DROUGHT CHARACTERISATION OF SYRDARYA RIVER BASIN IN CENTRAL ASIA USING RECONNAISSANCE DROUGHT INDEX

This study provides a comprehensive analysis of drought characteristics in Syrdarya River Basin (SRB) of Central Asia (CA) by using meteorological and environmental variables derived from reanalyzed information database. Drought Intensity and Frequency (DIF) curves were identified based on precipitation deficit and evapotranspiration rates by using Reconnaissance Drought Index (RDI). Climatic variables for the study period of 1985-2015 were derived from Climate Research Unit (CRU) database. The frequency and duration of events appearing from April to September of each year, and drought severity was calculated as the sum of an integral period from severe to the extreme range defined with RDI varied between -1.5 and -3, respectively. Several drought events, ranging between moderate, severe and extreme in past 30 years period, were revealed over the basin in this study. A significant decreasing trend at high elevations in contrast to obvious increasing trends at lower elevations of the river basin has been observed. The dynamic variations of drought events over the SRB indicates the variation patterns of climatic impacts on drought occurrences in the mountainous regions.