Drought analysis according to shifting of climate zones to arid climate zone over Asia monsoon region

- Precipitation and runoff appeared to decrease, while temperature increased in shifted zones.
- Most of the shifted zones had strong decreasing trend of drought index.
- Change point of drought occurred several years earlier than the zone shifting.
- Frequency, duration and severity of droughts increased in shifted zones.

SummaryWhen a humid region is affected by arid climate, significant changes in drought characteristics occur due to imbalance of water budget. In this study, change in drought characteristics according to shift of different climates i.e. tropical, warm temperate, cold and polar to Arid Climate (SAC) was analyzed over the Asia monsoon region. Climate zones and the SAC regions were identified by applying the Köppen climate classification on hydro-meteorological data for the period of 1963-2006. The analysis of hydro-meteorological parameters revealed that the annual precipitation and runoff in the SAC regions appeared to decrease about 12.1% and 27.3%, respectively, while annual average temperature increased about 0.5 °C. Standardized runoff index (SRI) was calculated using model-driven runoff data. The trend and change point analyses of SRI were performed to evaluate the changes in drought characteristics (frequency, duration, severity) before and after shifting of the different climates to arid climate. The results revealed strong decreasing trend of SRI and hence intensified drought conditions for the SAC regions. A change point year of drought occurred about 3-5 years earlier than the shifting time of the SAC region. Frequency and duration of droughts in the SAC regions were observed to increase about 9.2 and 1.5 months, respectively, and drought severity index intensified to about −0.15. It can be concluded that analysis of shifting to arid climate zones should be considered together with changes in drought characteristics, because the drought characteristics and changing arid climate zones are closely related to each other.