Category Archives: Erosion

Asymmetrical waves in barred beaches

waves
Photo source: ©© Tashland

Abstract; By Journal Of Integrated Coastal Management “Ondas assimétricas em praias com barra”

Natural beaches often present a breaker bar that significantly affect physical phenomena like, for example, wave transformation, wave reflexion, energy dissipation due to breaking and wave reforming into the trough region. These transformations are associated to nonlinear wave modifications.

In this work the oscillatory flow near the bottom of barred beaches is characterised. To achieve that purpose, the data obtained during two experiments were examined and processed: the data from a large-scale laboratory experiment carried out at the wave flume of the Polytechnic University of Catalonia (Barcelona, Spain) and the data from a nearshore field experiment, denoted by DUCK94, performed in a barrier island located in Duck (North Carolina, USA).

In the present analysis, we focus on the records provided by electromagnetic current meters placed near the bottom and at different cross-shore locations. The study undergoes through the identification of velocity and acceleration-skewnesses, which are recognised as forcing mechanisms capable to entrain and drive sediment transport. These characteristics are identified, and the cross-shore evolution of these parameters associated to wave propagation is assessed.

The results obtained for the two experiments are consonant, showing that nonlinear characteristics increase over the bar. In that region, one observes that velocity and acceleration-skewness coexist. This is evidenced through the study of the cross-shore evolution of some statistical moments and other simple parameters determined from the analysis of notable points in the velocity time series. The characteristics found in this work are important for sediment transport purposes, providing more insight about the effects that can cause sandbar migration and, thus, bed morphologic changes.

Original Article

Read Original Study, Portugese

Deforestation Along The Rio Xingu Shores, Brazil

brazil deforestation
Image source: ISS Crew Earth Observations experiment and Image Science & Analysis Laboratory, Johnson Space Center. The image was taken by the Expedition 29 crew / NASA

By William L. Stefanov, Jacobs/ESCG at NASA-JSC / Earth Observatory

The rainforest of South America, also known as Amazonia, has been undergoing a continual and accelerated conversion process into farmlands (including pasture for livestock) since the early 1960s.

This process has typically been achieved by clearing the forest using fire—“slash and burn”—followed by planting of crops. The generally infertile soils of this rainforest—the largest such forest on Earth—make sustainable farming difficult. This drives people to convert more forest into farmland. The area of clearing can be considerable, and since the deforested regions are easily identifiable and measurable from space, the rate of deforestation is likewise easy to track.

This astronaut photograph illustrates slash-and-burn forest clearing along the Rio Xingu (Xingu River) in the state of Matto Grasso, Brazil. The photo was taken from the International Space Station, a platform from which astronauts can capture images of the Earth from a variety of viewing angles. The perspective above shows both the horizontal position and the extent of the fire lines next to the river, while also providing a sense of the vertical structure of the smoke plumes.

Light colored areas within the river channel are sand bars, which show that the river is in its annual low-flow/low-water stage. For a sense of scale, the river channel is approximately 63 kilometers (39 miles) long in this view. Rivers are the natural highways in Amazonia, which may explain why the burning is occurring right next to the Xingu River, one of Amazonia’s largest.

In recent years, forest preservation has gained traction in the region as a result of new valuation of the ecosystem services provided by the forest, concerns about the impact of the burning on global climate change, and greater sensitivity to the ethnic and biological heritage of Amazonia.

Original Article, NASA

Belo Monte Dam, Xingu River, Brazil
The £7bn Belo Monte dam on the Amazon’s Xingu river is scheduled to start producing energy on 31 December 2014 and would be the second largest of its kind in Brazil and reputedly the world’s third largest.

A Giant Brought To Its Knees: The Atlantic Coastal Forest

Forests Soak Up Third Of Fossil Fuel Emissions

Victory For Burma Reformers Over Dam Project

burma
Sunset over Bagan, Myanmar (Burma). Bagan was the ancient capital of several ancient kingdoms in Burma and is located on the eastern bank of the Irrawaddy River.
The Irrawaddy River, flows from north to south through Burma (Myanmar). It is the country’s largest river and most important commercial waterway. Originating from the confluence of the N’mai and Mali rivers, it flows relatively straight North-South before emptying through the Irrawaddy Delta into the Andaman Sea. (Wikipedia).
The ruins of Bagan cover an area of 42 square km. The majority of its buildings were built in the 11th century to 13th century. It is estimated that as many as 13,000 temples and stupas once stood on this 42 square km plain in central Myanmar, and Marco Polo once described Bagan as a “gilded city alive with tinkling bells and the swishing sounds of monks’ robes”. Approximately 2,200 remain today, in various states of disrepair. Caption and Photo source: © Martin Sojka

Excerpts;

Activists and environmentalists notched up a rare victory in Burma when the president ordered the suspension of a huge Chinese hydropower project on the Irrawaddy river.

