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本校近期卓越研究成果： Science, 3/14/2008
地科院 - 趙丰院長, 博士生伍允豪, 碩士生李毅翔
"Impact of Artificial Reservoir Water Impoundment on Global Sea Level"
(Science, 3/14/2008)
B. F. Chao, Y. H. Wu, Y. S. Li
College of Earth Sciences,
National Central University, Taiwan
The concept is quite simple: We know that the global sea level (GSL) has been rising slowly at 1.8 mm/year over the past century (and is quickly accelerating in the last decade.) We also know that human have been building many reservoirs on land impounding large quantity of water behind artificial dams (water that would otherwise run-off to the ocean), especially since after WWII. The reservoirs thus have had a negative impact on the GSL rise – in other words, making the GSL rise not as fast as it should have been if only due to all the natural causes, including thermal expansion of ocean water, melting of land ice in the form of glaciers and Antarctica + Greenland ice sheets, etc., which are, in turn, caused by global warming. The question, then, is by how much.
Our study, by painstakingly compiling various data sources and documents of world's artificial reservoirs and reconstructing the history of the water impoundment thereof, shows that a total of ~10,800 km3 of water has been impounded on land to date, reducing the magnitude of GSL rise by 3 cm. This is indeed significant, for example, compared to the ~10 cm GSL rise observed over the past half century, which means the “true” GSL rise should have been 13 cm during this time if not for the artificial reservoirs.
The IPCC 2007 Climate Change report indicated that, after summing up all the known natural causes mentioned above, scientists are still short of explaining fully the observed GSL rise; so the (man-made) reservoir impact actually makes the situation even worse – or more difficult to explain.
On the side, good news and bad news – The good news is that, yes, it is possible to slow down the GSL rise by building more dams. The bad news is that this is not the point, because that does not solve any real problem. -- The main problem we face today is not the GSL rise itself, but the CAUSES of the GSL rise which serves as an unmistakable indication of the real problem behind – the global climate change. The latter is what makes this study more intriguing.
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