Sea Water Levels at Sewells Point, VA
With the end of the year, it is a good time to recap the data we have on flooding events and sea level rise for the Hampton Roads region.
Hourly Data at Sewells Point
Average Annual Sea Level at Sewells Point
Because this is hourly data it is highly variable. Here is the annual average of the hourly data from Sewells Pt.
10 year moving average at Sewells Point
We can take a 10 year moving average of the annual average to smooth out the interannual variations to get a better view of the long term trend.
Hours per year of 'Nuisance Flooding'
The lower panel shows the hourly Sewells Point water level. The solid horizontal line shows 0.53 m - the nuisance flood level. Sea level is rising causing there to be more nuisance flooding hours.
Return Period of Flooding Events
Red line - 2050 with 0.5 m (1.5 feet) sea level rise - If sea level rises 0.5 meters as expected by 2050 a one-meter flooding event will be every year or more often and a 1.4 meter flood every 2 to 3 years.
The way to interpret this that flooding events that occurred once during a Hampton Roads resident's lifetime will occur several times during their children's.
Rate of Sea Level Rise
The mean sea level trend is 4.59 millimeters/year with a 95% confidence
interval of +/- 0.23 mm/yr based on monthly mean sea level data from
1927 to 2015 which is equivalent to a change of 1.51 feet in 100 years."
The Past Year - 2016Here are the Sewells Pt plots for the past year
I've labeled the major storm events. Note I'd like to know what the early May event was called.
2016 compared to other years
You will notice that the highest water levels during any year are often in September. This is because the ocean waters are warmest then and they have expanded - making sea level higher. This is a seasonal effect.
Florida Current Transport
The reduced transport in early October coincided with Hurricane Mathew when is slowed over the Florida Current and apparently the southward winds slowed the Current. More on this from a paper Tal Ezer submitted.