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

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 834 ◽  
Author(s):  
João Dehon Pontes Filho ◽  
Francisco de Assis Souza Filho ◽  
Eduardo Sávio Passos Rodrigues Martins ◽  
Ticiana Marinho de Carvalho Studart
Keyword(s):  
Impact Analysis ◽  
Extreme Event ◽  
Northeast Brazil ◽  
Copula Functions ◽  
Drought Duration ◽  
The Pacific ◽  
Prone Area ◽  
Drought Duration And Severity ◽  
Region Scale ◽  
Hydrographic Regions

The 2012–2018 drought was such an extreme event in the drought-prone area of Northeast Brazil that it triggered a discussion about proactive drought management. This paper aims at understanding the causes and consequences of this event and analyzes its frequency. A consecutive sequence of sea surface temperature anomalies in the Pacific and Atlantic Oceans, at both the decadal and interannual scales, led to this severe and persistent drought. Drought duration and severity were analyzed using run theory at the hydrographic region scale as decision-makers understand impact analysis better at this scale. Copula functions were used to properly model drought joint characteristics as they presented different marginal distributions and an asymmetric behavior. The 2012–2018 drought in Ceará State had the highest mean bivariate return period ever recorded, estimated at 240 years. Considering drought duration and severity simultaneously at the level of the hydrographic regions improves risk assessment. This result advances our understanding of exceptional events. In this sense, the present work proposes the use of this analysis as a tool for proactive drought planning.

scholarly journals Drought Risk Analysis in the Eastern Cape Province of South Africa: The Copula Lens

Water ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1938 ◽  
Author(s):  
Christina M. Botai ◽  
Joel O. Botai ◽  
Abiodun M. Adeola ◽  
Jaco P. de Wit ◽  
Katlego P. Ncongwane ◽  
...  
Keyword(s):  
South Africa ◽  
Gaussian Copula ◽  
Dependence Structure ◽  
Drought Risk ◽  
Eastern Cape Province ◽  
Return Periods ◽  
Eastern Cape ◽  
Copula Functions ◽  
Drought Duration ◽  
Drought Duration And Severity

This research study was carried out to investigate the characteristics of drought based on the joint distribution of two dependent variables, the duration and severity, in the Eastern Cape Province, South Africa. The drought variables were computed from the Standardized Precipitation Index for 6- and 12-month accumulation period (hereafter SPI-6 and SPI-12) time series calculated from the monthly rainfall data spanning the last five decades. In this context, the characteristics of climatological drought duration and severity were based on multivariate copula analysis. Five copula functions (from the Archimedean and Elliptical families) were selected and fitted to the drought duration and severity series in order to assess the dependency measure of the two variables. In addition, Joe and Gaussian copula functions were considered and fitted to the drought duration and severity to assess the joint return periods for the dual and cooperative cases. The results indicate that the dependency measure of drought duration and severity are best described by Tawn copula families. The dependence structure results suggest that the study area exhibited low probability of drought duration and high probability of drought severity. Furthermore, the multivariate return period for the dual case is found to be always longer across all the selected univariate return periods. Based on multivariate analysis, the study area (particularly Buffalo City, OR Tambo and Alfred Zoo regions) is determined to have higher/lower risks in terms of the conjunctive/cooperative multivariate drought risk (copula) probability index. The results of the present study could contribute towards policy and decision making through e.g., formulation of the forward-looking contingent plans for sustainable management of water resources and the consequent applications in the preparedness for and adaptation to the drought risks in the water-linked sectors of the economy.

scholarly journals Copula-Based Drought Monitoring and Assessment According to Zonal and Meridional Temperature Gradients

Atmosphere ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1066
Author(s):  
Abudureymjang Otkur ◽  
Dian Wu ◽  
Yin Zheng ◽  
Jong-Suk Kim ◽  
Joo-Heon Lee
Keyword(s):  
Kendall Test ◽  
Accurate Method ◽  
Copula Function ◽  
Temperature Gradients ◽  
Drought Severity ◽  
Copula Functions ◽  
Drought Duration ◽  
Drought Assessment ◽  
Drought Characteristics ◽  
Drought Duration And Severity

