SEASONAL VARIATION IN EXTREME WAVE HEIGHT ESTIMATION FOR NIGERIAN OFFSHORE OILFIELDS USING GUMBEL DISTRIBUTION
Keywords:
Extreme Wave Height, Return Period, Gumbel Distribution, Peak Period, Estimated, Forcados, Asabo, Bonny, Bonga, Offshore, Generalized Extreme Value, Peak-Over-Threshold, Hindcast, seasonal variationAbstract
Accurately estimating extreme wave heights for various return periods is critical in the design of
offshore structures. This study employs Gumbel distribution to analyze historical wave data and
predict extreme wave heights for 10-year, 50-year, and 100-year return periods in the West African
offshore region, focusing on four key oilfields: Asabo, Bonga, Bonny, and Forcados. Findings
reveal significant variations between seasonal and annual extreme wave heights, with the highest
values consistently occurring during the rainy season. The percentage variation in extreme wave
heights computation between annual and rainy season data sets was found in Bonny and Forcados
to the tune of about 14% for 10-year extreme wave height, 10% in Bonny for 50-year and 100
year EWH. It became evidenced that EWH computed based on annual data is underpredicted
compared to extreme wave heights of rainy seasons. It is also found that these variations appear
to be increasing as the water depth is decreasing, this study stresses a path ahead for sustainable
and robust extreme wave determination for offshore structural design activities considering large
weather variations in the two seasons in West Africa. Moreso, understanding the seasonal and
annual variations of these extreme waves is crucial for improving offshore engineering design and
risk assessment in this region.
