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Assessing Multi-site Drought Connections in Iran Using Empirical Copula.

Shiau, Jenq-Tzong; Modarres, Reza; Nadarajah, Saralees (2012). Assessing Multi-site Drought Connections in Iran Using Empirical Copula. Environmental Modeling & Assessment , vol. 17 , nº 5. p. 469-482. DOI: 10.1007/s10666-012-9318-2.

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Résumé

Drought is a multi-dimensional natural hazard with stochastic characteristics usually related to each other. Separate univariate statistical models cannot capture the important relationships among drought characteristics, that is, severity and duration. In this study, an empirical copula is employed to construct a bivariate model of droughts, where droughts are defined as continuously negative standardized precipitation index (SPI) periods with one SPI value reaching −1 or less. Bivariate frequency analyses in terms of recurrence intervals are performed using the established empirical copula-based bivariate drought model. The inter-connection among different regions of droughts is explored by a lower tail dependence coefficient. A nonparametric estimation based on an empirical copula is employed pairwisely to calculate the lower tail dependence coefficient among stations. The proposed method is applied to six rainfall gauge stations in Iran to explore drought properties of single sites as well as the inter-connection among multi-sites. The results show that greater mean drought severity and duration are associated with the least arrival rate of drought events, which occurs at the Ahwaz station. The tail dependence analysis reveals that distance between stations is not a key parameter. Generally, the Ahwaz and Isfahan stations have the highest probability of simultaneous droughts among the six stations.

Type de document: Article
Mots-clés libres: drought; standardized precipitation index (SPI); empirical copula; tail dependence coefficient; Iran
Centre: Centre Eau Terre Environnement
Date de dépôt: 19 oct. 2018 15:01
Dernière modification: 19 oct. 2018 15:01
URI: http://espace.inrs.ca/id/eprint/7297

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