Assessment of Drought Conditions Over Different Climate Zones of Kazakhstan Using Standardised Precipitation Evapotranspiration Index

摘要

The present research was carried out to understand the long-term changes in drought conditions over major climate regions of Kazakhstan using the temperature-sensitive Standardised Precipitation Evapotranspiration Index (SPEI). The inter-annual and intra-annual drought events were studied by computing SPEI at resolute time scales such as SPEI 1, SPEI 3 and SPEI 12. The non-parametric statistical metrics including the Mann-Kendall test and Sen's slope estimator were used to find the direction and magnitude of trends shown by the index. The results of the study revealed a significant drying tendency of the arid and semi-arid climate zones. An insignificant wetting tendency was observed for the humid and sub-humid climate zones of the country. The analysis of SPEI 3 showed that the summer and autumn seasons made a significant contribution to the dry periods in the semi-arid climate zone while the spring season aided in generating a similar downward trend in the arid climate zone. April, August and September were recorded as the months with the highest occurrence probability of total droughts in all the climate divisions of Kazakhstan. Until the point of probable meteorological change in 1994; the central longitudinal position occupied by the highest possibility occurrence areas for overall droughts showed a westerly and north-easterly shift during the subsequent period. The drought index also reflected an increased occurrence probability of all types of droughts with an obvious shift in the intensive drought centers during the studied time slices. However, the range of occurrence probability shrank with the increasing severity of droughts.