Document Type : Research Paper


1 PhD. of Watershed Managment, University of Yazd, Iran

2 Professor Assistant of Rangeland Management, Malayer University, Iran

3 Scientific member of Qazvin Natural Resources Research Center

4 Specialist of Qazvin regional water company


One of the important parameters in the design of flood control structures is to determine flood peak discharge for various return periods. A primary issue of planners in the face with flood is lack of data or insufficient data. One of the most reliable strategies is generalizing the results from sites with observed data to ungauged locations. The main goal of this study is regional flood frequency analysis using multiple regression method for Qazvin province of Iran. 8 out of 23 existing hydrometric station were removed because of the short-term statistics and construction of storage dam at upstream. The results of factor analysis showed that perimeter, equivalent diameter, time of concentration, length of main waterway and area were the main variables affecting flood magnitude. The remaining 15 stations were divided into two homogenous regions using cluster analysis. Homogeneity of these two regions was confirmed using homogeneity and heterogeneity tests of L-moments. Based on the best-fit criteria of Zdist, GNO distribution with the statistic of 0.29 has the best fit for the entire region but for one and two homogeneous regions, GLO and GPA distributions with the statistics equal to 0.09 & 1.56 have the best fit respectively. After calculating parameter values for selected distributions, discharges with different return periods were estimated for all stations. Then, regression relations were obtained between peak discharge and factors affecting flood peak for each return periods at two homogeneous regions. Peak discharges at ungauged locations can be estimated for different recurrence interval using these relationships.


[1] Eslamian, S. and Chavoshi Borujeni, S. (2004). Regional flood frequency analysis using L-Moments in central basins of Iran, Journal of Science and Technology of Agriculture and Natural Resources, Water and Soil Science, 7, 1-17.
[2] Greenwod, J.A., Landwehr, J.M., Matalas, N.C. and Wallis, J.R. (1979). Probability Weighted Moments: definition and relation to parameters of several distributions expressible in inverse form, Water Resources Research, 15, 1049-1054.
[3] Hosking, J.R.M. (1986). The Theory of Probability Weighted Moments, Reseach Report Rc12210, IBM Reseach, Yorktown Heights, New York.
[4] Hosking, J.R.M. (1990). L-Moments: Analysis and estimation of distributions using linear combinations of order statistics, Royal Statistical Society B, 52, 105-124.
[5] Hosking, J.R.M. and Wallis, J.R. (1993). Some statistical useful in regional frequency analysis, Water Resources Research, 29, 271-281.
[6] Lettenmaier, D.P., Wallis, J.R. and Wood, E.F. (1987). Effect of regional hetergenety an flood frequency estimation, Water Resources Research, 23, 313-323.
[7] Malekinezhad, H. (2007). Determination and evaluation of flood-probability relations using regression based techniques, 7th international seminar on river engineering, Shahid chamran university of Ahvaz, Iran.
[8] Malekinezhad, H., Nachtnebel, H.P. and Klik, A. (2011). Comparing the index-flood and multiple-regression methods using L-moments, Physics and Chemistry of the Earth, 36, 54-60.
[9] Modarres, R. and Soltani, S. (2007). Flood frequency analysis using L-moments, 7th international seminar on river engineering, Shahid chamran university of Ahvaz, Iran.
[10] Payravand, V., Salajegheh, A., Mahdavi, M. and Zare Chahouki, M.A. (2010). Comparison of regional flood analysis methods in central Alborz region, Journal of Range and watershed management, 63, 131-147.
[11] Pandey, G.R. and Nguyen, V.T.V. (1999). A comparative study of regression based methods in regional flood frequency analysis, Journal of Hydrology, 225, 92-101.
[12] Rahnama, M. and Rostami, R. (2007). Halil-River Basin Regional Flood Frequency Analysis Based on L-moment Approach, International Journal of Agricultural Research, 2, 261-267.
[13] Shamkoueyan, H., Ghahraman, B., Davary, K. and Sarmad, M. (2009). Flood frequency analysis using Linear moment and flood index method in Khorasan provinces, Journal of Water and Soil, 23, 31-43.
[14] Wallis, J.R., Matalas, N.C. and Slack, J.R. (1974). Just a moment!, Water Resources Research, 10, 211-219.