Tag Archives: Sea Level Rise

Barrier islands and sea-level rise

Orrin Pilkey Barrier Islands

By Orrin H. Pilkey, Professor Emeritus of Earth Science at Duke University’s Nicholas School of the Environment.

It had to happen. As more and more buildings are built along the North Carolina shoreline and as shoreline-retreat catches up with these buildings (many of which are rentals), the pressure to bend the coastal regulations to save buildings becomes almost unbearable. But maintaining the shoreline status quo and protecting all buildings eventually means loss of our developed beaches. It also means we will be ill- prepared for sea-level rise.

Currently in North Carolina sea level is rising about 1.5 feet per century over a land slope that averages 1: 2000. This means a 1-foot rise could cause a shoreline retreat of more than a third of a mile (in theory). Already some of the erosion on our shoreline is due to sea-level rise, which explains why a spring high tide flooded N.C. 12 last year near Rodanthe.

Over the next 100 years, according to recent estimates by Professor Hal Wanless of the University of Miami, we should expect 5 to 6 feet of sea-level rise. This is close to the North Carolina sea-level rise panel’s maximum estimate of 4.6 feet over the same time frame. The Wanless projection is a bit more up-to-date because it considers a whole series of warming events related to disappearing sea ice in the Arctic Ocean that may contribute 1 foot of rise.

Projections of the rise by scientists and government agencies are always on a century basis, but our problems will arise much quicker than that. To put this into a practical context, a 2- to 3-foot rise, which may be reached as soon as 40 to 60 years from now, means the end of barrier island development.

Why? Erosion rates will be even faster than at present, and “nourished” beaches will no longer stay put. Our barrier islands will have to be surrounded in their entirety by seawalls to protect them from storm waves and inundation. At the same time funding for local beach communities is in doubt, because protecting major coastal cities and infrastructure will be a higher government priority.

Here in North Carolina, efforts to preserve our beaches climaxed when the Coastal Resources Commission ordered sandbags removed a couple of years ago. Sandbags are no different than concrete walls in terms of the erosion they cause to a beach (take a walk or drive along Seagull Drive on South Nags Head for an example). Shortly after the sandbag removal order was issued, however, a moratorium on it was declared, and was renewed this year.

At the same time the beachfront communities, especially exclusive Figure Eight island, began pushing for terminal groins (jetties) against the advice of the state’s marine geology and oceanography community.

Terminal groins and sandbags aren’t the only problems. The proposed new Oregon Inlet bridge assures that the state will face long and costly decades of holding an island in place solely to protect a single road. High-rises continue to be built on various barrier islands, effectively preventing any sort of flexible response to the rising sea.

Now is not the time to drop the ball. Global change is already upon us.

North Carolina needs to preserve the regulations that have served us well for decades. This includes removal of sandbags as regulations require. We need to go further and prohibit all high-rises on any barrier island. And when the time comes, we must accept that buildings that can no longer be protected through reasonable means must be demolished or moved back.

If we don’t do these things we eventually will be Florida-ized. That state has hundreds of miles of shorefront lined with high-rises protected by beach-destroying seawalls. This type of shortsighted barrier island development has a dismal future 40 years from now.

North Carolina’s coastal management program needs more backbone now than ever before. Gov. Beverly Perdue is about to appoint new members of the CRC. If the new appointees maintain the status quo and continue to protect all beachfront development, the state’s beaches will continue their downward plunge. Perdue should take the long view.

Original Article


Op Ed, The Rising Sea, Orrin Pilkey and Rob Young

By Orrin H. Pilkey, Professor Emeritus of Earth Science at Duke University’s Nicholas School of the Environment.

Tuesday, August 25, 2009

What little serious attention that has been paid to the rising sea level in North Carolina has mainly focused on the beaches and barrier islands and the threat to beachfront Mcmansions. But sea level rise is a major threat to the lands behind the barrier islands, to the towns and villages scattered about and especially to the states agricultural industry.

In our new book, The Rising Sea, we suggest that coastal areas can expect a minimum of 3 feet of sea level rise by the year 2100. This is made all the more significant because the average slope of the land in the lower coastal plain of North Carolina is 1 to 2000 meaning that a sea level rise of 1 foot will move the shoreline back 2000 feet. The slope of the mainland behind Pamlico and Albermarle Sounds however is typically 1 to 10,000 and even less, meaning that a 1 foot rise will flood more than 2 miles inland.