The $3.6 billion dam was being built at the head of Burma’s economically and ecologically significant Irrawaddy River, in a highly earthquake prone region.

It has been opposed by environmentalists and has been the reason behind a number of recent and rare protests.

President Thein Sein informed parliament on Friday that construction of the $3.6bn (£2.3bn) Myitsone dam should be halted because it was against the will of the people…

Read Full Article, Guardian UK

Chilean Patagonia: A Way Of Life Under Threat By Dams

Malaysia’s Borneo Lose Test Case Over Mega-Dam

$102 Million in Wetlands, Barrier Island Restoration Awards for Louisiana

louisiana-landloss
Grand Bayou, land loss. Photo source: ©© eustatic

By The Department Of Commerce

Acting Secretary of Commerce Rebecca Blank announced $102 million for three Louisiana projects in the Barataria and Terrebone basins, to restore deteriorated wetlands and barrier island habitats along the state’s coast. These awards are funded by the Coastal Wetlands Planning, Protection and Restoration Act (CWPPRA) program. U.S. Rep. Cedric Richmond, D-La., Louisiana Coastal Protection and Restoration Authority Director Garret Graves and Great Lakes Dredge & Dock Project Director Bobby Guichet also participated in the announcement.

Great Lakes Dredge & Dock and Weeks Marine have been contracted to restore beach, dune and marsh on Pelican Island in Plaquemines Parish, and West Belle Pass barrier headland in Lafourche Parish, respectively. The state of Louisiana will receive the third award to rebuild marsh and construct an 11,000-foot long protective ridge in the Bayou Dupont area in Jefferson Parish. The three projects will employ local citizens and generate further economic benefits for local businesses and coastal communities.

“Restoring wetlands and barrier islands and the habitat they support provides immediate local jobs and makes a long-term investment in the health of our fisheries and the resilience of our coastline,” Acting Secretary Blank said. “This restoration will pay dividends for those whose lives and livelihoods depend on sustainable Gulf fisheries and for all Americans who enjoy Gulf seafood.”

“If one block of New York City disappeared every hour the nation would be outraged. Well, Louisiana loses a football field of wetlands every hour, which is crippling to the state and the Nation. It affects our seafood supply, gas and oil reserves, and storm protection. Reversing this trend is a critical national priority, which is why it’s my fight,” Rep. Cedric Richmond said. “This is also why these grant announcements are so critical. I am pleased that Acting Secretary Blank and the National Oceanic and Atmospheric Administration within the Department of Commerce recognize the importance of New Orleans area coastal restoration efforts.”

At the event, Blank also outlined help the American Jobs Act would provide Louisiana – putting people to work and boosting businesses. The plan would provide a significant new tax cut for small businesses, make major reforms to unemployment insurance to help get more Americans back on the job, and it would put more money in the pockets of Americans by reducing payroll taxes paid by workers.

For Louisiana, the Jobs Act would mean:

80,000 firms receiving a payroll tax cut;
6,400 jobs supported for highway and transit modernization projects;
6,300 educators and first responders who get to stay on the job;
Help for 42,000 long-term unemployed workers; and,
A $1,400 tax cut for the typical Louisiana household.

The Jobs Act would complement the coastal restoration work funded by the awards announced by Blank today.

Currently, Louisiana accounts for nearly 71 percent of U.S. fisheries landings by weight from the Gulf of Mexico. Many species of finfish, shrimp, and crab depend on the wetlands of the Barataria Basin for habitat during their life cycles.

But with one of the highest rates of wetlands loss in the world, the Louisiana coastline has deteriorated extensively over the last 80 years, losing more than 420 square miles of wetlands to open water in the Barataria Basin alone.

These losses are largely the result of long-term, man-made changes, including the construction of levees, which have cut off the natural flow of nourishing sediments.

Although the area sustained damage as a result of the Deepwater Horizon oil spill in 2010, the three projects in Bayou Dupont, Pelican Island and West Belle Pass were designed prior to the spill and are intended to address long-standing issues rather than the direct repercussions of the spill.

Restoring the wetlands and barrier islands will also increase protection for Louisiana’s people and property, as well as one of America’s richest fisheries. By absorbing hurricane storm surge, rebuilt wetland and barrier island areas will help protect Orleans and Jefferson parishes, two of the top-five most densely populated counties in the Gulf coastal zone.

