Application of Multivariate Approach in the Analysis of Hydrological Phenomena (Case Study: Flood in Boustan Dam Watershed of Golestan Province)

Peak, volume, and duration are the main characteristics of a flood. Therefore, in designing hydraulic structures, the frequency analysis of flood should be done considering the multivariate point of view in order to decrease the flood damage. Since the interaction of dependent variables is not considered in the univariate frequency analysis, it can lead to underestimating or overestimating the magnitude of a certain event. Copula is a powerful tool, which has the capability and efficiency required for concurrent analysis of behavior of the variables and the correlation among them. This research emphasizes the necessity of bivariate analysis of flood in designing the hydrological structures and decreasing the flood damage. Therefore, copula functions were used for bivariate frequency analysis of flood (discharge and volume).