求一篇获取信息的途径的英语作文,300字左右就好了.

求一篇获取信息的途径的英语作文,300字左右就好了.

Life on earth depends on waterand there is no substitute for it. The current assumption is that our basic needs for water-whether for drinking agriculture industry or the raising of fish--will always have to be met. Given that premise there are two basic routes we can go. more equitable access to water or more drastic engineering solutions.Looking at the engineering solution first a lot of my research concentrates on what happens to wetlands when you build dams in river basins particularly in Africa. The ecology of such areas is almost entirely driven by the seasonal change of the river--the pulse of the water. And the fact is that if you build a dam you generally wreck the downstream ecology. In the past such problems have been hidden by a lack of information. But in the next century governments will have no excuse for their blissful ignorance.The engineers ability to control water flows has created new kinds of unpredictability too. 'Dams in Africa have meant fewer fish less grazing and less floodplain agriculture--none of which were anticipated. And their average economic life is assumed to be thirty years. Dams don't exist for ever but what will replace them is not clear.The key issue in any discussion of water is money. To talk about a water crisis hides intractable problems such as poverty.Consider the problems of water supply in Mexico City or Delhi. If you' re rich you drink mineral water and may even have a swimming-pool--yet millions in such cities can't get safe drinking water. People talk about the coming water crisis. I believe we have one now. It is a water crisis for the poor. 地球上的生命依赖于水,而且水是无法替代的. 目前人们的假设是,不管是饮用水还是农业、工业、渔业用水,我们对水的基本需要能够得到满足.在这一前提下,我们有两条基本道路可走：更合理地利用水资源或建立更多大型的水利工程.先来看看水利工程问题.我的大量研究的焦点在于如果你在河谷(尤其是非洲河谷)建立大坝,这会对湿地产生什么影响.该地区的生态几乎完全受控于河流的季节性变化——河水的涨落.事实上,如果你在上游建了水坝,通常会破坏下游的生态环境.过去,这类问题由于信息匮乏而鲜为人知.但在下个世纪,政府就不能为自己的盲目乐观找借口了. 工程师控制水流的能力产生了新的不可预知的结果.在非洲建水坝意味着渔业减产,草场减产,洪水泛滥区农业产量下降,所有这些都是事先未预料到的.而我们假定水坝的平均经济效益的寿命为30年,但水坝不会永远存在,我们还不知什么可以替代它.有关水的讨论的关键在于钱.谈论水危机掩饰了诸如贫穷这样棘手的问题.考虑一下墨西哥城或德里的水供应问题.如果你富有,你可以喝矿泉水,甚至于可以拥有一个游泳池——而这些城市数以百万计的居民却喝不上安全的饮用水.人们讨论着即将到来的水危机.我想我们现在已经有水危机了,这是一场穷人的水危机.