A number of small towns along the sounds and estuaries will be impacted. If you can see a marsh from your town you may be in trouble. Some like Plymouth, Washington and Columbia are entirely at low elevations and could be completely inundated by a 3 foot rise. Dozens of other small towns and even Wilmington will soon find their storm drainage systems and sewage plants in need of replacement.

But mainland flooding is only part of the problem. Storm surges from future Hurricanes and northeasters as well as spring tides will intrude ever further into the mainland as seas rise. Salt water intrusion will occur both into the groundwater and up the rivers and streams and render much agricultural land completely useless. River floods will increase in magnitude as the rising sea level provides a higher base level at the river mouth. As sea level inches up, the efficiency of drainage from many farmers fields will decrease and water logging will be prolonged. As the ground water table moves up the roots of certain tree species will be flooded and large scale killing of forests will occur even before salinization. Already too many trees are dying from this cause along estuarine shorelines in NC.

Shoreline erosion along estuarine shorelines will increase and since restrictions on shoreline stabilization on such shorelines are effectively non-existant in NC. Sea walls will sprout leading eventually to widespread loss of salt marshes.

All of these things are already happening on a small scale in our lower coastal plain. Salt water is extending ever further up rivers, salt water is intruding ion some areas and fields are draining more poorly than a decade ago.

There aren’t many things that can be done to mitigate the serious damage that will be caused to agriculture in North Carolina’s lower coastal plain. Perhaps the most likely to succeed at least temporarily would be changing to crops that are more resistant to a higher water table. A more costly and also temporary approach would be to increase the efficiency of field drainage by excavating new ditches and even installing pumps. Levee construction is already being carried out for a number of small towns (such as Swan Quarter) but this most likely wont work for agricultural areas. Installing gates at river or inlet mouths in Dutch-like fashion is clearly out of the question because of the huge costs involved. Its important to remember when North Carolina farmers are in trouble so will also be the farmers all along the East Coast and Gulf coast coastal plain from New Jersey to Texas. Considering that the cities such as New York, Boston and Philadelphisa will be in trouble it is likely that government help to solve the problem will not be impressively large.

North Carolina has instituted a new sea level rise panel to examine the impact of sea level rise. We hope the fate of thousands of beach cottages wont overshadow the future of North Carolina lower coastal plain farmers. They are important too.

In Low-Lying Bangladesh, The Sea Takes a Human Toll

flood-bangladesh
Too wet to live on. One of the flood victims in Bangladesh shows the ground of his hut that is yet unlivable.Captions and Photo source: ©© Amio James Ascension

Excerpts;

Jonathan Bjerg Møller, 2 videos: “Aila’s Victims” and “Wahidul’s Story.”

Danish photographer and filmmaker Jonathan Bjerg Møller recently spent nine months in Bangladesh, chronicling the lives of people struggling to survive just a few feet above sea level…

Read Full Article And Watch Video, Yale E360

Sea Level to Rise Even With Aggressive Geo-Engineering

waves-storm-coastal-care
Photograph: © SAF — Coastal Care

Excerpts;

New findings by international research group of scientists from England, China and Denmark just published suggest that sea level will likely be 30-70 centimetres higher by 2100 than at the start of the century even if all but the most aggressive geo-engineering schemes are undertaken to mitigate the effects of global warming and greenhouse gas emissions are stringently controlled…

Read Full Article, Science Daily

Proceedings of the National Academy of Sciences
Excerpt published August 23 in the journal PNAS Proceedings of the National Academy of Sciences, Efficacy of geoengineering to limit 21st century sea-level rise..

Kingscliff Battles Beach Erosion, Australia

coastal-erosion
Coastal erosion. Photograph: © SAF — Coastal Care

Excerpts

Two months ago, photographer Tania Phillips stood where the Cudgen Creek meets the Pacific Ocean at Kingscliff on the far north coast and noticed that the beach was washing away.

Kingscliff residents fear their idyllic seaside village may never be restored to its former glory after the besieged coastline copped a further battering this week…

Read Full Article, Gold Coast News

Watch a Slideshow, Science Daily

Erosion doubles along Alaska’s Arctic coast:: Cultural and Historical Sites Lost

alaska-erosion-usgs
A cabin along the Arctic Alaska coastline was recently washed into the ocean because the bluff it was sitting on top of was eroded away. Captions and Photo source: ©© Benjamin Jones, USGS

Excerpt, from USGS.

