Tidal flooding

Last updated
October 17, 2016 tidal flooding on a sunny day, during the "king tides" in Brickell, Miami that peaked at 4 ft MLLW. October 17 2016 sunny day tidal flooding at Brickell Bay Drive and 12 Street downtown Miami, 4.34 MLLW high tide am.jpg
October 17, 2016 tidal flooding on a sunny day, during the "king tides" in Brickell, Miami that peaked at 4 ft MLLW.

Tidal flooding, also known as sunny day flooding [1] or nuisance flooding, [2] is the temporary inundation of low-lying areas, especially streets, during exceptionally high tide events, such as at full and new moons. The highest tides of the year may be known as the king tide, with the month varying by location.

Contents

Tidal flooding is capable of majorly inhibiting natural gravity-based drainage systems in low-lying areas when it reaches levels that are below visible inundation of the surface, but which are high enough to incapacitate the lower drainage or sewer system. Thus, even normal rainfall or storm surge events can cause greatly amplified flooding effects. One passive solution to intrusion through drainage systems are one way back-flow valves in drainage ways. However, while this may prevent a majority of the tidal intrusion, it also inhibits drainage during exceptionally high tides that shut the valves. In Miami Beach, where resilience work is underway, the pump systems replace insufficient gravity-based systems. [3]

United States

Saltwater in drain on a bayfront street (Brickell Bay Drive) in Miami just up to street level; while not a direct flood, this inhibits normal passive, gravity-based drainage. Brickell Bay Drive drain at threshold of flooding during king tide 2016.jpg
Saltwater in drain on a bayfront street (Brickell Bay Drive) in Miami just up to street level; while not a direct flood, this inhibits normal passive, gravity-based drainage.
2016 Miami king tidal flood coupled with a three-inch rain causes up to two feet of flood water at a low spot on 23 Street in Edgewater. Miami tidal flooding with rain at high tide during king tides 38 Edgewater flooded car.jpg
2016 Miami king tidal flood coupled with a three-inch rain causes up to two feet of flood water at a low spot on 23 Street in Edgewater.

In Florida, controversy arose when state-level government mandated that the term "nuisance flooding" and other terms be used in place of terms such as sea level rise, climate change and global warming, prompting allegations of climate change denial, specifically against Governor Rick Scott. This amid Florida, specifically South Florida and the Miami metropolitan area being one of the most at risk areas in the world for the potential effects of sea level rise, and where the frequency and severity of tidal flooding events increased in the 21st century. [4] The issue is more bipartisan in South Florida, particularly in places like Miami Beach, where a several hundred million dollar project is underway to install more than 50 pumps and physically raise roads to combat the flooding, mainly along the west side of South Beach, formerly a mangrove wetland where the average elevation is less than one meter (3.3 feet).

In the Miami metropolitan area, where the vast majority of the land is below 10 ft (3.0 m), even a one-foot increase over the average high tide can cause widespread flooding. The 2015 and 2016 king tide event levels reached about 4 feet (1.2 m) MLLW, 3 feet (0.9 m) above mean sea level, or about 2 ft (0.61 m) NAVD88, and nearly the same above MHHW. [5] While the tide range is very small in Miami, averaging about 2 ft (0.61 m), with the greatest range being less than 2 m (6.6 ft), [6] the area is very acute to minute differences down to single inches due to the vast area at low elevation. NOAA tide gauge data for most stations shows current water level graphs relative to a fixed vertical datum, as well as mean sea level trends for some stations. During the king tides, the local Miami area tide gauge at Virginia Key shows levels running at times 1 foot (0.30 m) or more over datum.

Fort Lauderdale has installed over one hundred tidal valves since 2013 to combat flooding. Fort Lauderdale is nicknamed the "Venice of America" due to its roughly 165 miles (266 km) of canals. [7]

A recent University of Florida study correlated the increased tidal flooding in south Florida, at least from 2011–15 to episodic atmospheric conditions. [8] The rate was about 3/4 of an inch (19 mm) per year, versus the global rate of just over a tenth of an inch (3 mm) per year. [9]

History

The last remaining house on Holland Island that collapsed and was torn down in the 2010s as erosion and tides reached the foundation. Holland Island house.jpg
The last remaining house on Holland Island that collapsed and was torn down in the 2010s as erosion and tides reached the foundation.

Due to changing geography such as subsidence, and poorly planned development, tidal flooding may exist separate from modern nuisance flooding associated with sea level rise and anthropocentric climate change. The widely publicized Holland Island in Maryland for example has disappeared over the years mainly due to subsidence and coastal erosion. [10] In the New Orleans area on the Gulf Coast of Louisiana, land subsidence results in the Grand Isle tide gauge showing an extreme upward sea level trend. [11]

In March 2018, South Florida experienced significant coastal erosion and flooding outside of the usual king tide or hurricane season during a Nor'easter event. [12]

See also

Related Research Articles

Tide Rise and fall of the sea level under astronomical gravitational influences

Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun, and the rotation of the Earth.

