Hurricane Impact Report* for Galveston City Hall, Galveston, Texas

* Sample only (actual values will differ)

 

Location Characteristics:

Galveston, Texas lies across the entrance to Galveston Bay, an inlet of the Gulf of Mexico. Long causeways connect the city with the mainland, Houston, and Texas City. Galveston remains a port of entry and is also a destination for cruise ships. Oil refining and shipbuilding are major industries, and the city has metal fabricating, printing, seafood processing, and the manufacture of steel containers. It is also a beach and fishing resort, with its attractions enhanced by pink and white oleanders, bougainvillea, and other subtropical blooms. Its climate and location make Galveston a prime target for tropical activity. Due to its terrain and island location, it is less likely to experience heavy rainfall induced flooding than the mainland (Houston). City Hall is located in the middle of the Island and is surrounded by two story homes and low rise buildings.

 

 

 

Wind Impact

The following report indicates the estimated maximum wind speeds experienced at this specific location from 1851-2002 due to tropical cyclones.

(Sample only)

Category of Wind (Safir Simpson Scale)

Damage *

Occurrences by Wind Category

Chance of occurrence of category wind or greater, per year

Period occurrence

(every x years)

0: 30-63 knots

Minor

55

47%

Every 2.1 years

1: 64-82 knots

Minimal

12

11%

9 years

2: 83-95 knots

Moderate

1

3.3%

30 years

3: 96-113 knots

Extensive

2

2.6%

39 years

4: 114-134 knots

Extreme

2

1.3%

77 years

5: 135+ knots

Catastrophic

0

-

-

 

 

 

 

 

 

The highest wind speeds experienced since 1851 was 119 knots (137 mph) with gust to 137 knots (157 mph).

 

These statistics indicate a location that is prone to experience an above average number of storms. Although the vast majority of the winds experienced by these storms are category 1 or less, there have been 4 that have caused extensive to extreme damage.

 

See detailed description of Category Wind Damage at the end of this report. 


Storm Surge Potential

 

Being situated along the Gulf Coast, with a shallow coastal reef, this area is prone to significant storm surge potential.

 

Storm Surge Inundation Report:
The report below indicates the maximum storm surge flooding at this specific location for each category of storm.
 

(Sample only)

Location

Elev.

(ft)

Cat 1

Inund.

AGL (ft)

Cat 2

Inund.

AGL (ft)

Cat 3

Inund.

AGL(ft)

Cat 4

Inund.

AGL(ft)

Cat 5

Inund.

AGL(ft)

Galveston City Hall, Galveston, TX

6

2.0

3.5

7.4

11.0

13.7

 

 

Storm Surge Inundation Maps:
The maps indicate the maximum areas of storm surge flooding for each location on the map. I.E. since some areas of the map may experience the highest flooding with wind from a certain direction and other areas experience the highest flooding with winds from a difference direction, you would never see a pattern of flooding as represented by the image.

 

(Samples only)

 

Category 1

 

Category 2

 

 

Category 3

 

 

Category 4

 

 

Category 5


* Detailed description of Category 1 -5 wind damage.

Category One Hurricane:

Winds 74-95 mph (64-82 kt or 119-153 km/hr). Storm surge generally 4-5 ft above normal. No real damage to building structures. Damage primarily to unanchored mobile homes, shrubbery, and trees. Some damage to poorly constructed signs. Also, some coastal road flooding and minor pier damage

Category Two Hurricane:

Winds 96-110 mph (83-95 kt or 154-177 km/hr). Storm surge generally 6-8 feet above normal. Some roofing material, door, and window damage of buildings. Considerable damage to shrubbery and trees with some trees blown down. Considerable damage to mobile homes, poorly constructed signs, and piers. Coastal and low-lying escape routes flood 2-4 hours before arrival of the hurricane center. Small craft in unprotected anchorages break moorings

Category Three Hurricane:

Winds 111-130 mph (96-113 kt or 178-209 km/hr). Storm surge generally 9-12 ft above normal. Some structural damage to small residences and utility buildings with a minor amount of curtain wall failures. Damage to shrubbery and trees with foliage blown off trees and large trees blown down. Mobile homes and poorly constructed signs are destroyed. Low-lying escape routes are cut by rising water 3-5 hours before arrival of the center of the hurricane. Flooding near the coast destroys smaller structures with larger structures damaged by battering from floating debris. Terrain continuously lower than 5 ft above mean sea level may be flooded inland 8 miles (13 km) or more. Evacuation of low-lying residences with several blocks of the shoreline may be required

Category Four Hurricane:

Winds 131-155 mph (114-135 kt or 210-249 km/hr). Storm surge generally 13-18 ft above normal. More extensive curtain wall failures with some complete roof structure failures on small residences. Shrubs, trees, and all signs are blown down. Complete destruction of mobile homes. Extensive damage to doors and windows. Low-lying escape routes may be cut by rising water 3-5 hours before arrival of the center of the hurricane. Major damage to lower floors of structures near the shore. Terrain lower than 10 ft above sea level may be flooded requiring massive evacuation of residential areas as far inland as 6 miles (10 km).

Category Five Hurricane:

Winds greater than 155 mph (135 kt or 249 km/hr). Storm surge generally greater than 18 ft above normal. Complete roof failure on many residences and industrial buildings. Some complete building failures with small utility buildings blown over or away. All shrubs, trees, and signs blown down. Complete destruction of mobile homes. Severe and extensive window and door damage. Low-lying escape routes are cut by rising water 3-5 hours before arrival of the center of the hurricane. Major damage to lower floors of all structures located less than 15 ft above sea level and within 500 yards of the shoreline. Massive evacuation of residential areas on low ground within 5-10 miles (8-16 km) of the shoreline may be required
 

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