Coastal erosion has more than doubled in Alaska, up to 45 feet per year, in a 5-year period between 2002 and 2007 along a 40-mile stretch of the Beaufort Sea. A U.S. Geological Survey-led study reveals that average annual erosion rates along this part of the Beaufort Sea climbed from historical levels of about 20 feet per year between the mid-1950s and late-1970s, to 28 feet per year between the late-1970s and early 2000s, to a rate of 45 feet per year between 2002 and 2007. The study was published in the February,18th 2009 issue of Geophysical Research Letters, a publication of the American Geophysical Union.

USGS scientist and lead author Benjamin Jones cautioned that it is possible that the recent patterns documented in their study may represent a short-term episode of enhanced erosion. However, they may well represent the future pattern of coastline erosion in the Arctic. “Erosion of coastlines is a natural process, and this segment of coastline has historically eroded at some of the highest rates in the circum-Arctic, so the changes occurring on this open-ocean coast might not be occurring in other Arctic coastal settings,” said Jones.

The authors proposed that these recent shifts in the rate and pattern of land loss along this coastline segment are potentially a result of changing arctic conditions, including declining sea ice extent, increasing summertime sea-surface temperature, rising sea level, and increases in storm power and corresponding wave action.

“Taken together, these factors may be leading to a new era in ocean-land interactions that seem to be repositioning and reshaping the Arctic coastline,” wrote Jones and his colleagues. “And any increases in the current rates of coastal retreat will have further ramifications on Arctic landscapes – including losses in freshwater and terrestrial wildlife habitats, and in disappearing cultural sites, as well as adversely impacting coastal villages and towns. In addition, oil test wells are threatened.”

Alaska Coastal Erosion2

In fact, in another recent study along the same stretch of the Beaufort Sea, Jones and his co-authors verified “disappearing” cultural and historical sites, including Esook, a turn-of-the-century trading post now part of the Alaskan seafloor and Kolovik (Qalluvik), an abandoned Inupiaq village site that may soon be lost. At another site, near Lonely, Alaska, Jones snapped a picture of a wooden whaling boat that had rested on a bluff overhanging the ocean for nearly a century. A few months later the boat had washed away to sea. This study was published in the journal Arctic.

Understanding contemporary erosion rates is important because Arctic climate change is leading to rapid and complex environmental responses in both terrestrial and marine ecosystems in ways that will almost certainly affect the rate and pattern of coastline erosion in the Arctic, the authors wrote. “For example,” said Jones, “the recent trends toward warming sea-surface temperatures and rising sea-level may act to weaken the permafrost-dominated coastline by ‘helping’ more quickly thaw ice-rich coastal bluffs and may potentially explain the disproportionate increase in erosion along ice-rich coastal bluffs relative to ice-poor coastal bluffs that we documented in our study.”

The authors also documented sections of coastline that eroded more than 80 feet during 2007. Interestingly, there were no westerly storm events during the summer of 2007, traditionally believed to be the drivers of coastal erosion in this region the Arctic. However, 2007 did boast the minimum arctic sea-ice extent on record and relatively warm ocean temperatures. The authors emphasized that monitoring of coastal erosion should continue to better understand the causes for these heightened erosion rates, particularly as Arctic regions are being targeted for additional hydrocarbon development.

Alaska Coastal Erosion

Original Article And Learn More, USGS

Climate change threatens life in Shishmaref, Alaska; CNN
“When the arctic winds howl and waves pummel the shore of this Inupiat Eskimo village, Shelton and Clara Kokeok fear that their house, already at the edge of the Earth, finally may plunge into the gray sea below. “The land is going away,” said Shelton Kokeok, 65, whose home is on the tip of a bluff that’s been melting in part because of climate change. “I think it’s going to vanish one of these days.”
A dozen Alaskan villages, including Shishmaref, are at some stage of moving because of climate-change-related impacts like coastal erosion and flooding…Around the world, as many as 150 million people may become “climate refugees” because of global warming, according to an Environmental Justice Foundation report, which attributes some of the moves to rising sea levels…”

Alaska Coastal Erosion
Photo source: USGS

Pondicherry-Tamil Nadu, South India; By Aurofilio Schiavina

After June 2002

Anthropogenic coastal erosion along the Pondicherry-Tamil Nadu coastline, South India

© By Aurofilio Schiavina

The town of Pondicherry lies on the eastern coast of the South Indian peninsula. About 100 km to the south of Pondicherry is the Cauvery delta, fed by the Cauvery River that flows from the west to east across the Indian peninsula depositing considerably large volumes of sand. The large input of sediment along the eastern coast of India resulted in the formation of large and wide sandy beaches, dunes and estuaries.