These three projects continue NOAA’s long-term investment in the Louisiana coastline through the CWPPRA program. Enacted in 1990, CWPPRA has designed and funded 151 coastal restoration or protection projects benefiting more than 110,000 acres in Louisiana.

Most recently, NOAA has been working to rebuild the Barataria Basin barrier island chain, constructing two barrier islands, Chaland Headlands and Pass la Mer to Grand Bayou Pass, in addition to Pelican Island.

Original Press release

Atlas of Shorleine Changes In Louisiana, 1853-1989, USGS

On The Elwha, A New Life When The Dam Breaks

elwha-dam-before-usgs
Elwha Dam, before. Photo source: National Park Services.

Excerpts; By The Smithsonian

The nation’s largest and most ambitious dam removal will begin this month, when workers start demolishing two antique dams on Washington state’s Elwha River. The Elwha has been cut off from its source in the Olympic Mountains for almost a century, and its once rich salmon runs have dwindled to practically nothing…

Read Full Article, The Smithsonian

Biggest dam removal in U.S. history will look like this, Los Angeles Times
Nobody figured the largest dam removal project ever attempted in the U.S. was going to be easy — or fast. In fact, though the official demolition started Saturday, it will take two or so years to completely remove both dams on the Elwha River in Washington state, engineers say.

Olympic National Park

Elwha Dam Removal Project


Elwha Dam Removal Begins—Long-Planned Project Will Restore Ecosystem, Salmon Runs: USGS

By Jonathan A. Warrick / USGS

The largest dam-removal project in U.S. history—the Elwha River Restoration Project—commenced during the second week of September 2011, when National Park Service contractors began to dismantle two dams on the Elwha River in Washington State. The 32-m-tall Elwha Dam and the 64-m-tall Glines Canyon Dam, completed in 1913 and 1927, respectively, have been blocking the natural supply of sediment to the lower river and coast and severely limiting salmon and steelhead spawning for nearly a century. In a ceremony celebrating the beginning of the Elwha River restoration, Secretary of the Interior Ken Salazar praised the project, saying, “America’s rivers are the lifeblood of America’s economy—from the water for farms that produce our food to the fish and wildlife that sustain our heritage.” He added that restoration will help support the culture of the Lower Elwha Klallam Tribe, who have lived along the river for centuries.

elwha-dam-2-usgs
Elwha Dam, removal started. Photo source: National Park Services.

The Elwha River Ecosystem and Fisheries Restoration Act, passed by Congress in 1992, directed the Secretary of the Interior to study ways to fully restore the Elwha River ecosystem and native anadromous fisheries. (Anadromous fish, such as salmon and steelhead, spend most of their lives at sea but return to freshwater to breed.) In 2000, the federal government purchased the dams and related facilities, and on Saturday, September 17, 2011, removal of the dams began. News of this event appeared throughout the national media, including the New York Times, the Washington Post, National Public Radio, and the Associated Press.

To kick off the unprecedented restoration, the Olympic National Park and the Lower Elwha Klallam Tribe sponsored a week of festivities titled “Celebrate Elwha.” The U.S. Geological Survey (USGS), which has a long history of Elwha River research and monitoring (see related Sound Waves articles “Studying the Elwha River, Washington, in Preparation for Dam Removal” and “Dam Removal on the Elwha River in Washington—Nearshore Impacts of Released Sediment”), participated in numerous Celebrate Elwha events. Concurrently, several USGS research groups conducted their final “pre-removal” surveys of the conditions of the river, the reservoir sediment, the river-channel morphology, and the coastal setting at the river mouth. The multiagency activities of September 2011 helped to inform colleagues, managers, and the general public about the restoration of the Elwha River, as well as providing the final observations of the river in its dammed state.

Among the week’s activities was a 2½-day Elwha River Science Symposium, led by USGS scientist Jeff Duda of the USGS Western Fisheries Research Center (WFRC). The symposium was attended by more than 350 participants and included numerous scientific and multimedia presentations. Keynote speakers included experts in river and salmon restoration and people deeply knowledgeable about the Elwha: James Karr (Professor Emeritus in the University of Washington’s School of Aquatic and Fishery Sciences), Thomas Lovejoy (Professor of Environmental Science and Policy at George Mason University and founder of the Public Television series Nature), Yvon Chouinard (global conservationist and founder of the outdoor clothing and equipment company Patagonia), Martin Doyle (Professor of River Science and Policy at Duke University), Dick Goin (resident with 7 decades of experience observing the Elwha River and its salmon populations), Gordon Grant (Research Hydrologist at the U.S. Forest Service’s Pacific Northwest Research Station and Professor [Courtesy] in the Department of Geosciences at Oregon State University), David Montgomery (Professor in the Department of Earth and Space Sciences at the University of Washington), and Thomas Quinn (Professor in the School of Aquatic and Fishery Sciences at the University of Washington).

