The problem of determining the threshold for statistical analysis by the POT method: Application to wave data on the Moroccan Atlantic coast

Hosny Bakali,Najat Serhir,Ismail Aouiche

doi:10.1051/e3sconf/202131404002

Hosny Bakali, Najat Serhir + Show 1 more

Open Access

https://doi.org/10.1051/e3sconf/202131404002

Copy DOI

Abstract

In a study of extreme waves by the Peak Over Threshold (POT) method, the determination of the threshold of data censoring is an essential step. A wrong choice of the threshold can lead to erroneous results of the wave height design and consequently a bad design of maritime structures such as breakwaters for deep sea ports. In this study, we analyzed the influence of the threshold variation on the results of the hundred-year return period waves, generally considered for the design of maritime structures. The sensitivity study allowed us to confirm that the exponential model is the best probability distribution to describe wave data in two points on the Moroccan Atlantic coast for the wave data period from 1958 to 2019. This study also confirmed that a wrong choice of the statistical distribution and a wrong choice of the threshold lead to significant errors in the estimation of design wave height.

Highlights

The determination of the design wave height is a crucial step in the design of maritime structures
4 Conclusion & Discussion Statistical study of wave data over a 62-years data period assumes that the data is stationary and there is no long-term variation due to climate change
This hypothesis is not valid according to studies of wave climate evolution during the 20th century [16]

Summary

Introduction

The determination of the design wave height is a crucial step in the design of maritime structures. The significant wave height generally considered is the 100 years return period wave, which is determined by statistical analysis of the wave data available over periods of a few decades. The extreme waves heights are determined by extrapolation from statistical distributions fitted to the wave data. To select the data for statistical analysis, two methods are used:. The first approach is called BLOCK MAXIMA method [2]. The data is the maximum values over regular time intervals, generally taken equal to one year. In this particular case, the method is referred to by the “ANNUAL MAXIMA METHOD (MA)”

Methods

Results

Conclusion