Estuary A partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea

An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea.

Miami Beach, Florida City in Florida, United States

Miami Beach is a coastal resort city in Miami-Dade County, Florida, United States. It was incorporated on March 26, 1915. The municipality is located on natural and man-made barrier islands between the Atlantic Ocean and Biscayne Bay, the latter of which separates the Beach from the mainland city of Miami. The neighborhood of South Beach, comprising the southernmost 2.5 square miles (6.5 km2) of Miami Beach, along with downtown Miami and the Port of Miami, collectively form the commercial center of South Florida. Miami Beach's estimated population is 92,307 according to the most recent United States census estimates. Miami Beach is the 26th largest city in Florida based on official 2017 estimates from the US Census Bureau. It has been one of America's pre-eminent beach resorts since the early 20th century.

Salt marsh Coastal ecosystem between land and open saltwater that is regularly flooded

A salt marsh or saltmarsh, also known as a coastal salt marsh or a tidal marsh, is a coastal ecosystem in the upper coastal intertidal zone between land and open saltwater or brackish water that is regularly flooded by the tides. It is dominated by dense stands of salt-tolerant plants such as herbs, grasses, or low shrubs. These plants are terrestrial in origin and are essential to the stability of the salt marsh in trapping and binding sediments. Salt marshes play a large role in the aquatic food web and the delivery of nutrients to coastal waters. They also support terrestrial animals and provide coastal protection.

A rip tide, or riptide, is a strong, offshore current that is caused by the tide pulling water through an inlet along a barrier beach, at a lagoon or inland marina where tide water flows steadily out to sea during ebb tide. It is a strong tidal flow of water within estuaries and other enclosed tidal areas. The riptides become the strongest where the flow is constricted. When there is a falling or ebbing tide, the outflow water is strongly flowing through an inlet toward the sea, especially once stabilized by jetties. During these falling and ebbing tides, a riptide can carry a person far offshore. For example, the ebbing tide at Shinnecock Inlet in Southampton, New York, extends more than 300 metres (980 ft) offshore. Because of this, riptides are typically more powerful than rip currents.

A storm surge, storm flood, tidal surge or storm tide is a coastal flood or tsunami-like phenomenon of rising water commonly associated with low pressure weather systems. Its severity is affected by the shallowness and orientation of the water body relative to storm path, as well as the timing of tides. Most casualties during tropical cyclones occur as the result of storm surges. It is a measure of the rise of water beyond what would be expected by the normal movement related to tides.

Tidal creek The portion of a stream that is affected by ebb and flow of ocean tides

A tidal creek, tidal channel, or estuary is the portion of a stream that is affected by ebb and flow of ocean tides, in the case that the subject stream discharges to an ocean, sea or strait. Thus this portion of the stream has variable salinity and electrical conductivity over the tidal cycle, and flushes salts from inland soils. Tidal creeks are characterized by slow water velocity resulting in buildup of fine, organic sediment in wetlands. Creeks may often dry to a muddy channel with little or no flow at low tide, but with significant depth of water at high tide. Due to the temporal variability of water quality parameters within the tidally influenced zone, there are unique biota associated with tidal creeks which are often specialised to such zones. Nutrients and organic matter are delivered downstream to habitats normally lacking these, while the creeks also provide access to inland habitat for salt-water organisms.

Tidal range is the height difference between high tide and low tide. Tides are the rise and fall of sea levels caused by gravitational forces exerted by the Moon and Sun and the rotation of Earth. Tidal range is not constant but changes depending on the locations of the Moon and Sun.

A tidal river is a river whose flow and level are influenced by tides. A section of a larger river affected by the tides is a tidal reach, although it may sometimes be considered a tidal river if it has been given a separate name.

Climate change in Florida Climate change in the US state of Florida

The effects of Climate change in Florida is attributable to man-made increases in atmospheric carbon dioxide. Floridians are experiencing increased flooding due to sea level rise, and are concerned about the possibility of more frequent or more intense hurricanes.

Sea level rise The current long-term trend for sea levels to rise mainly in response to global warming

Since at least the start of the 20th century, the average global sea level has been rising. Between 1900 and 2016, the sea level rose by 16–21 cm (6.3–8.3 in). More precise data gathered from satellite radar measurements reveal an accelerating rise of 7.5 cm (3.0 in) from 1993 to 2017, which is a trend of roughly 30 cm (12 in) per century. This acceleration is due mostly to human-caused global warming, which is driving thermal expansion of seawater and the melting of land-based ice sheets and glaciers. Between 1993 and 2018, thermal expansion of the oceans contributed 42% to sea level rise; the melting of temperate glaciers, 21%; Greenland, 15%; and Antarctica, 8%. Climate scientists expect the rate to further accelerate during the 21st century.