Drought is one of the most severe natural disasters. However, many of its characteristic variables have complex nonlinear relationships. Therefore, it is difficult to construct effective drought assessment models. In this study, we analyzed regional drought characteristics in China to identify their relationship with changes in meridional and zonal temperature gradients. Drought duration and severity were extracted according to standardized precipitation evapotranspiration index (SPEI) drought grades. Trends in drought duration and severity were detected by the Mann-Kendall test for the period of 1979–2019; they showed that both parameters had been steadily increasing during that time. Nevertheless, the increasing trend in drought severity was particularly significant for northwest and southwest China. A composite analysis confirmed the relationships between drought characteristics and temperature gradients. The northwest areas were relatively less affected by temperature gradients, as they are landlocked, remote from the ocean, and only slightly influenced by the land–ocean thermal contrast (LOC) and the meridional temperature gradient (MTG). The impacts of LOC and MTG on drought duration and severity were positive in the southwest region of China but negative in the northeast. As there was a strong correlation between drought duration and severity, we constructed a 2D copula function model of these parameters. The Gaussian, HuslerReiss, and Frank copula functions were the most appropriate distributions for the northeast, northwest, and southwest regions, respectively. As drought processes are highly complex, the present study explored the internal connections between drought duration and severity and their responses to meteorological conditions. In this manner, an accurate method of predicting future drought events was developed.

scholarly journals Analyzing the duration frequency and severity of drought using copula function in the Yazd city

2021 ◽  
Author(s):  
Mehrtash EskandariPour ◽  
Shahrokh Soltaninia
Keyword(s):  
Distribution Function ◽  
Frequency Analysis ◽  
Return Period ◽  
Copula Function ◽  
Copula Functions ◽  
Drought Duration ◽  
Drought Analysis ◽  
Drought Duration And Severity ◽  
Bivariate Frequency Analysis ◽  
Yazd City

Abstract Duration and severity are the two main variables used in drought analysis. The copula functions are appropriate for multivariate drought analysis, as it lacks the limitations of the classical multivariate distribution function. This study investigated the bivariate frequency analysis of drought duration and severity of Yazd city in Iran synoptic station during 1953–2013. To this end, first, the drought duration and severity variables were derived from the 6-month Standardized Precipitation Index. Then, considering the distribution functions, the gamma distribution function was selected for analyzing the severity and the exponential distribution function was selected for analyzing the duration and then the Clayton copula function was selected out of the three copula functions as the most appropriate one. After conducting bivariate frequency analysis, the joint seasonal and conjunctive return period and conditional return period curves were plotted. The current study well signified that multivariate analyses could present better interpretations of the reality; for example, as it was identified in conditional return period curves of the drought, for every constant duration, the amount of the return period changed as the severity changed. On the contrary, in analyzing the univariate of duration, no effects of severity were observed.

Modeling drought duration and severity using two-dimensional copula

2021 ◽  
Vol 214 ◽  
pp. 105530
Author(s):  
Muhammad Asif Khan ◽  
Muhammad Faisal ◽  
Muhammad Zaffar Hashmi ◽  
Amna Nazeer ◽  
Zulfiqar Ali ◽  
...  
Keyword(s):  
Two Dimensional ◽  
Drought Duration ◽  
Drought Duration And Severity

EDUKASI DAN MITIGASI GEMPA PADA BANGUNAN

2021 ◽  
pp. 417
Author(s):  
Daniel Christianto ◽  
Sunarjo Leman ◽  
Alvira Nathania Tanika ◽  
Maria Kevinia Sutanto ◽  
Vryscilia Marcella
Keyword(s):  
General Information ◽  
Physical Contact ◽  
Eurasian Plate ◽  
Earthquake Mitigation ◽  
Natural Event ◽  
Australian Plate ◽  
The Pacific ◽  
Prone Area ◽  
Tectonic Earthquakes ◽  
The Impact

