Listen to part of a talk in an Environmental Science class.
请听一段环境科学课上的演讲。
So, I wanted to discuss a few other terms here...actually, some, uh some ideas about how we manage our resources.
我想谈谈一些其他的术语，一些关于我们如何管理我们的资源的想法。
Let's talk about what that...what that means.
我们来说说那是什么意思。
If we take a resource like water...well, maybe we should get a little bit more specific here—
如果我们拿水这个资源来举例子，可能会更具体一点——
back up from the more general case—and talk about underground water in particular.
用更普通的情况来支持这个观点——特别讲一讲地下水。
So, hydrogeologists have tried to figure out...how much water can you take out from underground sources?
水文地质学家试过搞清楚，我们能从地下资源中取出多少水？
This has been an important question. Let me ask you guys:
那是个重要的问题。我来问问你们：
how much water, based on what you know so far, could you take out of, say, an aquifer...under the city?
基于你们目前的知识，你们觉得从城市下面的一个含水层能取到多少水？
As...as much as would get recharged?
和能得到补充的量一样？
OK. So, we wouldn't want to take out any more than naturally comes into it.
那么我们不会想取出比自然进入含水层的水更多的水。
The implication is that, uh, well, if you only take as much out as comes in,
意义就是，如果你只取出流进去的量，
you're not gonna deplete the amount of water that's stored in there, right? Wrong, but that's the principle.
就不会耗尽储存在那里的水量，对吗？错，但那是原则。
That's the idea behind how we manage our water supplies. It's called “safe yield.”
那是我们管理水资源背后的原则。称为“安全产水量”。
Basically what this method says is that you can pump as much water out of a system as naturally recharges...as naturally flows back in.
基本上那个方式表示的就是人们可以从一个体系中抽取和自然补充量，自然流回系统的水量同样多的水。
So, this principle of safe yield—it's based on balancing what we take out with what gets recharged.
所以，这个安全产水量的原则，它基于对我们取出和得到补给的水量的平衡。
But what it does is, it ignores how much water naturally comes out of the system.
但它忽略了有多少水自然地流出体系。
In a natural system, a certain amount of recharge comes in and a certain amount of water naturally flows out through springs, streams, and lakes.
在一个自然的水体系中，会有一定量的补给水流进来，也会有一定量的水自然地流出进入泉水、溪流和湖泊。
And over the long term the amount that's stored in the aquifer doesn't really change much. It's balanced.
长期来看，储存在该含水层中的水量不会变化很大。处于平衡状态。
Now humans come in...and start taking water out of the system. How have we changed the equation?
而人类进入了，开始从这个体系中取水。我们如何改变了这个平衡？