Two monsoon seasons drive the sand and sediment up and down the eastern coast of India. The south-west monsoon season lasts for about 8 to 9 months from March to October, and the north-eastern monsoon season lasts for about 3-4 months during the remaining winter months. It is estimated that during the SW monsoon about 0.5 to 1.0 million cubic meters of sand are driven northwards by the waves, winds and littoral currents. The situation reverses itself during the NW monsoon and about 0.1 – 0.2 million cubic meters of sand is driven southwards. This uneven movement of sand or littoral drift along the coast results in a net movement and transportation of sand towards the north.

In 1989, the Government of Pondicherry received funds for the development of a small commercial harbor near Pondicherry at the mouth of the Ariyankuppam River. The design included a 350 m long jetty and breakwater at the harbor entrance and a sand by-passing system to help mitigate the impacts of erosion that an artificial structure along the coast would cause to the north of the harbor. This region north of the harbor, near Pondicherry and Tamil Nadu is densely populated.

Unfortunately, Pondicherry harbor generated little revenue. This resulted in no available funding for the mitigation and sand by-passing system. Dredging occurs only when the harbor mouth gets choked with sand. This deepens the channel for the increasing number of fishermen who have adopted this harbor. Due to the lack of dredging, mostly as a result of the lack of political will and bureaucratic hurdles the sand by-passing system was not fully implemented. As a result, the breakwaters at the harbor entrance have interfered and interrupted the littoral drift causing severe and extensive erosion to the north of the harbor.

By the mid-late 1990s, the erosion of the Pondicherry coast was severe. Instead of utilizing the sand by-passing system, government agencies elected to armor the beach with large rocks, build a seawall, and construct several groins to protect the town. These measures did not address the root cause of the problem; the interruption of the littoral drift. As a result of the use of hard coastal protection measures (instead of sand by-passing), up to 10 km of beaches to the north of the harbor have completely been lost and signs of coastal erosion can be seen up to a distance of about 30 km. It is estimated that the erosion is advancing northwards at a rate of about 500 meters a year.

The erosion of this coast has resulted in the loss of beaches including 200 acres of coastal land and environment. Most importantly, erosion has destroyed the homes of poor traditional fishing families who live next to the sea. A government report states that about 35,000 fishing families are vulnerable to inundation from the sea. This land loss has severely affected their livelihoods as they use the beach space for all their activities. It has also caused saltwater intrusion into their aquifers, leading to shortages of drinking water.

Erosion from poorly planned engineering activities has extended into the neighboring state of Tamil Nadu causing inter-state problems. The construction of more seawalls and groins is being considered by the government, but informed citizens and environmental groups such Pondy Citizens’ Action Network (Pondy CAN!) are trying to put an end to this man-made disaster. These groups are asking the government to take all the required measures to restore this coastal environment without hardened beach structures.

The erosion of Pondicherry beaches is not an isolated case along the Indian coastline; it is estimated that the Indian coastline has already lost about 25% (1,500 km) of its beaches due to anthropogenic factors. It is hoped that reversing the erosion caused in Pondicherry and restoring this part of the coastline could serve as a model and example which could be replicated in other parts of this country and region.

Pondicherry Tamil Nadu Beach Erosion

PondyCan Organization

Indian Ocean Sea Level Rise Threatens Millions

Indian Ocean
This image shows the key player in the process, the Indo-Pacific warm pool, in bright orange. This enormous, bathtub-shaped area spans a region of the tropical oceans from the east coast of Africa to the International Date Line in the Pacific. The warm pool has heated by about 1 degree Fahrenheit, or 0.5 degrees Celsius, in the past 50 years, primarily because of human-generated emissions of greenhouses gases.I mage Source: NASA Earth Observatory

Excerpts;

Newly detected rising sea levels in parts of the Indian Ocean, including the coastlines of the Bay of Bengal, the Arabian Sea, Sri Lanka, Sumatra and Java, appear to be at least partly a result of human-induced increases of atmospheric greenhouse gases, says a study led by the University of Colorado at Boulder.

