Abstract: The characteristics of climate change and evolution of drought and flood disasters in Maerkang City were examined through tests of climate tendency rate,abrupt change,signal-to-noise ratio,and cycle estimation based on the measured data of monthly temperature and precipitation from 1954 to 2019.The driving factors of drought and flood disasters were verified via ADF test and Granger causality analysis.The average annual temperature and annual precipitation showed a significant upward trend,and the climate tended to be warm and humid.The average annual precipitation increased at a rate of 16.29 mm/10a,obvious in summer and autumn while to the minimum in spring.Climate changed abruptly in 2001,after which the drought and flood disasters increased and the extreme flood events became more frequent.The years from 2015 to 2019 witnessed a large flood event.Both sunspot activity and ENSO(El Nin~o-Southern Oscillation) events are Granger causes of precipitation variation.The ENSO events and the drought and flood disasters have synchronous resonance period in 6.6 years.The ENSO event with a lag period of two years is one of the main causes of the changes in drought and flood disasters.ENSO events provide an important theoretical support for regional drought and flood warning on an annual scale.

Key words: abrupt climate change, drought and flood disasters, Granger causality, ENSO event, Maerkang city