What are the environmental effects of water conservancy proj

What are the environmental effects of water conservancy projects?
水利工程对环境有什么影响?请用英语回答.

Well,I think there are both positive and negative effects of building water conservancy projects.
As we all know,building hydro projects such as a dam will help protecting city from being attacted by floods and it can be useful in the regulation and distribution of water so that we can guarantee people's need for water in daily life and production.In this sense,hydraulic engineering has beneficially environmental effects for human being.
However,at the same time,we should not ignore the adverse effects of hydro projects.Firstly,building water conservancy projects will cost a lot,it needs enough funds,advanced expertise and long time limits for projects.In other words,it will not only harass the people but also waste money.Secondly,the project may turn to disturb the balance of environment and ecosystem.For example,the Three Gorges Hydropower Station has proved to have effects on the climate of Province Sichuan and induces the serious earthquake in Wenchuan in 2008.
So I think we really need to be so cautious to building water conservancy projects considering of its two sides of environmental effects that we won't do the well-meaning but be misguided at last.
文章结构：
首段,陈述观点：建设水利工程有利有弊；
第二段：建设水利工程之利：防范水患,调节水源,保证生产生活用水.
第三段：建设水利工程之弊：劳民伤财+破坏生态平衡,举例：三峡导致四川地震
尾段：总结全文：我们应该对建设水利工程慎而又慎,以免好心办坏事.
再问： 你真厉害！你也是学水利的吗？能帮我再看看这个问题吗？：http://zhidao.baidu.com/question/394677179.html?quesup2&oldq=1 还有这个：http://zhidao.baidu.com/question/394676412.html?quesup2&oldq=1 太谢谢啦~~~！
再答： 亲，我……我不是学这个的，我是呃……个人观点。 啊，得到了专业人士的肯定啊，真开心！ 恩好，我去帮你看看。希望能帮你解决问题~ 刚刚看完你的两个问题。 我建议，如果你有自己的想法，只是不知道如何用英文说，你可以把中文发在补充问题里，我来给你翻译。 如果你觉得自己的想法还不成熟，那……那我帮你查查。 但是我也不是学这个专业的，可能会说错，不要嘲笑我哦！