深山蘭

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阿斯旺水壩的影響和三峽大壩

作者：深山蘭於 2014-8-9 01:56 發表於最熱鬧的華人社交網路--貝殼村

作者分類:談天說地|通用分類:政經軍事|已有2評論

關鍵詞：三峽大壩, 阿斯旺, false, 影響

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阿斯旺水壩的影響和三峽大壩

埃及的阿斯旺水壩修建於1970年。它建成之後，產生了許多事先預料不到的結果。水利和地質學家們在課本上總結說：

The Aswan High Dam of the Nile provides a good example of the many consequences of modifying a river system. For centuries, the Nile River has been the sole source of life in Egypt. The principal headwaters of the Nile are located in the high plateaus of Ethiopia. Once a year, for approximately a month, the Nile used to rise to flood stage and cover much of the fertile farmland in the Nile Delta area. The Aswan High Dam, completed in the summer of 1970, was to provide Egypt with water to irrigate 1 million acres of arid land and generate 10 billion kilowatts of power. This ,in turn, was to double the national income, and permit industrialization. The dam, however, destroyed the equilibrium of the Nile, and many unforeseen adjustments in the river resulted. This is what happened.

The Nile is not only the source of water for the delta. It is also the source of sediment. When the dam was finished and began to trap sediment in a reservoir, Lake Nasser, the physical and biological balance in the delta are was destroyed. Without the annual 「gift of the Nile」, the delta coastline is now exposed to the full force of marine currents, and wave erosion is eating away at the delta front. Some parts of the delta are receding several meters a year.

The sediment previously carried by the Nile was an important link in the aquatic food chain, nourishing marine life in front of the delta. The recent lack of Nile sediment has reduced plankton and organic carbon to a third of the former levels. This change either killed off or drove away sardines, mackerel, clams, and crustaceans. The annual harvest of 16000metric tons of sardines and a fifth of the fish catch have been lost.

The sediment of the Nile also naturally fertilized the flood plain. Without this annual addition of soil nutrients, Egypt』s 1 million cultivated acres need artificial fertilizer.

The water discharged from the reservoir is clear, free of most its sediment load. Without its load, the discharged water flows downstream much faster and is vigorously eroding the channel bank. This scouring process has already destroyed three old barrier dams and new barrier dams between Aswan and the ocean must be built at a cost equal to one-fourth the cost of the Aswan Dam itself.

The annual flood of the Nile was also important to the ecology of the area, because it washed away salts that formed in the arid soil. Soil salinity has already increased, not only in the delta, but throughout the middle and upper Nile area. Unless corrective measures are taken (at a cost of over $1 billion), millions of acres will revert to desert within a decade.

The change in the river system has permitted double the cropping, but there are no periods of dryness. The dry seasons previously helped limit the population of bilharzias, a blood parasite carried by snails, which infects the intestinal and urinary tracts of humans. One out of every two Egyptians now has the infection, and causes a tenth of the deaths in the country.

Problems have also occurred in the lake behind the dam. The lake was to have reached a maximum level in 1970, but it might actually take 200 years to fill. More than 15,000,000 m3 of water annually escaped underground into the porous Nubian Sandstone which lines 480 km of absorbing an almost unlimited quantity of water. Moreover, the lake is located in one of the hottest and driest places on the earth, and the rate of evaporation is staggering. A high rate was expected, but additional losses from transpiration by plants growing along the lakeshore and increased evaporation from high winds have brought the total loss of water from the lake to nearly double the expected rate. This loss equals half the total amount of water that once was 「wasted」, flowing unused to the ocean.

W Kenneth Hamblin：The Earth』s Dynamic systems (Four Edition) 1985版.第10章River Systems

我選擇了幾段（有的段沒有翻譯），大意翻譯如下：

尼羅河不僅是三角洲水的來源，也是沉積物的來源。當大壩完工後，開始攔截沉積物在水庫中，三角洲的物質和生物上的平衡機制被打破了。沒有了一年一度的「尼羅河禮物」，三角洲的海岸線完全暴露在強勁的洋流面前，三角洲某些地方的海岸線每年後退數米遠。

以前尼羅河帶來的沉積物是水生物食物鏈的重要環節，滋養了三角洲附近的海生物。最近缺少尼羅河的沉積物，已經導致了浮游生物和有機碳減少到了過去三分之一的水平。這樣的變化不是滅絕了或者趕走了沙丁魚、mackerel 、貝類和甲殼類生物。年捕撈16000噸的沙丁魚和五分之一的魚類捕撈量已經消失了。

尼羅河的沉積物也給泛洪平原施肥，沒有了這些每年的額外肥料，埃及1百萬英畝的農田需要人工施肥。

尼羅河每年一度的洪水泛濫對於該地區的生態也是非常重要的，因為洪水沖刷走了在乾旱土壤里沉積的鹽分，現在三角洲的鹽分已經增加了，並且還在上部和中部尼羅河地區也是一樣的。除非採取適當的措施（代價超過10億美元），1百萬英畝的農田將在未來幾十年內重新返回成荒漠。

河流系統的變化使得農業收成翻倍，但也使得乾旱季節消失了。以前乾旱季節限制了一種攜帶血吸蟲的螺的數量。這種血吸蟲感染人的腸道和泌尿系統。現在每兩個埃及人中就有一個感染了血吸蟲，這佔了全國死亡原因的十分之一。

問題也發生在大壩後面的庫區。湖面在1970年達到最高水平，在未來200年的時間內，庫區會被淤平。庫區西岸480公里長的地區是多孔的怒比亞砂岩。每年有一千5百萬立方米的水滲到這些地下砂岩里。這些砂岩吸水的能力幾乎是沒有限制的。另外，庫區是位於地球上最乾旱和炎熱的地區之一，蒸發率是令人吃驚得高。現在湖邊生長的植物的蒸騰作用和高速的風增加的蒸發量使得湖區水的損失超過了原來期待值的一倍。這個數量等於該河每年注入海洋的流量的一半。人們通常認為那是「浪費掉了」的水量。

這些知識在1985年就寫入了課本。這些後果，當時已經很清楚了。人們通常會說「當事後聰明人很容易（It is easy to be wise after the event）」，而中國在修建三峽水庫前吸取了這些教訓嗎？根本沒有！何況，中國人自己早就搞清楚了大型水庫會誘發地震，加劇庫區某些地區的山體滑坡，等等，等等。

對此，中國人去搞什麼重新發現！就算如此，那些知識也是根本不起任何作用的。

既然任何知識對於中國人來說，幾乎不起作用，那麼，他們遭到大自然的報復，就是一種報應了。怪誰呢？「吾誰欺？欺天乎？」2000年前劉秀的話，用到此處，不是很合適嗎？

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