Abstract
Regional flood frequency analysis (RFFA) is the major instrument for studying of the flood regime at locations where little or no information is available. Outliers have an important effect on the flood frequency analysis and the existence of them in hydrologic data sets affects the regional flood frequency analysis. Outlier analysis is composed of two steps, outlier detection and outlier treatment. After detecting outlier, one should determine how to deal with it. This has the particular role in outlier analysis. In this research, flood frequency analysis was done for the Dez River basin located in south-western Iran. First of all, the studied basin was separated in two hydrological homogeneous regions according their physiographical, climatic and vegetation characteristics. Then, outliers were detected in each region by using Principal component analysis method (PCA). We considered two approaches to survey and compare the effect of the outliers in RFFA. In the first approach outliers were retained, while in the second approach frequency analysis was done after removal the years which contain outliers. Result of RFFA via L-moment method showed that the estimated quantiles in two approaches, particularly in highly return period have a lot of difference. These results illustrate that dealing with the outliers in flood frequency analysis is of the special importance.
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References
Barnett, V. and Lewis, T., Outliers in Statistical Data, Chichester, N.Y.: John Wiley, 1978, 3rd edition.
Cunnane, C., Review of statistical methods for flood frequency estimation, in Hydrologic Frequency Modeling, Singh, V.P., Ed., 1987, pp. 49–95.
Dalrymple, T., Flood frequency analysis, US Geol. Survey Water Supply Paper, 1960, 543A.
Dixon, W.J., Analysis of extreme values, Annals Math. Statistics, 1950, vol. 21, pp. 488–506.
Grubbs, F.E. and Beck, G., Extension of sample sizes and percentage points for significance tests of outlying observations, Technometrics, 1972, vol. 4, no. 14, pp. 847–853.
Hosking, J.R.M. and Wallis, J.R., Some statistics useful in regional frequency analysis, J. Water Resour. Res., 1993, vol. 20, pp. 271–281.
Hosking, J.K.M. and Wallis, J.R., Regional frequency analysis, an approach based on L-moments, Cambridge Univ. Press, 1997.
Iglewicz, B. and Hoaglin, D.C., How to detect and handle outliers, American Soc. for Quality, Milwaukee, WI, 1993.
Jackson, D. and Chen, Y., Robust principal component analysis and outlier detection with ecological data, Environ., 2004, vol. 15, pp. 129–139.
Jackson, J.E., Quality control methods for several related variables, Technometrics, 1959, vol. 1, pp. 359–377.
Johnson, R.A. and Wichern, D.W., Applied Multivariate Statistical Analysis, Englewood Cliffs, USA: Prentice-Hall Inc., 1982.
Kottegoda, N.T., Investigation of outliers in annual maximum flow series, J. Hydrol., 1984, vol. 72, nos. 1–2, pp. 105–137.
Kumar, R., Chatterjee, C., Kumar, S., Lohani, A.K., and Singh, R.D., Development of regional flood frequency relationships using L-moments for middle Ganga plains subzone 1(f) of India, Water Resour. Management, 2003, vol. 17, pp. 243–257.
Mahalanobis, P.C., On the generalized distance in statistics, Proc. National Inst. Sci. India, 1936, vol. 2, no. 1, pp. 49–55.
Martel, B., Quadra, T.B.M.J., Barbet, M., Bruneau, P., Latraverse, M., and Kamali Nazhad, M., Regional frequency analysis of autumnal floods in the province of Quebec, Canada, Nat Hazards, 2011, vol. 59, pp. 681–698.
Pearson, C.P., New Zealand regional flood frequency analysis using L-moments, J. Hydrol., 1991, vol. 30, no. 2, pp. 53–63.
Rousseeuw, P.J. and Leroy, A.M., Robust Regression and Outlier Detection, N.Y.: John Wiley and Sons, 1987.
Siyi, Hu., Problem with outliers test methods in flood frequency analysis, J. Hydrol., 1987, vol. 96, pp. 375–383.
Spencer, C.S. and McCuen, R.H., Detection of outliers in pearson type iii data, J. Hydrol. Eng., vol. 1, pp. 2–10, 1996.
Wallis, J.R., Regional frequency studies using L-moments, IBM Res. Rep., 1989, p. 17.
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Sarraf, A.P. Flood outlier detection using PCA and effect of how to deal with them in regional flood frequency analysis via L-moment method. Water Resour 42, 448–459 (2015). https://doi.org/10.1134/S0097807815040132
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DOI: https://doi.org/10.1134/S0097807815040132