The study, which combined sea surface measurements going back to the 1960s and satellite observations, indicates anthropogenic climate warming likely is amplifying regional sea rise changes in parts of the Indian Ocean, threatening inhabitants of some coastal areas and islands, said CU-Boulder Associate Professor Weiqing Han, lead study author. The sea level rise, which may aggravate monsoon flooding in Bangladesh and India, could have far-reaching impacts on both future regional and global climate.

The key player in the process is the Indo-Pacific warm pool, an enormous, bathtub-shaped area of the tropical oceans stretching from the east coast of Africa west to the International Date Line in the Pacific. The warm pool has heated by about 1 degree Fahrenheit, or 0.5 degrees Celsius, in the past 50 years, primarily caused by human-generated increases of greenhouse gases, said Han…

Read Full Article, Science Daily

Article in, UC Arts and Sciences Magazine

A 500 million euros Plan to strengthen levees in France


Seawall, Courseulles-sur-mer, Basse Normandie. Photo source: ©© Olivier Engel

Un plan de 500 millions d’euros pour consolider les digues en France.

By Bertrand d’Armagnac, Le Monde.

Quatre mois et demi après la catastrophe provoquée par la tempête Xynthia en Vendée et en Charente-Maritime, le Gouvernement a annoncé ce mardi 13 juillet, la mise en place d’un “plan digues” destiné à mieux répondre aux risques de crues et d’inondations en France.

Présenté ce mardi en Conseil des ministres par le ministre du Développement durable, Jean-Louis Borloo, ce plan prévoit le renforcement de 1200 kilomètres de digues fluviales et maritimes.

Sur la période 2011-2016, l’Etat souhaite mobiliser environ 500 millions d’euros afin d’aider au confortement de 1 200 km de digues sur un parc de près de 9 000 km. Le plan, dont la mise en place est prévue dès 2010, fera l’objet, dans les mois à venir, d’une concertation visant à l’enrichir et à le préciser. Il reprend notamment des pistes lancées lors des auditions devant le Parlement, sur les causes de la tempête Xynthia.

Read Original Article, Le Monde


A plan of 500 million euros to strengthen the levees in France.
Google English Translation

Four and a half months after the disaster caused by storm Xynthia in the Vendée and Charente-Maritime, the French Government presented Tuesday, July 13, in Council of Ministers, proposals for the development of a “Plan Digues” intended to better respond to flood risk and flooding in France.

Over the period 2011-2016, the State wants to raise about 500 million euros to aid in reinforcement of 1,200 km of sea walls and levees, on a fleet of nearly 9000 km. The plan, whose implementation is planned from 2010, will be in the coming months, an action designed to enrich and to clarify that. It includes such tracks launched at the hearings before the Parliament on the causes of the storm Xynthia.

“The state of protection works, overall concern and the lack of a suitable project management, pose real problems today,” said French Minister of Ecology, Francois Borloo. The system devised by the Department of Ecology take into consideration sea walls and levees along coastlines and rivers, as well as the natural lines of defense such as dunes, lagoons and swamps.

It encompasses not only the upgrading of the park dykes and restructuring of its management, but also reducing the vulnerability of areas at risk and better use of weather forecasting and warnings.

The plan to establish by 2011 a list of high-risk flood areas, identified as priorities, which will trigger the diagnosis and the securing of levees and natural systems involved. However, certain protective structures require urgent action and therefore the initiation of work before the spring tides in August and September. This is the case of dams damaged by the storm Xynthia who are already the subject of work launched in March, which should lead to a consolidation before reliable high tides.

For other works, the identification process is being completed in respect of river levees, and will be completed by the end of 2010. The diagnostic techniques for detecting the most dangerous structures will be established by end-2010 for all works damaged by Xynthia and before the end of 2011 for the entire coastline. This diagnostic work will be done on the sea walls and levees between late 2010 and late 2011.

The organization of project management is another issue to be addressed urgently. In France, almost one third of the sea walls has no known owner or is in the hands of local residents or municipalities with insufficient means.

Devices are to be found in order to ensure that sea walls’ maintenance and repairs are completed specifically when faced with owners with reduced technical and financial capabilities, or if they are unknown. A working group of State and local Governments Representatives, is to make proposals on this topic by the end of 2010, including a better definition of the legal framework for community response.

Another element of the Plan: the urbanization of areas at high risk. A greater control of these areas, including the ban on further construction in low-lying areas, is now recommended by the Ecology Minister. In order to manage urbanization, plans to prevent natural hazards (NRPP) will be completed or be reviewed within a maximum period of three years.