On the first evening of the Elwha River Science Symposium, USGS geologist Jonathan Warrick gave a public lecture along with reporter Lynda Mapes (Seattle Times) and documentary filmmaker and photographer John Gussman (Doubleclick Productions). During the symposium sessions, findings on baseline conditions in the Elwha River watershed and expected outcomes of dam removal were presented by USGS scientists from several centers, including Amy Draut (Pacific Coastal and Marine Science Center [PCMSC]), Guy Gelfenbaum (PCMSC), Chris Konrad (Washington Water Science Center [WWSC]), Chris Magirl (WWSC), Pat Shafroth (Fort Collins Science Center), Steve Rubin (WFRC), and Jonathan Warrick (PCMSC). Several other USGS scientists were noted for their early and important work on the Elwha River, including Mark Munn (WWSC) and the late Dallas Childers (formerly with the USGS Cascades Volcano Observatory). The Elwha River Science Symposium ended with a 3-hour cruise from Port Angeles to the mouth of the Elwha River for 100 attendees. Jonathan Warrick and Ian Miller (University of California-Santa Cruz and Washington SeaGrant) served as co-emcees, providing interpretations and background information during the cruise.

Perhaps the highlight of the week was the ceremony held on and adjacent to the Elwha Dam on September 17, 2011. Speakers at this event included Secretary of the Interior Ken Salazar, Washington Governor Chris Gregoire, Lower Elwha Klallam Tribal Chairwoman Frances Charles, U.S. Congressman Norm Dicks, U.S. Senators Patty Murray and Maria Cantwell, Assistant Secretary for Indian Affairs Larry Echo Hawk, Bureau of Reclamation Commissioner Michael Connor, and National Park Service Director Jon Jarvis. Music and dance were provided by several groups, including the Klallam Drum and Dance Group. Three USGS scientists—Jeff Duda, Pat Shafroth, and Jonathan Warrick—were among the half-dozen docents who welcomed attendees and provided interpretations for the day’s events. The ceremony ended with the removal of part of the Elwha Dam by an excavator with a gold-painted bucket. The excavator tore apart a section of the dam to the sounds of celebration drumming and singing by the Klallam Drum and Dance Group.

While the week ended with concerts, parties, public hikes into the Elwha River watershed, and storytelling and film events, Amy Draut, Josh Logan (USGS PCMSC), and Toby Minear (USGS, California Water Science Center) finished the final pre-removal surveys of the river channel and reservoir sediment. These surveys will help document how the Elwha River channel changes after dam removal.

The commencement of dam removal begins a 2½-year process of taking down the Glines Canyon and Elwha Dams to help restore the once-vibrant salmon runs on the Elwha River. It also launches a new and important phase of scientific investigation, as researchers seek to describe and understand the changes that will occur to the ecosystems and natural resources of the Elwha River watershed and coast during and after dam removal.

elwha-dam-removal
Photo source: National Park Services.

Malaysia’s Borneo Tribes Lose Test Case Over Mega-Dam

bakun-dam-malaysia
Indigenous people shown leaving Bato Kelau village for the last time due to construction of the Bakun Dam in Malaysia. Photo source: ©© International Rivers

Excerpts; AFP

A 12-year legal battle by indigenous tribes in Malaysia against their ancestral land being seized to build a mega-dam on Borneo island ended in defeat Thursday in the nation’s top court.

Indigenous people present at the court said they were devastated by the ruling, while activists said it could encourage the government to requisition more land on Malaysia’s part of Borneo and create “internal refugees.”

bakun-dam-malaysia
The Bakun Dam in Malaysia. Photo source: ©© Mohamad Shoox

Read Full Article, AFP

Bakun Dam, Wikipedia

Chilean Patagonia: a Way of Life Under Threat by Dams

The Problems With Dams
Dams block sediments going to the ocean, which implies accelerated erosion.

Aerial Photos of Outer Banks Show Coastal Damage from Hurricane Irene

location-map
Each location includes photos and/or photo-pairs showing changes that occurred during Hurricane Irene. The green line shows Hurricane Irene’s track.

