San Francisco Chronicle/Science, Nate Seltenrich, 12/15/12. "San Francisco Bay sand mining alarms conservationists."
 |
| Our coastal erosion is from more than natural causes |
Partly as a result of sand mining, the 10-mile stretch between southern Ocean Beach and Point San Pedro near Pacifica is eroding faster than any other section of coastline in California, the geological survey says.
.... Using suction dredges mounted on 200-foot barges, sand miners intercept much of this material before it can leave the bay, reducing the sediment available to buffer and restore coastal beaches, the geological survey found. The mined sand is used in ready-mix concrete and asphalt destined for roadways, bridges, parking lots and buildings.
.... ".... a 2010 study by Barnard found that from 1997 to 2008, only 15
percent of the volume extracted from five lease areas was naturally
replenished. In recent decades, the addition of dams, wetland
development and flood-control projects upstream has significantly
restricted the flow of sediment to the bay." Read article.
Reference - U.S. Geological Survey, Point San Pedro.
Reference - U.S. Geological Survey, Point San Pedro.
15 comments:
Where is the outrage by ian and the beach coalition?
This is breaking news, San Francisco and our city should be paying attention.
Not sure why you would redirect your comment to an individual, and civic organization that does what it can to keep the coastal landscape clean, Anonymous 10:19 AM.
I'm outraged that while people are proposing "managed retreat" as a solution to our eroding beaches and bluffs, the sand mining companies are keeping sand from being deposited on our beaches and are making our problems worse, all for profit. If Pacificans are not outraged by this, we deserve what we get - more buildings being destroyed by increasing coastal erosion.
Outrage or latest enviro target? It's just one factor according to one report. Maybe the real outrage is that someone is making money, you know the P-word, profit. More info is needed.
"Just one factor" doesn't make it any less important. Everything is "just one factor." Aren't you bothered by the fact that sand mining is contributing to the erosion of Pacifica beaches?
I don't know that it is contributing, or if it is, how much. Even the USGS scientist whose work is cited in the article says it's only one factor and he doesn't quantify the contribution. So, no, until more evidence is found, I'm not going to rush to judgement. And since the enviro stewards, Baykeeper, has already filed suit in federal court, I'm sure all kinds of evidence will be made public. Til then, there just aren't enough facts upon which to base an informed opinion.
"... there just aren't enough facts upon which to base an informed opinion." Anonymous 9:02 PM.
With regard to sand mining, along with other bay/ocean changes, here's some facts from the article:
"The new leases allow the two companies to extract a total of 2 million tons of sand from the bay floor annually, a 43 percent increase over the 2002-07 average of 1.4 million tons. ... However, a 2010 study by Barnard found that from 1997 to 2008, only 15 percent of the volume extracted from five lease areas was naturally replenished."
Personally I find such seemingly significant information worth noting. And it seems so did the Chronicle science journalist. But as you have suggested, we'll see.
The information you're looking for is right there in the article.
"Dredge mining of shoals near Angel and Alcatraz islands and throughout Suisun Bay is robbing the bay of sand that keeps San Francisco's Ocean Beach from eroding, according to new research by the U.S. Geological Survey.
"Partly as a result of sand mining, the 10-mile stretch between southern Ocean Beach and Point San Pedro near Pacifica is eroding faster than any other section of coastline in California, the geological survey says.
"... Patrick Barnard [is] a scientist at the geological survey and lead author of a number of studies on the topic, including one published this month in the journal Marine Geology.
"... a 2010 study by Barnard found that from 1997 to 2008, only 15 percent of the volume extracted from five lease areas was naturally replenished."
It's a factor and that's what the article is saying. Barnard from USGS says "It's really hard to quantify the impact of the mining, but it's safe to say it is a factor." Barnard also mentions in his 2010 study the role played in recent decades by dams, wetland development and flood-control projects upstream in restricting the natural flow of sediment to the Bay. Sediment is being lost and sand mining is a factor. One of several factors and not quantified individually although he does state that only 15% of the volume taken from the 5 lease areas was replenished. In addition to the man-made activities listed above, climate change and sea-level rise also earned a mention for their role in accelerated erosion but there's not much we can do about Mother Nature.
I just read the article, and although I'm not exactly "outraged", I am intrigued to learn that some of our erosion problems may be due to activities in the bay. It seemed like our erosion was happening too fast to be from sea level rise alone. This is important information for Pacificans and appreciate that the article was posted here.
Well, this contradicts all other causes of beach erosion that the enviro wackos have put out to be fact. I am so confused.
They have been dredging out the shipping channels for years. They do this in every port city.
Our city is too broke to pay attention.
It's the City Council's fault.
duh
It doesn't contradict anything. It's another cause of beach erosion. If you're confused, you're not very bright.
Post a Comment