Southern Lake Borgne
About Southern Lake Borgne |
Storm Surge History |
We have defined the Southern Lake Borgne area as the small fishing communities of Bayou Dupre, Shell Beach and Yscloskey, Louisiana. These communities are located in the wetlands east of metro New Orleans. The fishing industry in these communities is diverse, with fishermen working in the oyster, shrimp and crab industries. Onshore businesses support these industries through seafood processing and distribution. Lake Borgne is also the site of the Battle of Lake Borgne, which involved British and American ships during the War of 1812.
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U-Surge provides high water marks from 59 hurricanes and tropical storms at Pensacola since 1890. Hurricane Frederic (1979) generated the highest storm tide on record, as the water level reached 12 ft above the Annually-Adjusted MSL (AAMSL). Hurricane Ivan's (2004) 11.41-ft storm tide reached second place; this destructive flood event remains fresh in the local memory. Two major floods in the early 1900s impacted Pensacola- an unnamed hurricane in 1906 generated a storm tide 10 ft and the Great Miami Hurricane of 1926 redeveloped in the Gulf and pushed a 9.41-ft storm tide at Pensacola. These four hurricanes generated water levels substantially higher than other events on record and they all occurred in September.
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Infographics
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Histogram
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Time Series
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Most Severe Surges
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This histogram provides the maximum water levels of the 32 recorded storm tide events along Southern Lake Borgne since 1900. The events are ordered from the highest water level (Rank = 1) to lowest (Rank = 32). These events are not placed in chronological order. All data are detrended to remove the influence of relative sea level rise, so they represent water levels above an Annually-Adjusted Mean Sea Level (AAMSL).
This time series provides maximum water levels from 59 recorded storm tide events at Pensacola since 1890. These events are ordered chronologically from oldest (left) to newest (right). The numerous low-magnitude events in recent decades are influenced by both climate and data availability. All data are converted to NAVD88 datum, however, the data are intentionally not detrended, so the influence of relative sea level rise is included. SLR trend taken from NOAA tide gauge at Pensacola.
Statistics/ Return Period
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Return Period Graph
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Extreme Water Levels
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Storm tide return levels graph for Southern Lake Borgne. This graph uses a log-linear regression plot based on observed data from 1900-2018 (119 years). The graph uses the Weiboll Plotting Position Formula, whereby the probability of an extreme event occurring is Rank/ (n+1), where "n" is the number of years in the data record. These data have been detrended to remove the influence of sea level rise and all data are plotted relative to Annually Adjusted Mean Sea Level (AAMSL). The regression line represents the line of best fit and indicates return levels (y-axis) for various return periods (x-axis).
Return Period |
Storm Tide Level (Feet above AAMSL) |
500-year |
Value |
200-year |
19.28 |
100-year |
16.53 |
50-year |
13.78 |
25-year |
Value |
10-year |
Value |
Extreme water levels above Annually-Adjusted Mean Sea Level (AAMSL) with long-term sea level rise removed. The correct way to interpret these levels is as follows: Based on a log-linear regression of observed data from 1890-2018, storm tide levels at Pensacola should equal or exceed 9.37 ft every 100 years, on average, above the annually-adjusted MSL. According to the regression equation, the Hurricane Katrina's 18.7-foot storm tide was a 173-year event.
Sea Level Rise and Future Extreme Water Levels
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Past SLR Graph
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Future SLR Graph
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Future SLR Table
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Future Extreme Water Levels
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Future Extreme Water Levels Graph
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Year |
100-Year Flood Intermediate SLR |
100-Year Flood Intermediate-High SLR |
2000 |
9.73 |
9.73 |
2020 |
10.19 |
10.32 |
2040 |
10.71 |
11.04 |
2060 |
11.44 |
12.19 |
2080 |
12.32 |
13.63 |
2100 |
13.37 |
15.57 |
This table provides future 100-year water levels above NAVD88 datum. These numbers are calculated by adding four values: 1) The 100-year storm tide listed in the Statistics/ Return Period section- measured in feet above AAMSL; 2) An adjustment from MSL to NAVD88, which involved adding 0.30 ft to all water levels for Pensacola; 3) A conversion from water levels in 1992 (the mean year of the Present Epoch for Pensacola tide gauge data) to 2000, based on a long-term SLR rate of 0.76 ft/ century, which meant adding 0.06 ft; 4) Sea-Level rise projections from NOAA (2017), shown in the Future SLR Graph and Table above.
Extreme water level predictions for the 100-year coastal flood event at Pensacola. All of these projected values pertain to water levels for the "100-year storm" (1% annual chance) in the future. This analysis assumes stationarity in the flood level above the Annually Adjusted Mean Sea Level (AAMSL), so the increase in values are completely due to sea-level rise. According to this graph, there is a 1% chance that water levels will equal or exceed 12.19 feet in the year 2060, according to the intermediate-high SLR projection. These values do not account for wave action in velocity zones.
Data Sources
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NOAA Tide Gauge
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Data-Selection Circle
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Tide Gauge Site: Pensacola, FL 8729840
Operation: National Ocean Service (NOS) Coordinates: Lat: 30.4033 Lon: -87.2117 6-Min Water Level Data November 19, 1996 - September 16, 2004 January 5, 2005 - Present Hourly Water Level Data May 1, 1923 - August 31, 1950 March 9, 1951 - September 16, 2004 January 5, 2005 - Present The NOS tide gauge at Pensacola provides verified hourly data since 1923 and verified 6-min data since 1996. |
Pensacola's 59 high water marks come from a small geographic area near the city's waterfront. This tightly-clustered area provides a highly homogenous dataset that come from the same sample population. The data come from within a 2-mile data-selection circle centered on the coordinates: Lat: 30.4078 N, Lon: -87.2153 W.
Missing Data
We have identified five hurricanes/ tropical storms since 1900 that may have generated storm tides exceeding 4 ft (1.22 m) near Pensacola, but a literature review does not yet provide data. These maps are provided by Unisys Corporation
Storm Surge Multimedia
Note: All of these pics/ video were taken from Pensacola area
Hurricane Nate (2017)
Nice storm surge video at Pensacola. At 51 seconds into the video do you see evidence of a nice rip current pushing offshore? Look for elongated area of white water perpendicular to the coast. Any coastal experts want to confirm this?
Hurricane Isaac (2012)
Hurricane Katrina (2005)
Hurricane Ivan (2004)
Link: https://www.youtube.com/watch?v=o_uzqfhwc4k&t=196s. Excellent storm surge footage at several places in this video. The footage at 2:45 is amazing...shot from a parking garage in the dark. This video was the first to teach me what storm surge really looks like...I remember that I was surprised to see the waves were so low-magnitude/ high-frequency. Excellent work, Mike!
Frederic (1979)
Librarians at Pensacola Library sent this image
Unnamed (1932)
Great Miami Hurricane (1926)
Link: http://www.hurricanecity.com/images/4-1926%20hurricane.jpg
Unnamed (1906)
Pensacola Harbor in 1906. Link: https://www.floridamemory.com/items/show/38376