Adapting the regional frequency analysis based on L-moments to improve the standardized precipitationevapotranspiration index

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dc.citation.journaltitleBRAGANTIA
dc.creatorMARTINS, L. L.
dc.creatorSOBIERAJSKI, G. R.
dc.creatorBLAIN, G. C.
dc.date.accessioned2026-05-05T17:57:19Z
dc.date.issued2024
dc.description.resumoThe standardized precipitation-evapotranspiration index (SPEI) is a widely used probability-based method that categorizes drought and wet events based on their expected frequency of occurrence. Regional frequency analysis based on L-moments (RFA-Lmom) is often employed to enhance probabilistic assessments of extreme hydrological data, which typically assume positive values. This study investigated whether applying the RFA-Lmom regionalization technique to the difference between precipitation and potential evapotranspiration (P-PE), the input variable for SPEI, can improve the index’s ability to meet the normality assumption. We conducted analyses using Monte Carlo experiments, accounting for distinct climate conditions worldwide, and a case study in the watershed of the Piracicaba, Capivari and Jundiaí rivers, situated in the states of São Paulo and Minas Gerais, Brazil. In this region, P-PE frequency distributions may exhibit negative and positive sample means. Our findings suggested that modifying the RFA-Lmom method by replacing the L-moment ratio L-CV with the L-moment scale measure and using an additive model (instead of the original multiplicative procedure) for SPEI calculation allows the application of this regionalization technique to P-PE amounts. This adapted RFA-Lmom consistently enhanced the ability of SPEI frequency distributions to meet their normality assumption, thereby improving the quality of drought assessments based on this standardized index.
dc.format.extente20240029
dc.format.issue83
dc.identifier.citationMartins, L. L., Sobierajski, G. R. and Blain, G. C. (2024). Adapting the Regional Frequency Analysis based on L-moments to improve the Standardized Precipitation-Evapotranspiration index. Bragantia, 83, e20240029. https://doi.org/10.1590/1678-4499.20240029
dc.identifier.doihttp://dx.doi.org/10.1590/1678-4499.20240029
dc.identifier.urihttps://repositorio.iac.sp.gov.br/handle/iac/158
dc.subjectdrought, additive approach, normality assumption, L-moments
dc.titleAdapting the regional frequency analysis based on L-moments to improve the standardized precipitationevapotranspiration index

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