By USGS

A series of before and after aerial photos of the Outer Banks show the impact of Hurricane Irene on the coastline, highlighting several breaches that severed a state highway and moved large volumes of sand inland.

The series features five photo pairs that show coastal change in areas from Cape Lookout to Oregon Inlet.

Hurricane Irene made direct landfall near Cape Lookout on August 27. Because of the right-angle shape of the Outer Banks, barrier islands facing southeast experienced different coastal changes than those islands facing east.

The southeast-facing coast, from Cape Lookout to Cape Hatteras, was exposed to waves and surge from the ocean. Photographs of Ocracoke Island show large volumes of sand removed from the beach system and deposited over roads and grass marshes. Flooding by storm surge in these areas was minimal however, as surge crested above dunes in only limited locations.

The east-facing coast, from Cape Hatteras to Oregon Inlet, also experienced waves and surge from the ocean, but surge was higher in the sound. Sections of Rodanthe and Pea Island National Wildlife Refuge were exposed to storm surge in Pamlico Sound of roughly six feet that contributed to the carving of channels through the island that breached a state highway at several locations. A total of five breaches were cut through the coastal landscape between Cape Hatteras and Oregon Inlet.

“Such multiple breaches, or new inlets, cut through the Outer Banks could take weeks to months to close on their own,” said Asbury (Abby) Sallenger, a U.S. Geological Survey oceanographer. “And without intervention like pumping sand, some could even persist indefinitely depending on the channel’s cross-section and the amount of water flushed through it on every tide.”

Three days after the landfall of Hurricane Irene, USGS scientists acquired detailed information of coastal change through aerial photography and an airborne lidar survey mission conducted with the National Oceanic and Atmospheric Administration.

Lidar, light detection and ranging, is a remote-sensing tool attached to an aircraft that uses laser pulses to collect highly detailed ground elevation data. Information obtained from the surveys allow scientists to discern the degree of changes to beaches and coastal environments and determine how much the land has eroded and where new inlets have cut through. The photo and lidar information should be useful in mitigation and restoration efforts like rebuilding N.C. Highway 12, which was severed in several locations by breaches cut through the barrier islands by Hurricane Irene.

Data acquired will also be used to make more accurate predictive models of future coastal impacts from severe storms and identify areas vulnerable to extreme coastal change.

outer banks
Oblique aerial photograph of Pea Island National Wildlife Refuge, NC, looking north along the coast on August 30, 2011, three days after landfall of Hurricane Irene. Caption and photo source: USGS

Original Article

Hurricane Irene Opens New Inlets on Hatteras Island

By Rob Young and Andy Coburn, Program for the Study of Developed Shorelines, Western Carolina University

Personnel from the Program for the Study of Developed Shorelines (PSDS) are actively surveying the North Carolina coast following the passage of Hurricane Irene. Center Director Dr. Rob Young completed a surveillance flight of the northern Outer Banks Sunday morning and filed the following brief report of storm impacts:

1) In general the storm did little damage to ocean front property along the northern Outer Banks. Some dune scarping is visible, but storm surge was less then expected. Even so, Hurricane Irene has opened a new inlet just south of the freshwater ponds on Pea Island National Wildlife Refuge on Hatteras Island [Images IreneInlet1-3.jpg] (lat:35.684185, lon:-75.482329). The inlet is not as large as the so-called “Isabel Inlet”, but at flight time there was continued tidal exchange and filling in the inlet will require some time. There is also a small breach of the island just north of Rodanthe (MirloInlet.jpg) in the Mirlo Beach area (lat 35.607286, lon: -75.465431). Maintaining Highway 12 in light of even small storms like Hurricane Irene has become an unending challenge for NCDOT. It certainly makes one wonder about the planned replacement of the Bonner Bridge. Even if we can build an immovable Bridge, will there be a road left to connect to?

2) The $30+ Million beach nourishment project at Nags Head has survived the storm, although there certainly has been some loss of sand along the beach. The degree of loss is difficult to assess “on the fly” from the air. PSDS Associate Director Andy Coburn flew the beach on August 25, two days before the hurricane. Before images of the Nags Head project are currently available at https://picasaweb.google.com/psdspix and after images will be available at psds.shutterfly.com on Monday. In our judgment, Hurricane Irene would not have caused significant damage to any properties, with or without the new beach.

3) The primary impact from Hurricane Irene to the North Carolina Outer Banks was from significant soundside flooding impacting many areas of Duck, Kitty Hawk, Collington Village, Roanoke Island, and others. Much of this water has filled natural swales and dips on the backside of the islands, and will be around for some time.