Our grandparents' generation created an amazing system of canals and reservoirs that made it possible for people to live in places where there wasn't a lot of water. For example, during the Great Depression, they created the Hoover Dam, which in turn, created Lake Mead and made it possible for the cities of Las Vegas and Phoenix and Los Angeles to provide water for people who lived in a really dry place.
我们爷爷那一代人, 修建了伟大的运河和水库系统, 让人们可以在缺水的地方正常生活。 比如在大萧条时代, 他们修建了胡佛水坝, 拦下的水形成了米德湖, 为几个位于干旱地区的城市, 比如拉斯维加斯、凤凰城 和洛杉矶供水, 让那里的市民有水可用。
In the 20th century, we literally spent trillions of dollars building infrastructure to get water to our cities. In terms of economic development, it was a great investment. But in the last decade, we've seen the combined effects of climate change, population growth and competition for water resources threaten these vital lifelines and water resources.
在二十世纪,我们花费了数万亿美元, 为我们的城市修建供水系统。 对经济发展而言,这是笔不错的投资。 但在过去几十年间,我们看到 气候变化、人口增长 和水资源争夺带来的后果, 已经威胁到我们赖以生存的水资源。
This figure shows you the change in the lake level of Lake Mead that happened in the last 15 years. You can see starting around the year 2000, the lake level started to drop. And it was dropping at such a rate that it would have left the drinking water intakes for Las Vegas high and dry. The city became so concerned about this that they recently constructed a new drinking water intake structure that they referred to as the "Third Straw" to pull water out of the greater depths of the lake.
这张图表显示的是米德湖的水位 在过去15年的变化情况。 差不多从2000年开始, 水位开始下降。 下降的速度如此之快, 很快,为拉斯维加斯 供水的管道将抽不到水。 拉斯维加斯很担心这一点 他们最近铺设了一条新的抽水管道, 称之为“第三吸管”, 从湖的更深处抽水。
The challenges associated with providing water to a modern city are not restricted to the American Southwest. In the year 2007, the third largest city in Australia, Brisbane, came within 6 months of running out of water. A similar drama is playing out today in São Paulo, Brazil, where the main reservoir for the city has gone from being completely full in 2010, to being nearly empty today as the city approaches the 2016 Summer Olympics.
向现代都市供水的难题 不仅仅发生在美国西南部。 2007年,澳大利亚第三大城市,布里斯班, 整整6个月无水可用。 同样的情况也在巴西圣保罗上演, 圣市最主要的水库 在2010年还几乎全满, 如今已几乎见底, 而他们还将举办2016夏季奥运会。
For those of us who are fortunate enough to live in one of the world's great cities, we've never truly experienced the effects of a catastrophic drought. We like to complain about the navy showers we have to take. We like our neighbors to see our dirty cars and our brown lawns. But we've never really faced the prospect of turning on the tap and having nothing come out. And that's because when things have gotten bad in the past, it's always been possible to expand a reservoir or dig a few more groundwater wells. Well, in a time when all of the water resources are spoken for, it's not going to be possible to rely on this tried and true way of providing ourselves with water.
我们足够幸运, 能够生活在世界上最伟大的城市之一, 我们从未真正经历过大旱灾。 我们会抱怨洗澡的水不够大。 我们也经常不洗车,不浇草坪。 但我们从未经历过拧开水龙头, 却无水可用的状况。 因为在过去,如果发生这样的事情, 我们总是能把水库修得更大些, 或者多挖几口水井。 但如果所有的水资源都枯竭了, 那这种曾经屡试不爽的老办法 可能就不适用了。
Some people think that we're going to solve the urban water problem by taking water from our rural neighbors. But that's an approach that's fraught with political, legal and social dangers. And even if we succeed in grabbing the water from our rural neighbors, we're just transferring the problem to someone else and there's a good chance it will come back and bite us in the form of higher food prices and damage to the aquatic ecosystems that already rely upon that water.
有些人觉得,要解决城市用水问题, 从临近的农村取水就好了。 但这种方法充满了 政治、法律和社会风险。 即便我们能从农村取水, 那也不过是将问题转嫁到了别人头上, 而且很有可能,它会反噬到我们身上 要么会抬高食品价格, 要么会破坏水生生态系统。
I think that there's a better way to solve our urban water crisis and I think that's to open up four new local sources of water that I liken to faucets. If we can make smart investments in these new sources of water in the coming years, we can solve our urban water problem and decrease the likelihood that we'll ever run across the effects of a catastrophic drought.
我认为可以用更好的办法 来解决我们的城市用水危机, 就是下面我将要说的4种新水源, 我把它们比作4个水龙头。 在未来数年里,如果我们 能对这4种新水源 进行明智的投资, 我们就能解决城市用水问题, 使我们遭遇大旱灾的可能性 大大降低。
Now, if you told me 20 years ago that a modern city could exist without a supply of imported water, I probably would have dismissed you as an unrealistic and uninformed dreamer. But my own experiences working with some of the world's most water-starved cities in the last decades have shown me that we have the technologies and the management skills to actually transition away from imported water, and that's what I want to tell you about tonight.
如果在20年前,你告诉我, 现代城市可以在没有 外来水源的情况下得以发展, 我可能会觉得你是痴人说梦。 但在过去的几十年里, 我一直在世界上最缺水的城市工作, 这段经历告诉我,我们的技术和管理能力 已经可以不依赖于外来水源, 这就是今晚我想跟大家分享的。
The first source of local water supply that we need to develop to solve our urban water problem will flow with the rainwater that falls in our cities. One of the great tragedies of urban development is that as our cities grew, we started covering all the surfaces with concrete and asphalt. And when we did that, we had to build storm sewers to get the water that fell on the cities out before it could cause flooding, and that's a waste of a vital water resource. Let me give you an example.
