Bivariate Hazard Assessment of Combinations of Dry and Wet Conditions between Adjacent Seasons in a Climatic Transition Zone

Accumulated evidence reminds one that abrupt transitions between dry and wet spells, though attracting less attention, have harmful influences upon global continents as extensively investigated droughts floods. This study attempts to incorporate dryness–wetness into the current hazard assessment framework through bivariate frequency analysis causal attribution from a teleconnection perspective. In study, regional conditions are monitored using multivariate standardized drought index (MSDI) which facilitates integrated evaluation of water deficits/surplus combined viewpoint precipitation (largely denoting received atmospheric water) runoff (representing an important source surface water). On such basis, copula-based method is subsequently utilized calculate joint return periods combinations in three (i.e., moderate, severe extreme) severity scenarios. The changing diverse also estimated under climate 25-year time window. Furthermore, cross-wavelet transform applied attribute variations large-scale indices, benefits early warning by providing predictive information. A case conducted during 1952–2010 Huai River basin (HRB)—a typical climatic transition zone China—shows HRB subject prolonged dryness with highest frequency, followed wetness. Spatially, more likely occur southern central parts than rest proportion. past half-century has witnessed dominantly higher occurrence particular, continued dry/wetness escalates rapidly events change. Moreover, preliminary discloses link El Niño oscillation, Pacific decadal oscillation Arctic well sunspot activities. results enrich atlas water-related hazards, may benefit effective mitigation adaptation.