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West facing windows can be a big source of heat, first measure which you...
Why all these are not applicable to Tuticorin port or the one planned in AP or WB ?
What an eye opener! As an environmental engineer,disposal of sanitary napkins has always been a concern during waste...
Extinct species: Not only have salmon populations been decimated, but entire stocks have disappeared. Prior to the 20th century, the Columbia River in the us Pacific Northwest supported some 200 distinct stocks of the fish. Today, 69 stocks have disappeared with another 75 on the brink of total extinction. Moreover, the presence of salmon across the stretch of the river has been reduced to 10-30 per cent of their original distribution.
A study in 1992, titled Pacific Salmon at the Crossroads , identified 214 wild spawning Pacific salmon stocks that were at risk of extinction, including 17 stocks that were already extinct. Though there are only five original species of salmon in the Pacific -- Chinook, Sockeye, Coho, Pink and Chum -- that face the threat of extinction, there are hundreds of other stocks with distinctive features which can be included in the esa .
As of today, there are no indigenous salmon runs in rivers draining into Lake Ontario in Canada. Neither are there any Atlantic salmon in the large rivers of the European Atlantic coast -- the Thames, Rhine, Seine or Elbe. In fact, the salmon has disappeared from more than 142 rivers around the Atlantic in the last century. To a query sent by Down To Earth , Henning Roed, marine coordinator, wwf -Norway, writes: "About 100 years ago, there were approximately 40 Swedish wild salmon rivers in the Baltic area. Today there are only 12."
Toppling the dams: The us led the world in dam-building -- harnessing rivers for a variety of purposes, including hydropower, irrigation, flood control and water storage. The us Army Corps of Engineers has catalogued approximately 75,000 dams greater than five feet along the waterways of the United States. Secretary of the Interior, Bruce Babbitt, recently observed, "that means that, on an average, we have constructed one dam every day since the signing of the Declaration of Independence (July 4, 1776)."
Today, the us views dams as the biggest menace to river ecology, wildlife, aquatic habitat of fish and ultimately humans. Recent research has also thrown light on the immense damage dams cause to the universal food chain by disturbing the breeding habitats of fish. The resulting alarm has given rise to a growing demand across usa and Europe to raze the existing dams (see box: The French crusade ).
Ironically, the us -- which had over the past 100 years championed the cause of dam-building -- is now ordering their destruction (see box: On the hit list ). The most sensational being the decommissioning of the Edwards Dam. Built across the Kennebec River in Maines, the 280 m high dam was destroyed in July 1999. The Kennebec ran free on its pre-determined journey to the Atlantic after 162 years of confinement.
Return of salmon: The opinion against dams is so strong in the us that several of these concrete giants, from California to Connecticut, have been demolished in the past four decades (see map: Down with the dams ). It should not take long to see results.
On the Butte Creek in northern California, removing three dams beginning in 1997 allowed the salmon run to jump from zero to 20,000. Those numbers have environmentalists and fisherfolk eyeing dams in the Olympic Peninsula, where dozens of populations of salmon are endangered or extinct. Another instance is the Edwards dam, which, prior to its demolition, was taking a huge toll of the Atlantic salmon population by flooding their habitat and preventing migration. The dam's demolition, besides providing respite to the salmon, also benefited the population of nine other species of migratory fish, including the American shad, striped bass, Atlantic sturgeon and alewives.
The Quaker Neck Dam on the Neuse River in North Carolina, for example, came down in 1997-98 and today the bass and striped shad are already running free in the river.
Cost of pulling down dams: The debate on the cost for dismantling the dams has been raging for several decades and it's only recently that some dams have been decommissioned. "Dam breaching used to be laughed at," says Chris Zimmer of the Save Our Wild Salmon Organisation, a us -based environmental group, "but now it is a definite possibility."
Recently, reports from the Drawdown Regional Economic Workgroup ( drew ) -- a us -based committee comprising economists and analysts from the government, universities and the private sector -- estimated the direct costs of removing the four Snake River Dams, owned by the Army Corps of Engineers. The cost stands between us $800 million to us $1.1 billion.
In usa , the river conservation organisation American Rivers released the cost figures for destroying the Elwha and Glines Canyon Dams (owned by James River Corporation/ Daishowa Corporation) on the Elwha River in Washington. It quoted us $113 million.