Note: If you’re a Climate Change Denier don’t bother to read this. I’m not interested in a debate.
The threat of sea level rise and increased storm surge is a natioinal challenge. (see interactive map and tidal flooding predication by city) s Already this has been addressed in New Orleans, London, Rotterdam in The Netherlands and Venice Italy and plans are being evaluated for East Coast cities here such as Boston, New York City and Miami Beach and the urban infrastructure in Rotterdam,. This interactive map created by Climate Central snows the projected flooding for US coastal cities depending on the climate’s overall temperature rise. Enter a city in the upper left hand corner.
In 1928 fourteen people were said to have died after the Thames flooding with a further 307 dying during the North Sea flood of 1953. These deaths led to the barrier being built in the late 1970s before being opened officially in 1984
From Daily Mail February14,2014
The Thames Barrier has two types of gates: Falling Radial Gates that sit above the river and Rising Sector Gates which rest on the river bed. Individual gates can be closed in ten minutes but the whole barrier takes around an hour and a half to close completely. If a picture is worth a thousands words then a video must be priceliess.
When fully raised, the barrier creates a solid steel wall that stops water flowing upstream towards the capital. The Thames Barrier is only be reopened once the water level upstream of the barrier matches the level downstream. Once a decision has been made to reopen it, a controlled amount of water is passed under the gate and up the Thames. The English capital is vulnerable to flooding and high tides from surges traveling down from the North Sea towards the English Channel and Thames Estuary.
The stormiest and wettest period of weather for a century has seen the barrier, which protects closed a record 29 times since December – compared to 35 times between 1990 and the end of 1999. The construction cost was around £534 million ($2.08 billion at 2016 prices) with an additional $160 million for river defenses.
New Orleans suffered enormously from Hurricane Katrina. According to the Five Thirty Eight website as of 2015 they still don’t’ have what they feel is an accurate number because of physical and institutional problems after the event. A possible A possible number is over 1,200. FEMA lists the number as over 1,800 including deaths in Alabama, Mississippi, Georgia and Florida as well as Louisiana.
According to FEMA the costs totaled over $108 Billion. While wind damage was part of the problem the levee collapse and resulting flooding was the major problem.
After Katrina, the US Army Corps of Engineers built a 1.8-mile barrier along Lake Borgne, a lagoon of the Gulf of Mexico to encircle New Orleans. They spent nearly $14.5 Billion (NPR) on fortifications to protect some 900,000 people living in the toe-tip of Louisiana.
The ring of protection around New Orleans is a major improvement over the old system of levees and flood walls that failed catastrophically. Completed in 2013 the Corps strengthened 350 miles of hurricane barriers and built massive new flood gates using better construction materials and more advanced computer storm modeling. They’ve also updated pumping stations to de-water the city.
The specific purpose (from Wikipedia) of the Inner Harbor Navigation Canal (IHNC) surge barrier is to reduce the risk of storm damage to some of the region’s most vulnerable areas – New Orleans East, metro New Orleans, the 9th Ward, and St. Bernard Parish. This project is designed to protect these areas from storm surge coming from the Gulf of Mexicoand Lake Borgne.
There is a debate on the cost of ongoing maintenance. Without this the system will deteriorate over time. The city says the Corp should pay a major part and the Corp doesn’t agree. If not settled the expense will have been for naught.
While I’m writing this the city experienced flooding from recent intense rainfall. in a different area than the hard hit sites from Katrina. Apparently 16 of the 80-odd pumps were out of service some ffor maintenance. June through November is Hurricane Season in the Atlantic. Do you think they could schedule routine maintenance another time? Jeesh!
For decades Venice Italy was known to be sinking from pumping of groundwater and the centuries’ long weight of heavy stone buildings on the particular type of subsoil. Furthermore, another contributor is believed the meeting o two tectonic plates deep in the earth. The city just can’t get a break. After all it is basically 117 islands surrounded by the ocean.
