suffering from the impact of drought, especially after 2016. It is also concluded that GRACE provides high-value realistic images of the temporal behavior of hydrological drought whereas, PERSIANN show only years with extreme characteristics of meteorological drought. In addition, PERSIANN data and SPI (Standardized Precipitation Index) produced similar results for the identification of basins under drought impact while WORLDCLIM temperature data are not providing a reliable estimation of temporal drought behavior. Keywords: Drought, Precipitation, Natural hazard, Satellite Data, Remote Sensing, GIS, SPI GRACE, PERSIANN