Please use this identifier to cite or link to this item: https://hdl.handle.net/11499/6480
Title: Assessment of the effects of discordant sites on regional flood frequency analysis
Authors: Saf, Betül
Keywords: Discordancy measure
Goodness-of-fit measure
L-moments
Regional frequency analysis
Regionalization
Flood estimation
Flood frequency analysis
Generalized extreme value distribution
Homogeneous regions
Hydrological data
Kappa distribution
Moment methods
Probability models
Regional analysis
Regional flood frequency analysis
River basins
Robust detection
Root mean square errors
Site identification
Sub-regions
Flood control
Floods
Method of moments
Regional planning
Simulators
Water resources
Probability distributions
data set
flood frequency
flooding
frequency analysis
numerical model
regionalization
water resource
Menderes Basin
Turkey
Abstract: Flood observations in hydrological data sets contain frequently outliers, and this causes problems for water resource researchers and planners if not addressed correctly. This study analyses how outliers affect the identification of regional probability distributions using L-moment methods. The main objective of the study is to assess the effect(s) of discordancy detection measures on regional flood probability types and the accuracy of the estimates based on the regional analysis. The classical and robust discordancy measures for discordant site identification are used to determine regional probability distributions in order to identify the effects of discordant sites on the regional probability distribution in a region of the Menderes River Basins in Turkey. The other objective is to show whether a probability model type and flood estimation based on the model is reliable if discordancy sites in the region are not detected. In the study, the homogeneity of the basin was tested using the L-moments based on the heterogeneity for two discordancy measures, assessed by carrying out 500 simulations using the four parameter Kappa distribution. Based on these tests, two sub-regions are defined, the Upper-Menderes and Lower-Menderes sub-regions, that have different numbers of sites for both discordancy measures. According to the L-moments goodness of statistic criteria, the generalized extreme value distribution was determined as the best-fit distribution for the Upper-Menderes and Lower-Menderes sub-regions based on the classical discordancy measure. The generalized extreme value distribution was also found to be the best-fit distribution for the Upper-Menderes sub-region for the robust discordancy measure, while the Pearson Type 3 distribution was the best for the Lower-Menderes sub-region based on the robust measure. To appraise the results for the sub-regions, the relative root mean square error and relative bias were employed. The results show that the homogeneous region determined from the robust discordancy measure is more accurate than the region identified using the classical robust measure. This means that the classical robust detection measure of flood frequency analysis needs to be improved. © 2009 Elsevier B.V. All rights reserved.
URI: https://hdl.handle.net/11499/6480
https://doi.org/10.1016/j.jhydrol.2009.11.011
ISSN: 0022-1694
Appears in Collections:Mühendislik Fakültesi Koleksiyonu
Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection

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