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.

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 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 A Bivariate Frequency Analysis of Extreme Wave Heights and Periods Using a Copula Function in South Korea

2018 ◽  
Vol 85 ◽  
pp. 566-570
Author(s):  
Yong-Tak Kim ◽  
Jong-Hyeon Park ◽  
Byoung-Han Choi ◽  
Dong Ho Kim ◽  
Hyun-Han Kwon
Keyword(s):  
South Korea ◽  
Frequency Analysis ◽  
Copula Function ◽  
Extreme Wave ◽  
Wave Heights ◽  
Bivariate Frequency Analysis

scholarly journals Comparison Between Bivariate and Trivariate Flood Frequency Analysis Using the Archimedean Copula Functions, A Case Study of the Karun River in Iran

2021 ◽  
Author(s):  
Mohamad Haytham Klaho ◽  
Hamid R. Safavi ◽  
Mohamad H. Golmohammadi ◽  
Maamoun Alkntar
Keyword(s):  
Frequency Analysis ◽  
Return Period ◽  
Goodness Of Fit ◽  
Flood Frequency ◽  
Archimedean Copula ◽  
Flood Frequency Analysis ◽  
Cumulative Probability ◽  
Copula Functions ◽  
Flood Peak ◽  
Multiple Variables

Abstract Historically, severe floods have caused great human and financial losses. Therefore, the flood frequency analysis based on the flood multiple variables including flood peak, volume and duration poses more motivation for hydrologists to study. In this paper, the bivariate and trivariate flood frequency analysis and modeling using Archimedean copula functions is focused. For this purpose, the annual flood data over a 55-year historical period recorded at the Dez Dam hydrometric station were used. The results showed that based on goodness of fit criteria, the Frank function built upon the couple of the flood peak-volume and the couple of the flood peak-duration as well as the Clayton function built upon the flood volume-duration were identified to be the best copula families to be adopted. The trivariate analysis was conducted and the Clayton family was chosen as the best copula function. Thereafter, the common and conditional cumulative probability distribution functions were built and analyzed to determine the periodic "and", "or" and "conditional" bivariate and trivariate flood return periods. The results suggest that the bivariate conditional return period obtained for short-term periods is more reliable than the trivariate conditional return period. Additionally, the trivariate conditional return period calculated for long-term periods is more reliable than the bivariate conditional return period.

scholarly journals Drought Analysis in East Nusa Tenggara (Indonesia) Using Regional Frequency Analysis

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Heri Kuswanto ◽  
Anggi Wahyu Puspa ◽  
Imam Safawi Ahmad ◽  
Fausania Hibatullah
Keyword(s):  
Frequency Analysis ◽  
Return Period ◽  
Extreme Drought ◽  
Regional Frequency Analysis ◽  
Drought Risk ◽  
Drought Analysis ◽  
Daily Precipitation Data ◽  
Pearson Type ◽  
Normal Rainfall ◽  
Regional Frequency

Drought is a condition of a shortage of water that has an impact on economic activity. This research studies the severe drought area in Indonesia using Regional Frequency Analysis (RFA), based on daily precipitation data recorded at nine stations. The analysis reveals five homogeneous regions, based on discordancy and heterogeneity tests. Furthermore, the L-moment approach is applied to investigate the regional distribution and suggests that the Pearson type III distribution is the distribution that best fits the five regions. This distribution is also used to calculate the regional growth curve that is employed in the drought analysis. The drought return period analysis, for conditions of 40% of normal rainfall, concludes that the region containing the Fransiskus Xaverius, Gewayantana, and Mali stations has the highest drought risk, indicated by the fastest return period estimate of 2 years and 4 months. Moreover, the extreme drought analysis shows that two of the regions have the potential to experience the return of extreme drought, with less than 20% of normal rainfall, in less than four years.

Bivariate frequency analysis of low flow using copula functions (case study: Dez River Basin, Iran)

2018 ◽  
Vol 77 (18) ◽  
Author(s):  
Farshad Ahmadi ◽  
Feridon Radmaneh ◽  
Mohammad Reza Sharifi ◽  
Rasoul Mirabbasi
Keyword(s):  
River Basin ◽  
Frequency Analysis ◽  
Low Flow ◽  
Copula Functions ◽  
Bivariate Frequency Analysis

scholarly journals Analysis and Application of Drought Characteristics Based on Theory of Runs and Copulas in Yunnan, Southwest China

2020 ◽  
Vol 17 (13) ◽  
pp. 4654
Author(s):  
Liping Wang ◽  
Xingnan Zhang ◽  
Shufang Wang ◽  
Mohamed Khaled Salahou ◽  
Yuanhao Fang
Keyword(s):  
Short Duration ◽  
Return Period ◽  
Joint Distribution ◽  
Yunnan Province ◽  
Cumulative Probability ◽  
Drought Duration ◽  
Drought Characteristics ◽  
Joint Return ◽  
Drought Duration And Severity ◽  
Drought Characteristic

