英语翻译Scientists say there has been a severe decrease in the a

英语翻译
Scientists say there has been a 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 1963 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 Niger,Nigeria,Chad,and 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 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 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 provide a healthy environment for fish and plant life.The researchers used a computer to study what caused the water loss.Their computer study estimated the climate and amount of water in the area.The estimate started with the early 1960s.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 1980s.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 1980s.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 percent.
Scientists say the problem is expected to worsen in the coming years as the population and demand for water continue to increase.

科学家说有一个严重的水量减少在非洲北部的查德湖在过去30年.他们报告说,自然和人类承担相同责任对于这个损失.
1963年,淡水湖覆盖二万五千平方公里.现在湖是只有约百分之五的大小.它的措施只有大约一千三百平方公里在旱季.
四个国家围绕乍得湖.人们在尼日尔、尼日利亚、乍得和喀麦隆用于水、鱼类和植物的生命.
迈克尔·科和乔纳森·弗利是水专家麦迪逊威斯康辛大学.他们报导乍得湖《地球物理学研究杂志》上.他们说这个区域一直苦于缺少的大雨超过30年.这迫使人们去构建系统携带水干燥的土地.这些灌溉系统进一步降低湖.
Coe说乍得湖先生将只有一个小的未来.他说,人们仍然可以让水从湖边喝水和农作物.但他说,湖将不再提供一个健康的环境,鱼和植物的生命.研究人员利用电脑来研究什么导致了水的损失.他们的计算机研究估计气候和数量的水在该地区.估计1960年代初开始的.然后研究人员比较了与该地区的估计记录气候和水供应同一时期.
计算机研究显示结果类似于记录的第一个二十年.但是有一个很大的变化在1980年代.当时,这个湖有较小的速度远远超过了计算机的研究估计.
研究人员说主要的灌溉系统都是在1980年代建造的.该系统把水从两条河流,流入乍得湖.Chari和Logone的河流携带大部分的水进入湖.研究显示增加灌溉减少了两条河流的流量.气候变化也负责减少.今天,