Peaks Over Threshold Model for Seasonal Flood Variations

by Taha B. M. J. Ouarda, Univ of Moncton, Moncton, Canada,
Fahim Ashkar, Univ of Moncton, Moncton, Canada,
Nassir El-Jabi, Univ of Moncton, Moncton, Canada,

Document Type: Proceeding Paper

Part of: Engineering Hydrology


The peaks over threshold (POT) series model has been used in hydrology to analyse extreme phenomena such as floods or precipitation amounts exceeding a certain threshold level. The results of a study treating two important aspects of the application of the POT model in hydrology are presented. This paper concentrates on the use of the POT model to study the seasonal variations in flood data in the Provinces of Quebec and New Brunswick (Canada). POT models are capable of taking seasonal variations in river-flow processes into account by considering exceedances from different seasons to be non-identically distributed. The study deals specifically with the choice of seasons to be entered into the model, emphasizing the importance of determining these seasons on the basis of the data on hand instead of taking the four usual seasons winter, spring, summer and fall, which might not be necessarily applicable to the specific region under study. A graphical procedure is proposed for the determination of seasons at some gaging sites in the Provinces of Quebec and New Brunswick. An appropriate partitioning of the year into seasons is obtained for different parts of these two Provinces. In addition, the transferability of information from a gaged basin to an ungaged basin is undertaken by applying multiple regression to the estimation of the threshold level from the physical characteristics of the basin.

Subject Headings: Seasonal variations | Floods | Hydrologic models | Hydrology | Regression analysis | Graphic methods | Basins | Mathematical models | Canada | Quebec | New Brunswick

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