Drought is a complex natural disaster phenomenon. It is of great significance to analyze the occurrence and development of drought events for drought prevention. In this study, two drought characteristic variables (the drought duration and severity) were extracted by using the Theory of Runs based on four drought indexes (i.e., the percentage of precipitation anomaly, the standardized precipitation index, the standardized precipitation evapotranspiration index and the improved comprehensive meteorological drought index). The joint distribution model of drought characteristic variables was built based on four types of Archimedean copulas. The joint cumulative probability and the joint return period of drought events were analyzed and the relationship between the drought characteristics and the actual crop drought reduction area was also studied. The results showed that: (1) The area of the slight drought and the extreme drought were both the zonal increasing distribution from northeast to southwest in Yunnan Province from 1960 to 2015. The area of the high frequency middle drought was mainly distributed in Huize and Zhanyi in Northeast Yunnan, Kunming in Central Yunnan and some areas of Southwest Yunnan, whereas the severe drought was mainly occurred in Deqin, Gongshan and Zhongdian in Northwest Yunnan; (2) The drought duration and severity were fitted the Weibull and Gamma distribution, respectively and the Frank copula function was the optimal joint distribution function. The Drought events were mostly short duration and high severity, long duration and low severity and short duration and low severity. The joint cumulative probability and joint return period were increased with the increase of drought duration and severity; (3) The error range between the theoretical return period and the actual was 0.1–0.4 a. The year of the agricultural disaster can be accurately reflected by the combined return period in Yunnan Province. The research can provide guidelines for the agricultural management in the drought area.

Spatial characterization of drought events using synthetic hydrology

1996 ◽  
Vol 23 (6) ◽  
pp. 1231-1240 ◽  
Author(s):  
Donald H. Burn ◽  
William J. DeWit
Keyword(s):  
Power Generation ◽  
Frequency Analysis ◽  
Return Period ◽  
Hydroelectric Power ◽  
Drought Analysis ◽  
Generation Frequency ◽  
Spatial Characterization ◽  
Streamflow Generation

This paper describes an approach to spatial drought analysis based on multi-site streamflow synthesis. The approach developed can be used to assist with the quantification of the return period for the drought of record and can also be used to facilitate the identification of daesign drought events of a specified return period. The approach was applied to the Nelson–Churchill River basin in Manitoba, Canada. For this system, the impacts of droughts on power generation were investigated in addition to a determination of the return period for the drought of record. Key words: droughts, streamflow generation, frequency analysis, hydroelectric power.

scholarly journals Comparison of the Calculated Drought Return Periods Using Tri-variate and Bivariate Copula Functions under Climate Change Condition

2021 ◽  
Author(s):  
Elahe Motevali Bashi Naeini ◽  
Ali Mohammad Akhondali ◽  
Fereydoun Radmanesh ◽  
Jahangir Abedi-Koupai ◽  
Shahrokh Soltaninia
Keyword(s):  
Climate Change ◽  
Decisive Role ◽  
Copula Function ◽  
Drought Indices ◽  
Return Periods ◽  
Copula Functions ◽  
Drought Duration ◽  
Drought Characteristics ◽  
Primary Water ◽  
Bivariate Copula

Concerning the various effects of climate change on intensifying extreme weather phenomena all around the world, studying its possible consequences in the following years has attracted the attention of researchers. As the drought characteristics identified by drought indices are highly significant in investigating the possible future drought, the Copula function is employed in many studies. In this study, the two- and three-variable Copula functions were employed for calculating the return period of drought events for the historical, the near future, and the far future periods. The results of considering the two- and three-variable Copula functions were separately compared with the results of the calculated Due to the high correlation between drought characteristics, bivariate and trivariate of Copula functions were applied to evaluate the return periods of the drought. The most severe historical drought was selected as the benchmark, and the drought zoning map for the GCM models was drawn. The results showed that severe droughts can be experienced, especially in the upper area of the basin where the primary water resource is located. Also, the nature of the drought duration plays a decisive role in the results of calculating the return periods of drought events.

scholarly journals Comparison of the Calculated Drought Return Periods Using Tri-variate and Bivariate Copula Functions under Climate Change Condition

2021 ◽  
Author(s):  
Elaheh Motevalibashi Naeini ◽  
Ali Mohammad Akhoond-Ali ◽  
Fereydoun Radmanesh ◽  
Jahangir Abedi Koupai ◽  
Shahrokh Soltaninia
Keyword(s):  
Climate Change ◽  
Decisive Role ◽  
Copula Function ◽  
Drought Indices ◽  
Return Periods ◽  
Copula Functions ◽  
Drought Duration ◽  
Drought Characteristics ◽  
Primary Water ◽  
Bivariate Copula

Abstract Concerning the various effects of climate change on intensifying extreme weather phenomena all around the world, studying its possible consequences in the following years has attracted the attention of researchers. As the drought characteristics identified by drought indices are highly significant in investigating the possible future drought, the Copula function is employed in many studies. In this study, the two- and three-variable Copula functions were employed for calculating the return period of drought events for the historical, the near future, and the far future periods. The results of considering the two- and three-variable Copula functions were separately compared with the results of the calculated Due to the high correlation between drought characteristics, bivariate and trivariate of Copula functions were applied to evaluate the return periods of the drought. The most severe historical drought was selected as the benchmark, and the drought zoning map for the GCM models was drawn. The results showed that severe droughts can be experienced, especially in the upper area of the basin where the primary water resource is located. Also, the nature of the drought duration plays a decisive role in the results of calculating the return periods of drought events.

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