Regional flood frequency analysis using physiographical space based interpolation technique in basins of Mazandaran province

Document Type : Research

Authors

1 Master's student of desertification at Zabul University

2 Assistant Professor of the Faculty of Natural Resources of Zabul University

3 Master's degree in water engineering

Abstract

Advances in tools and spatial and temporal techniques, have provided new approaches in regional flood analysis and parameters estimation. Application of interpolation techniques based on physiographical attributes, seems to be new in many hydrological aspects. However, the hydrological, climatological and physiographical information of 38 river basin information of watersheds inside of Mazandaran province were obtained and regional flood estimates basis the main and specific quantiles discharge and several of return periods were estimated using physiographical space based interpolation technique. The Multivariate Principal Component Analysis was used to design physiographic space using the six geomorphoclimatical variables affecting the flood. The exponential model had the best fit to smi-varigram model in all return periods and the ordinary kriging, simple kriging and IDW methods were used for interpolation. Results evaluated using Jack knife mutual procedure and the four statistical indexes including BIASr, RMSE, RMSEr, and NASH. Results improved dramatically, when the data of 7 stations eliminated due to having the largest value of RMSEr and BIASr. Accordingly, in the first case the NASH values increased from 0.4 to 0.6 up to 0.5 to 0.8, respectively. Moreover, the three other indexes led to satisfying results, too. This implies that the proposed approach has the efficiency to estimate discharge in ungauged watersheds. Results of the interpolation indicated that the ordinary kriging and IDW have similar performances and their performances are better than simple kriging.

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