Drought-flood abrupt alternation (DFAA) refers to a rapid transformation between droughts and floods

which poses great threats to agricultural production and human security. This study

based on the monthly scale magnitude index of DFAA

analyzes four types of historical and future DFAA events in the Yangtze River basin. A time-varying function for the magnitude of DFAA is constructed using a sliding window approach

revealing the future changes in DFAA risk. Shared socio-economic pathways are integrated to quantify the impact extent of changing risk of DFAA on population and economy. The results show that in historical periods

the hotspots of the DFAA events were mainly distributed in the middle and lower reaches of the basin

with drought-flood and flood-drought events occurring 10 - 12 times per decade

and drought-flood-drought and flood-drought-flood events occurring 3 - 4 times per decade. Drought-flood-drought and flood-drought-flood events are projected to significantly increase in the future for the whole basin

and parts of it will experience a growth of approximately seven times. For the historically recorded 50-year DFAA events

the probability of their occurrence will increase by 5 to 10 times in the future

and the population and economy of the basin will be significantly affected.