Climate of Miami

Climate of Miami is classified as having a tropical monsoon climate. With hot and humid summers; short, warm winters; and a marked drier season in the winter. Its sea-level elevation, coastal location, position just above the Tropic of Cancer, and proximity to the Gulf Stream shape its climate. With January averaging 69.2 °F (20.7 °C), winter features warm temperatures; cool air usually settles after the passage of a cold front, which produces much of the little amount of rainfall. Lows sometimes fall to or below 50 °F (10 °C), with an average 3 such occurrences annually, but rarely 40 °F (4 °C); from 1981 to 2010, temperatures reached that level in only eight calendar years. Highs generally reach 70 °F (21 °C) or higher, and fail to do so on only an average of 12 days annually.

Climate change in Tuvalu

Global warming is dangerous in Tuvalu since the average height of the islands is less than 2 metres (6.6 ft) above sea level, with the highest point of Niulakita being about 4.6 metres (15 ft) above sea level. Tuvalu islands have increased in size between 1971 and 2014, during a period of global warming. Over 4 decades, there had been a net increase in land area in Tuvalu of 73.5 ha (2.9%), although the changes are not uniform, with 74% increasing and 27% decreasing in size. The sea level at the Funafuti tide gauge has risen at 3.9 mm per year, which is approximately twice the global average.

Coastal flooding occurs when normally dry, low-lying land is flooded by seawater. The extent of coastal flooding is a function of the elevation inland flood waters penetrate which is controlled by the topography of the coastal land exposed to flooding. The seawater can flood the land via from several different paths:

Coastal Risk Consulting

Coastal Risk Consulting, LLC. is an American startup climate adaptation technology and consulting company with headquarters in Plantation, Florida. Coastal Risk provides individuals, businesses, and local governments with climate impact modeling technology, available as an online software-as-a-service (SaaS), that allows property owners to assess their vulnerability to flooding related to sea level rise and climate change impacts and assists in adaptation and resiliency decision-making.

New York Harbor Storm-Surge Barrier

The New York Harbor Storm-Surge Barrier is a proposed barrier and floodgate system to protect the New York-New Jersey Harbor Estuary from storm surges. The proposed system would consist of one barrier located across the mouth of Lower New York Bay between Sandy Hook (N.J.) and Far Rockaway (N.Y.) and second on the upper East River to provide a ring of protection to most of the bi-state region. Through extensive use of floodgates, both barriers would have largely open cross-sections during normal conditions to minimize environmental impacts on the estuary and port operations.

Climate change in Delaware

Climate change in Delaware encompasses the effects of climate change, attributed to man-made increases in atmospheric carbon dioxide, in the U.S. state of Delaware.

Climate change in Maryland

Climate change in Maryland encompasses the effects of climate change, attributed to man-made increases in atmospheric carbon dioxide, in the U.S. state of Maryland.

Climate change in South Carolina

Climate change in South Carolina encompasses the effects of climate change, attributed to man-made increases in atmospheric carbon dioxide, in the U.S. state of South Carolina.

Climate change in Virginia

Climate change in Virginia encompasses the effects of climate change, attributed to man-made increases in atmospheric carbon dioxide, in the U.S. state of Virginia.

References

  1. Erik Bojnansky (March 9, 2017). "Sea levels are rising, so developers and governments need to band together: panel". The Real Deal . Retrieved March 10, 2017.
  2. "What is nuisance flooding?". National Oceanic and Atmospheric Administration . Retrieved December 13, 2016.
  3. Diana Madson (May 10, 2017). "Miami Beach spends millions to hold back the sea". Yale Climate Connections. Retrieved May 14, 2017.
  4. Wdowinski, Shimon; Bray, Ronald; Kirtman, Ben P.; Wu, Zhaohua (2016). "Increasing flooding hazard in coastal communities due to rising sea level: Case study of Miami Beach, Florida". Ocean & Coastal Management. 126: 1–8. doi:10.1016/j.ocecoaman.2016.03.002.
  5. "Water Levels - NOAA Tides & Currents (October 2016)". National Oceanic and Atmospheric Administration (NOAA). Retrieved November 1, 2016.
  6. "Virginia Key, FL - Station ID: 8723214". National Oceanic and Atmospheric Administration. Retrieved November 1, 2016.
  7. Amanda Ruggeri (April 4, 2017). "Miami's Fight Against Rising Seas". BBC News . Retrieved April 10, 2017.
  8. Justin Gillis (August 9, 2017). "The Sea Level Did, in Fact, Rise Faster in the Southeast U.S." The New York Times . Retrieved August 9, 2017.
  9. Pam Wright (August 10, 2017). "Sea Levels Have Risen Faster in Southeast U.S., and Scientists Think They Know Why". The Weather Channel . Retrieved August 10, 2017.
  10. Wheeler, Timothy B. (October 22, 2010). "Holland Island house collapse 'end of an era'". The Baltimore Sun . Retrieved November 2, 2016.
  11. "Mean Sea Level Trend 8761724 Grand Isle, Louisiana". NOAA. Retrieved November 24, 2016.
  12. David Sutta (March 5, 2018). "Massive Waves Push Sand, Water Inland And Cause Flooding Issues In Dania Beach". WFOR-TV . Retrieved March 8, 2018.