A natural disaster is a natural event that has a major impact on the human population. One of the natural events that became the focus of this PKM activity was an earthquake. Earthquakes are natural events in the form of vibrations or wavy movements on the earth's crust caused by internal forces. Earthquakes caused by shifting of the ground are called tectonic earthquakes and earthquakes caused by volcanoes are called volcanic earthquakes. Indonesia is an earthquake-prone area because it is located on three plates, namely the Eurasian Plate, the Pacific Plate, and the Indo-Australian Plate. Only in western, central and southern Kalimantan, the source of the earthquake was not found. To reduce the impact of risk during an earthquake, it is necessary to carry out an earthquake mitigation to the community in areas prone to earthquakes. Earthquake mitigation that will be carried out in this PKM activity is in the form of counseling through online webinars to prevent physical contact or crowds, related to the Covid19 pandemic. As a result, from the questions asked by participants, there is still a lack of understanding of the dangers of changing the function of the building or the building's use limit based on the design load and the condition of the building after the earthquake. So for the next PKM, it is recommended to make general information guidelines such as examples of photos or pictures about the condition of buildings that need to be reviewed for repairs or are no longer suitable for use after being hit by an earthquake.Bencana alam adalah suatu peristiwa alam yang mengakibatkan dampak besar bagi populasi manusia. Salah satu peristiwa alam yang menjadi fokus dalam kegiatan PKM ini adalah gempa bumi. Gempa bumi merupakan fenomena alam berupa getaran atau gerakan bergelombang pada lempeng bumi yang disebabkan oleh tenaga yang berasaldari dalam bumi. Gempa yang disebabkan oleh pergeseran tanah dinamakan gempa tektonik dan gempa yang disebabkan oleh gunung berapi dinamakan gempa vulkanik. Indonesia merupakan daerah rawan gempa karena terletak di atas tiga lempeng yakni Lempeng Eurasia, Lempeng Pasifik, dan Lempeng Indo-Australia. Hanya di Kalimantan bagian barat, tengah, dan selatan, sumber gempa bumi tidak ditemukan. Untuk mengurangi dampak resiko pada saat gempa perlu dilakukan suatu mitigasi gempa kepada masyarakat di daerah yang rawan terjadi gempa bumi. Mitigasi gempa yang akan dilakukan dalam kegiatan PKM ini berupa penyuluhan melalui webinar secara online untuk mencegah kontak fisik atau kerumunan, berhubungan dengan pandemi Covid19. Hasilnya, dari pertanyaan yang diajukan peserta, masih kurang pemahaman bahaya dari mengubah fungsi guna bangunan atau batas guna bangunan berdasarkan beban desain dan kondisi bangunan setelah gempa. Maka untuk PKM selanjutnya, disarankan membuat panduan informasi secara umum seperti contoh foto atau gambar tentang kondisi bangunan yang perlu ditinjau untuk perbaikan atau tidak layak guna lagi setelah terkena gempa.

scholarly journals Estudos de Variabilidades Interanuais e Interdecenais da Precipitação Pluvial das Regiões Hidrográficas Tocantins-Araguaia e São Francisco no Brasil

2021 ◽  
Vol 14 (2) ◽  
pp. 1116
Author(s):  
José Nildo da Nóbrega ◽  
Carlos Antonio Costa dos Santos ◽  
Francisco de Assis Salviano de Sousa ◽  
Bergson Guedes Bezerra ◽  
Geber Barbosa de Albuquerque Moura ◽  
...  
Keyword(s):  
Wavelet Transform ◽  
Geographical Area ◽  
Monthly Data ◽  
The Pacific ◽  
Cross Wavelet Transform ◽  
Wavelet Transform Analysis ◽  
The Cross ◽  
Hydrographic Regions ◽  
Cross Wavelet ◽  
Phase Differences

O objetivo é investigar as fases temporais das variabilidades de precipitação pluvial das Regiões Hidrográficas do Tocantins-Araguaia e São Francisco, como, também, correlacioná-las com índices de anomalias de Temperatura da Superfície do Mar (TSM) do Pacífico, na região do Niño 3.4, utilizando a análise de transformada ondaleta. A área geográfica está localizada entre os paralelos 0,5º S a 20º S e meridianos 34,8º W a 55,4º W. Foram utilizados dados mensais de precipitação observados e de reanálise (1º x 1º), no período de 1945-2016, e de TSM de 1950-2016 provenientes de órgãos governamentais nacionais e internacionais. As Ondaletas Contínuas mostraram que as variabilidades dominantes, de precipitação total anual, nas Regiões Hidrográficas do Tocantins-Araguaia e do São Francisco são nas escalas de três a cinco anos, de 11 a 12 anos e em torno de 22 anos. Para ambas as Regiões essas frequências estão em fases, pela Transformada Ondaleta Cruzada e confirmada pela Ondaleta Coerente. Nas análises de Ondaletas Cruzada e Coerente das precipitações com os índices oceânicos se verificou que houve avanço (135º) na série do Niño 3.4 em relação as das precipitações das Regiões nas escalas de três a cinco anos, mas foram verificadas diferenças de fase nas escalas decenais da precipitação das Regiões com os índices oceânicos. Concluiu-se que as variabilidades da precipitação de ambas as Regiões estão em fase e que os eventos ENOS influenciam nas precipitações das Regiões Hidrográficas do Tocantins-Araguaia e São Francisco.  Studies of Interannual and Interdecennial Variabiliteis of Rainfall in the Tocantins-Araguaia and São Francisco Hydrographic Regions in Brazil ABSTRACTThe objective is to investigate the temporal phases of the variability of rainfall in the Hydrographic Regions of Tocantins-Araguaia and São Francisco, as well as to correlate them with anomalies indexes of the Sea Surface Temperature (SST) of the Pacific, in the Niño 3.4 region, using wavelet transform analysis. The geographical area is located between the parallels 0.5º S to 20º S and meridians 34.8º W to 55.4º W. We used monthly data of observed and reanalysis precipitation (1º x 1º), in the period from 1945 to 2016, and from 1950 to 2016 for SST. The data are from national and international government agencies. The continuous wavelet showed that the dominant variability of total annual precipitation, in the Hydrographic Regions of Tocantins-Araguaia and São Francisco, are in the frequencies of three to five years, 11 to 12 years and about 22 years. These frequencies are in phases by the cross wavelet transform and confirmed by the coherent wavelet. In the cross and coherent wavelet analysis of the precipitation with the oceanic indices, there was an advance (135º) in the Niño 3.4 series in relation to the precipitation of the Regions in the frequency of three to five years, but phase differences were observed in the decadal frequencies between the precipitation of the Regions and oceanic indices. We concluded that the variability of precipitation in both regions is in phase and that the ENOS events influence the rainfall in the Hydrographic Regions of Tocantins-Araguaia and São Francisco.Keywords: El Niño, hydrographic catchment, wavelet, climate variability.

