Abstract
With the increase of drought and flood frequency, the drought-flood abrupt alternation events occur frequently. Due to the coexistence and rapid transformation of drought and flood, the drought-flood abrupt alternation events is often more harmful and threatening than the single drought or flood event to the security of the society. This study is to synthetically evaluate the evolving characteristics of drought, flood, and drought-flood abrupt alternation events under climate change, which are identified by using the Standard Weighted Average Precipitation (SWAP) index. The variability of drought, flood, and drought-flood abrupt alternation events in the future is predicted by using GCM projections, whose outputs are corrected by using a daily bias correction method. The results show that: (1) The SWAP index has the capability to judge reliably the onset, duration, and intensity over the study areas, and can be used to monitor drought-flood abrupt alternation events efficiently; (2) In the reference period (1961–2005), for the drought-flood abrupt alternation events, the frequency has a downward trend in the upper reaches and an upward trend in the lower reaches, and the spatial distribution of intensity shows a contrary law to that of frequency; (3) The frequency and intensity of drought-flood abrupt alternation events show an upward trend in the whole basin in the future period (2021–2095), under the RCP4.5 and RCP8.5 scenarios. These results indicate that drought-flood abrupt alternation events can be more frequent, and the intensity will significantly increase in the 21st century, which may likely pose a serious impact on this basin.
Highlights
Drought and floods are global problems and the world’s most damaging and pressing natural hazards [1,2], causing billions of dollars in global damage and collectively affecting more people than any other climate-related disaster
To thoroughly validate the Standard Weighted Average Precipitation (SWAP) index, the robustness of the SWAP index is evaluated at different timescales to show if it is capable of capturing current drought and flood conditions in the historical period (1961–2017)
This study investigates and estimates the spatio-temporal variation of meteorological drought, flood, and drought-flood abrupt alternation events under the climate change in the Hanjiang Basin
Summary
Drought and floods are global problems and the world’s most damaging and pressing natural hazards [1,2], causing billions of dollars in global damage and collectively affecting more people than any other climate-related disaster. Meteorological drought and flood are a reflection of extreme rainfall events, the characteristics of which are difficult to objectively quantify in terms of frequency, intensity, duration, and spatial extent. Many evaluation methods for meteorological drought and flood have their limitations, and how to find good applicability from many methods is often affected by factors such as river basin meteorological factors, climate change, and human activities. For this reason, an effective drought assessment method is important for drought analysis and monitoring. Some studies indicated that extreme drought and flood would further increase in the. 21st century because of global climate change and the intensification of anthropogenic activities [3,4,5].
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