Analysis of Characteristics of Dry–Wet Events Abrupt Alternation in Northern Shaanxi, China

Abstract

In this study, Yulin city and Yan’an city in northern Shaanxi Province were taken as the study area. Based on the diurnal dry–wet events abrupt alternation index DWAAI, the joint probability distribution of two characteristic variables of “urgency” and “alternation” of dry–wet events abrupt alternation was established by using copula function, and the characteristics of dry–wet events abrupt alternation were analyzed. DWAAI was calculated from daily precipitation data and the applicability of the index was verified. On this basis, the two characteristic variables of “urgency” and “alternation” were separated, and the appropriate marginal distribution function was selected to fit them, and the correlation between the two variables was evaluated. Finally, the appropriate copula function was selected to fit the bivariate of each station, and the joint cumulative probability and recurrence period of the two variables were calculated. The results show that the DWAAI index is suitable for the identification of dry–wet events abrupt alternation in the study area. Light and moderate dry–wet events abrupt alternation occurs more frequently, while severe events rarely occur in the study area. The frequency of severe dry–wet events abrupt alternation in Jingbian station and its northern area is greater than that in the southern area, and the risk of dry–wet events abrupt alternation of disasters in the northern area is higher. The greater the degree of “urgency” and “alternation”, the greater the joint cumulative probability and the greater the return period. The return period of severe dry–wet events abrupt alternation was more than five years, while the return period of light and moderate dry–wet events abrupt alternation was less than five years.

Identification, physical mechanisms and impacts of drought–flood abrupt alternation: a review

“…Several studies have introduced the percentage anomaly (Pa) of precipitation and the continuous days without available precipitation (Dnp) into the identification of DFAA (Qin et al, 2019;Wang J. H. et al, 2021a). However, the number of case studies is not sufficient to test the representativeness and stability of this index.…”

“…And just like any other multi-hazard event, a DFAA can pose a greater threat to ecoenvironment, social and humanistic systems than a single flood or a drought event (Zhou & Liu, 2018;De Luca et al, 2020;Xue et al, 2022). To keep up with the increasing frequency of DFAA occurrence, more researchers have put great effort in the study of DFAA (Tang & Shao, 2007;Wang et al, 2012;Xiong W. et al, 2017a;Yang, et al, 2019a;Qin et al, 2019;Wang J. H. et al, 2021a;Gao & Zhao, 2022). Tendency of publications on DFAA topic is shown in Figure 1.…”

Global evidence of rapid flash drought recovery by extreme precipitation

“…The postflash drought phase brings the potential for flooding and its associated challenges, uncovering a complex interplay between different climatic factors and the resulting ecological impacts (Nanditha and Mishra 2021, You and Wang 2021, You et al 2023. Pluvial events with extreme precipitation after droughts have profound implications (Esteban et al 2021, Wang et al 2021). For instance, over two weeks, heavy rainfall rapidly terminated a flash drought in the late summer 2015 in the South-Central United States, indicating cascading dry-to-wet effects in the region (Otkin et al 2019).…”

Spatial-Temporal Variations of Drought-Flood Abrupt Alternation Events in Southeast China

“…The DWAAI, which identifies DFAA events on a daily time scale, can assess the difference in intensity between droughts and floods during early and late stages as well as determine the urgency of transitioning. However, the parameter involved in the DWAAI (i.e., the attenuation coefficient) needs to be adjusted according to the geographical environment [17,18]. Additionally, the range of drought and flood values varies across different regions, which lacks consistency.…”