Richness and composition of the Cladocera community (Crustacea: Branchiopoda) from the Maranhão State, Northeast Brazil

Zootaxa ◽  
2021 ◽  
Vol 5081 (3) ◽  
pp. 420-432
Author(s):  
ARIELLY S. SANTOS ◽  
FRANCISCO DIOGO R. SOUSA ◽  
LOURDES M. A. ELMOOR-LOUREIRO ◽  
DANIEL S. ANDRADE ◽  
RICCARDO MUGNAI
Keyword(s):  
New Species ◽  
New Record ◽  
The State ◽  
Water Bodies ◽  
Northeast Brazil ◽  
Hydrographic Regions

The state of Maranhão, northeast Brazil, has four different biomes. The water bodies in Maranhão belongs to three hydrographic regions. Thus, the state potentially contributes to a high biodiversity. Despite that, in the state, the study of cladocerans can still be considered incipient. This work aims to summarize the list of species of cladocerans in the state of Maranhão, including the results of new fauna surveys. We report ten new species records for the state, two species represent the new record of the genus Pseudosida Herrick, 1884. The results found point to the occurrence of 82 valid taxa in the state of Maranhão.  

scholarly journals Hydrological Drought Regimes of the Huai River Basin, China: Probabilistic Behavior, Causes and Implications

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2390 ◽  
Author(s):  
Sun ◽  
Zhang ◽  
Yao ◽  
Wen
Keyword(s):  
River Basin ◽  
Hydrological Drought ◽  
Drought Severity ◽  
Copula Functions ◽  
Drought Duration ◽  
Huai River Basin ◽  
Huai River ◽  
The Impact ◽  
Hydrological Droughts ◽  
The Huai River Basin

: Hydrological droughts were characterized using the run-length theory and the AIC (Akaike information criterion) techniques were accepted to evaluate the modeling performance of nine probability functions. In addition, the copula functions were used to describe joint probability behaviors of drought duration and drought severity for the major tributaries of the Huai River Basin (HRB) which is located in the transitional zone between humid and semi-humid climates. The results indicated that: (1) the frequency of hydrological droughts in the upper HRB is higher than that in the central HRB, while the duration of the hydrological drought is in reverse spatial pattern. The drought frequency across the Shiguan River along the south bank of the HRB is higher than the other two tributaries; (2) generalized Pareto distribution is the appropriate distribution function with the best performance in modelling the drought duration over the HRB; while the Generalized Extreme Value (GEV) distribution can effectively describe the probabilistic properties of the drought severity. Joe copula and Tawn copula functions are the best choices and were used in this study. Given return periods of droughts of <30 years, the droughts in the upper HRB are the longest, and the shortest are in the central HRB; (3) the frequency of droughts along the mainstream of the HRB is higher than tributaries of the HRB. However, concurrence probability of droughts along the mainstream of the HRB is lower than the tributaries of the HRB. The drought resistance capacity of HRB has been significantly improved, effectively reducing the impact of hydrological drought on crops after 2010.

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