Then they thought the subsidence stopped. Then a 2012 paper from the Scripps Institution of Oceanography in San Diego said that the city is still sinking at the rate of 0.07-0.12 inches per year, but the sea is rising at the same amount so in 20 years is will have risen about 3.2 inches. Currently areas of the city are subject to ‘acqua alta’, which is a convergence of high tides and a strong sirocco wind, often reaches a height of 3 ½ feet. In 2016 parts od the city was under than five feet of water. The side walls of the canals are brick and their periodic submergence under water accelerates their mortar deterioration as well as the walls of historic buildings.
In order to mitigate this the MOSE (MOdulo Sperimentale lettromeccanico, Experimental Electromechanical Module) project was developed to protects the city of Venice, Italy and the Venetian Lagoon from tidal flooding. The project is an integrated system consisting of rows of mobile gates installed at the Lido, Malamocco, and Chioggia inlets that are able to isolate the Venetian Lagoon temporarily from the Adriatic Sea during high tides.
Together with other measures, such as coastal reinforcement, the raising of quaysides, and the paving and improvement of the lagoon, MOSE is designed to protect Venice and the lagoon from tides of up to 9.8 ft. The cost was $6.36 Billion. The future problem is the continued subsidence will probably leave the devices too short to be effective.
Video of how it works
Video of inaugural operation
The area that eventually became The Netherlands, has forty percent of its land below mean sea level and sixty percent at risk from flooding(Wikipedia) 3.3 ft above sea level
current map notice location of Amsterdam flooding no dikes
The’ recorded history of flooding in Wikipedia begins in 838 when over 800 people died from flooding in the Northwest of the county, There followed a pattern of two or three floods per century most without a fatality count until the Great Storm of 1703 which reached from Wales to central and southern Britain, the Low Land countries and northern Germany. Thousands were killed by flooding. During the next two centuries there were five significant floods.
Modern day control projects started with the Zuiderzee Works in the 1930’s This is a system of dams, land reclamation, and water drainage works. The goal of the project was the damming off of the Zuiderzee, a large shallow inlet of the North Sea. The dam was built in 1932–33, separating it from the North Sea.
The Delta Plan
The Delta Plan with a more all-encompassing scope was put off because of World War II. In 1937 another study said the defenses in the southwest section where three major rivers came together could not withstand a major storm surge. The report proposed to dam all the river mouths but because of the scale of the project and World War II all discussion was shelved. Work was restarted in 1950.
The 1953 Great Flood covered The Netherlands, England, Belgium and Scotland. The Netherlands sustained 1,830 deaths, nine percent of total Dutch farmland flooded, 30,000 animals drowned, 47,300 buildings were damaged of which 10,000 were destroyed. (Wikipedia). This gave impetus to speed up work and a number of dams were built. There were two large projects planned. The reportedly more expensive one was the Oosterscheldekering, a storm surge barrier which is only closed during storms. It is the most well-known
In 1976, under pressures from environmental groups and the fishing industry, it was decided not to close off the Oosterschelde estuary by a solid dam but instead to build the Oosterscheldekering, a storm surge barrier which is only closed during storms. It is the most well-known (and most expensive) dam of the project.
TThe second project was to protect the city of Rotterdam. A storm surge would threaten about 1.5 million people/. However, closing off the river mouth would be very detrimental for the Dutch economy, as the Port of Rotterdam, one of the biggest sea ports in the world, uses it. Eventually, the Maeslantkering was built in 1997. It is a set of two swinging doors (note, the video is 8 minutes) that can shut off the river mouth when necessary, but which are usually open. It is forecast to close about once per decade. Up until January 2012, it has closed only once, in 2007. The annual test of the closing is a community event. Holland is a very civic minded country.
With this construction finished the Delta Project was completed. The system cost tens of billions of euros over more than four decades and includes thousands of miles of dikes and canals that can carry away excess water and levees along the coasts.
Wikipedia writes that the sea defenses are continuously being strengthened and raised to meet the safety norm of a flood chance of once every 10,000 years for the west, which is the economic heart and most densely populated part of the Netherlands, and once every 4,000 years for less densely populated areas. The primary flood defenses are tested against this norm every five years. In 2010 about 800 km of dikes out of a total of 3,500 km failed to meet the norm.
Rotterdam, being right on the North Sea has a heightened sensitivity to rising sea levels and storm surges. Besides the major projects to protect them the City is changing its landscape to address the future. Those efforts will part of a future blog