Drought analysis in southern Paraguay, Brazil and northern Argentina: regionalization, occurrence rate and rainfall thresholds

Abstract

The objective of the present study is to characterize the drought occurrences in a region comprising Paraguay, southern Brazil and northeastern Argentina. To recognize the drought occurrences the standardized precipitation index at the time-scales of 3 and 6 months was applied to the rainfall records from 1961 to 2011 at 51 rain gauges located in that region. After a drought regionalization using principal component analysis, a new approach, the Kernel occurrence rate estimation method coupled with bootstrap confidence band was used to quantify yearly drought occurrence rates. The study also includes the results of an additional and new approach based on rainfall threshold surfaces aimed at recognizing and monitoring the drought occurrence at the early stages of their development. For both time-scales, the study allowed identification of some spatial homogeneous regions regarding the severe droughts. In some of those regions, trends in the severe drought frequency occurrence were identified. The rainfall threshold surfaces, besides providing an adequate interpretation of the meaning of the standard precipitation index, can be quite easily and reliably utilized to identify the drought episodes.

Copula-Based Multivariate Frequency Analysis of the 2012–2018 Drought in Northeast Brazil

“…The univariate approach to calculate the drought return period has traditionally dominated the drought frequency analysis and it is a common practice in Brazil [2,5,6,10,72,77]. Martins et al [10] estimated the return period of the 2012-2016 drought that occurred on the most significant water system in NEB, São Francisco River Basin, as 135 years using the univariate approach.…”

Examining the influence of river–lake interaction on the drought and water resources in the Poyang Lake basin

“…Numerous drought indices have been developed to monitor droughts (Rossi et al, 2007), including the worldwide used indices of the Standardized Precipitation Index (SPI, e.g. Mckee et al, 1993;Zhang et al, 2012;Portela et al, 2015), the Normalised Flow Index (NFI, e.g. Gosling, 2014), the Reconnaissance Drought Index (RDI, e.g.…”

Comprehensive Characterization of Droughts in Slovakia

“…For this purpose a kernel occurrence rate estimator (KORE) was applied to the historical temporal series of drought occurrences [24]- [27]. Only severe or worse droughts, represented by SPI3 values lower than -1.28, were considered.…”

“…A Gaussian kernel was adopted [29]. The KORE analysis used the methodology detailed by [25]- [27] applied to the RPCs obtained from the SPI3 field. To reduce the boundary estimation bias, pseudo data was generated before and after the observation period.…”