Application of Regional Frequency Analysis for Identification of Homogeneous Regions of Design Wave Conditions Offshore Portugal

2011 ◽  
Author(s):  
Cla´udia Lucas ◽  
G. Muraleedharan ◽  
C. Guedes Soares
Keyword(s):  
Frequency Analysis ◽  
Regional Frequency Analysis ◽  
Daily Maximum ◽  
Significant Wave ◽  
Extreme Quantiles ◽  
Wave Heights ◽  
Significant Wave Heights ◽  
Grid Points ◽  
Homogeneous Regions ◽  
Regional Frequency

Regional frequency analysis (RFA) based on L-moments is applied to the HIPOCAS hindcast data using daily maximum significant wave heights offshore Portugal to identify the homogeneous regions and to suggest the appropriate regional frequency distribution and extreme quantiles. Several statistics are computed at the various grid points in the area of study to classify the wave conditions of the regions. The daily maximum significant wave heights of the rough winter month January are used for this case study. The results of the study have shown that there are 3 homogeneous regions in the offshore region under investigation (35°–45°N, −9.5°–−11°W) comprising from 15 equally spaced grid points referring to an area of 0.25°×0.25°. It is interesting to observe that the algorithm is able to identify neighboring grid points as members of different regions. The maximum discrepancy between the at-sites’ extreme quantiles and their respective regional quantiles is 0.82 m for a return period of 100 years.

scholarly journals Comparative Study of Regional Frequency Analysis and Traditional At-Site Hydrological Frequency Analysis

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 486
Author(s):  
Mengrui Li ◽  
Xiaodong Li ◽  
Tianqi Ao
Keyword(s):  
Frequency Analysis ◽  
Return Period ◽  
Flood Control ◽  
Regional Frequency Analysis ◽  
Optimal Frequency ◽  
Frequency Curve ◽  
Design Values ◽  
Homogeneous Regions ◽  
Regional Frequency ◽  
Hydrological Frequency Analysis

Hydrological frequency analysis plays an indispensable role in the construction of national flood control projects. This study selects the stations with the smallest and largest discordances in the nine homogeneous regions of Sichuan Province as the representative stations, and results obtained by regional frequency analysis are compared with those obtained by traditional at-site hydrological frequency analysis. The results showed that the optimal frequency distribution of each representative station obtained by traditional at-site hydrological frequency analysis and the ones of corresponding homogeneous regions obtained by regional frequency analysis were not necessarily consistent, which was related to the site and homogeneous regions. At the same time, there were also differences between the fitting of the theoretical rainstorm frequency curve obtained by the two methods and the observation. In general, in each homogeneous region, the results obtained by regional frequency analysis and traditional at-site hydrological frequency analysis at the stations with the largest frequency analysis were quite different. The design values obtained by the two methods were also increasingly different with the increase of the return period. The study has specific reflections on the differences between regional frequency analysis and traditional at-site hydrological frequency analysis.

Estimating Extreme Waves in Brazil Using Regional Frequency Analysis

2016 ◽  
Author(s):  
Ricardo M. Campos ◽  
C. Guedes Soares
Keyword(s):  
Frequency Analysis ◽  
Grid Point ◽  
Quantile Function ◽  
Regional Frequency Analysis ◽  
Southeastern Brazil ◽  
Significant Wave ◽  
Test Of Hypothesis ◽  
L Moments ◽  
Using Data ◽  
Regional Frequency

Regional Frequency Analysis (RFA) based on L-moments is used to calculate spatial extreme return values of significant wave height. The RFA consists of using data from different sites with similar statistical characterisation to better estimate quantile functions, which can be used for regional or site-specific analyses. This technique is applied to a selected area in the South Atlantic Ocean (Brazil) using a group of wave hindcasts produced by a simulation with WAVEWATCH III model. The statistical approach of RFA is divided into four steps: (1) First inspection of the data; (2) Regionalization and definitions of statistically homogeneous sub-regions; (3) choice of Probabilistic Distribution and test of hypothesis; (4) Calculation of L-moments and final regional quantile function. The results of RFA are reliable extreme return values at each grid point with very low variance of the distribution parameters estimators and narrow confidence intervals. Considering the return period of 100 years, the significant wave heights vary from 5.5 to 11.2 meters within the considered domain in southern and southeastern Brazil.

scholarly journals ASSESSMENT OF THE REGIONAL FREQUENCY ANALYSIS TO THE ESTIMATION OF EXTREME STORM SURGES

2012 ◽  
Vol 1 (33) ◽  
pp. 27 ◽  
Author(s):  
Jérôme Weiss ◽  
Pietro Bernardara ◽  
Michel Benoit
Keyword(s):  
Frequency Analysis ◽  
Storm Surges ◽  
Regional Frequency Analysis ◽  
Dependence Structure ◽  
The North ◽  
Extreme Storm ◽  
Physically Based ◽  
Pairwise Dependence ◽  
Homogeneous Regions ◽  
Regional Frequency

Regional frequency analysis (RFA) is performed to estimate extreme storm surges along the French coasts of the Atlantic Ocean, the English Channel and the Southern part of the North Sea. An insight on the formation of physically homogeneous regions from a criterion of propagation of storms is provided. The treatment of the pairwise dependence structure within a given region through a spatial extreme value copula is also considered, leading to a model coupling physically-based RFA and spatial dependence to describe the probabilistic behavior of extreme storm surges.

scholarly journals Hybrid Approach to Delineation of Homogeneous Regions for Regional Precipitation Frequency Analysis

2009 ◽  
Vol 57 (4) ◽  
pp. 226-249 ◽  
Author(s):  
Ladislav Gaál ◽  
Ján Szolgay ◽  
Milan Lapin ◽  
Pavol Faško
Keyword(s):  
Distribution Function ◽  
Frequency Analysis ◽  
Regional Distribution ◽  
Hybrid Approach ◽  
Heavy Precipitation ◽  
Regional Frequency Analysis ◽  
Precipitation Frequency ◽  
Precipitation Analysis ◽  
Homogeneous Regions ◽  
Regional Frequency

Hybrid Approach to Delineation of Homogeneous Regions for Regional Precipitation Frequency AnalysisRegional frequency analysis of heavy precipitation amounts based on the estimation of the parameters of a regional distribution function usingL-moments is adopted for the specific geographical-climatological settings of Slovakia. The paper focuses on the first step of the regionalL-moment algorithm (Hosking, Wallis, 1997), which is the delineation of homogeneous regions. Objective and process-based logical pooling techniques are used to form homogeneous pooling groups of rainfall gauging stations for regional frequency analysis ofk-day precipitation amounts (k= 1 to 5 days). Even though the delineation of homo-geneous regions by means of objective methods is generally accepted and recommended in the literature, it is concluded here that such a pooling of similar sites should not be carried out automatically in precipitation analysis. Instead, a combination of physical/geomorphological considerations and objective methods should be preferred.

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