16 自然和人为因素使得北非乍得湖严重干枯

DATE=4-19-01 
TITLE=SCIENCE REPORT - Lake Chad Shrinking 
BYLINE=Jerilyn Watson 

（Start at 1'01" ）This is Bill White with the VOA Special English Science Report. 
Scientists say there has been a （1）severe decrease in the amount of water in Lake Chad in northern Africa in the last thirty years. They report that nature and humans share equal blame for this loss. 
In Nineteen-Sixty-Three, the fresh-water lake covered twenty-five-thousand-square kilometers. Now the lake is only about five percent of that size. It measures only about one- thousand- three- hundred square kilometers in the dry season. 
Four nations surround Lake Chad. People in （2）Niger, （3）Nigeria, Chad, and （4）Cameroon use it for water, fish and plant life. 
Michael Coe and Jonathan Foley are water experts at the University of Wisconsin in Madison. They reported about Lake Chad in the Journal of Geophysical Research. They say the area has (4) suffered from a lack of heavy rain for more than thirty years. This has forced people to build systems to carry water to dry land. These irrigation systems further decrease the lake. 
Mister Coe says Lake Chad will be only a small body of water in the future. He says people still can get water from the lake to drink and for crops. But he says the lake will no longer (5) provide a healthy environment for fish and plant life. 
The researchers used a computer to study what caused the water loss. Their computer study (6) estimated the climate and amount of water in the area. The estimate started with the early Nineteen-Sixties. Then the researchers compared the estimates with the area's recorded climate and water supply for the same period. 
The computer study showed results similar to the recorded ones for the first twenty years. But there was a big change in the Nineteen-Eighties. At that time, the lake got smaller much faster than the computer research had estimated. 
The researchers say major irrigation systems were built in the Nineteen-Eighties. The systems took water from two rivers that flow into Lake Chad. The Chari and Logone rivers carry most of the water that enters the lake. The study showed the increased irrigation reduced the flow in the two rivers. Climate changes also were responsible for the reduction. Today the flow of the two rivers has been reduced by almost seventy-five (7) percent. 
Scientists say the problem is expected to worsen in the coming years as the population and demand for water continue to increase. 
This VOA Special English Science Report was written by Jerilyn Watson.
 
注释：
(1)		severe[ si5viE ]a.严厉的,剧烈的, 严重的
(2)	Nigeria[ nai5dViEriE ]n.尼日利亚(非洲中西部国家)
(3)	suffer[ 5sQfE ]v.遭受, 经历, 忍受vi.受痛苦, 受损害
(4)	provide[ prE5vaid ]v.供应, 供给, 准备, 预防, 规定
(5)	estimate[ 5estimeit ]v.估计, 估价, 评估n.估计, 估价, 评估
(6)	percent[pE5sent]n.百分比, 百分数