要解决城市用水问题, 我们需要发展的第一种本地新水源 就是从天而降的雨水。 城市发展带来的最大灾难之一, 就是随着城市越变越大, 我们将所有地面都用 水泥和沥青覆盖起来了。 这样一来,我们必须修建巨大的排水管道, 将落在城市里的雨水排出去, 以免引发洪灾, 这对水资源是极大的浪费。 让我来举个例子。
This figure here shows you the volume of water that could be collected in the city of San Jose if they could harvest the stormwater that fell within the city limits. You can see from the intersection of the blue line and the black dotted line that if San Jose could just capture half of the water that fell within the city, they'd have enough water to get them through an entire year.
这张图表显示的是 圣何塞市能够收集到的雨水百分比, 与收集到的雨水总量间的关系。 注意看蓝线和黑虚线相交的地方, 如果圣何塞市能收集它降雨量的一半, 就足够全市用上一年。
Now, I know what some of you are probably thinking. "The answer to our problem is to start building great big tanks and attaching them to the downspouts of our roof gutters, rainwater harvesting." Now, that's an idea that might work in some places. But if you live in a place where it mainly rains in the winter time and most of the water demand is in the summertime, it's not a very cost-effective way to solve a water problem. And if you experience the effects of a multiyear drought, like California's currently experiencing, you just can't build a rainwater tank that's big enough to solve your problem.
我知道,有人可能会想, “那要解决用水问题, 只要做一些巨大的储水罐 跟屋顶排水沟的落水管连在一起, 收集雨水就行了。” 这方法在某些地方可能有用。 但如果你居住的城市冬天经常下雨, 而夏天用水量大, 这个方法就不是那么有效了。 而且,如果你所处的地方常年干旱, 就像今天的加利福尼亚州一样, 你做多大的储水罐也解决不了问题。
I think there's a lot more practical way to harvest the stormwater and the rainwater that falls in our cities, and that's to capture it and let it percolate into the ground. After all, many of our cities are sitting on top of a natural water storage system that can accommodate huge volumes of water.
我认为有更加现实的方法 来收集城市里的雨水, 那就是收集之后,让它渗入地下。 这样一来,我们城市的地底下 就有了一个天然的储水系统, 可以储存大量的水。
For example, historically, Los Angeles has obtained about a third of its water supply from a massive aquifer that underlies the San Fernando Valley. Now, when you look at the water that comes off of your roof and runs off of your lawn and flows down the gutter, you might say to yourself, "Do I really want to drink that stuff?" Well, the answer is you don't want to drink it until it's been treated a little bit. And so the challenge that we face in urban water harvesting is to capture the water, clean the water and get it underground.
比如说,在过去的洛杉矶, 它的用水量的三分之一都来自 圣费尔南多谷的地下蓄水层。 当你看到雨水从房顶滴落, 漫过草坪,流进沟渠, 你可能会犹豫,“我真的要喝这样的水吗?” 毫无疑问,要想喝这水, 得先经过处理。 因此,在城市里收集(雨)水有三大挑战, 收集雨水,清洁雨水, 灌入地下。
And that's exactly what the city of Los Angeles is doing with a new project that they're building in Burbank, California. This figure here shows the stormwater park that they're building by hooking a series of stormwater collection systems, or storm sewers, and routing that water into an abandoned gravel quarry. The water that's captured in the quarry is slowly passed through a man-made wetland, and then it goes into that ball field there and percolates into the ground, recharging the drinking water aquifer of the city.
洛杉矶已经开始这么做了, 他们在加利福尼亚州 伯班克市新建了一个项目。 这是一个雨水收集园区 他们将众多雨水收集系统 或者排水沟连接起来, 将雨水引入一个废弃的采石场。 采石场里的水 慢慢通过一个人造湿地 进入旁边的一个球型区域 然后渗入地下, 补充洛杉矶的地下蓄水层。
And in the process of passing through the wetland and percolating through the ground, the water encounters microbes that live on the surfaces of the plants and the surfaces of the soil, and that purifies the water. And if the water's still not clean enough to drink after it's been through this natural treatment process, the city can treat it again when they pump if back out of the groundwater aquifers before they deliver it to people to drink.
这些水在穿过湿地 渗入地下的过程中, 会接触到生活在植物和土壤表面 的微生物, 它们能净化水。 如果水在经过自然净化处理后, 还是不能直接饮用, 管理人员会把 从地下蓄水层抽出来的水 进行二次处理 然后再供市民饮用。
The second tap that we need to open up to solve our urban water problem will flow with the wastewater that comes out of our sewage treatment plants. Now, many of you are probably familiar with the concept of recycled water. You've probably seen signs like this that tell you that the shrubbery and the highway median and the local golf course is being watered with water that used to be in a sewage treatment plant. We've been doing this for a couple of decades now. But what we're learning from our experience is that this approach is much more expensive that we expected it to be. Because once we build the first few water recycling systems close to the sewage treatment plant, we have to build longer and longer pipe networks to get that water to where it needs to go. And that becomes prohibitive in terms of cost.
解决城市用水问题的第二个水龙头 是来自污水处理厂 处理过的废水。 大家对于循环水应该已经不陌生了。 你们也许都见过这样的牌子 上面写着灌木丛、高速公路隔离绿化带 本地高尔夫球场 的灌溉用水 都来自污水处理系统。 几十年来我们都是这么做的。 但几十年的经验告诉我们, 这样做的成本比我们预期的要高。 因为一旦我们在污水处理厂附近 建起水循环系统, 我们就不得不建造越来越长的管网 把水送到需要的地方去。 这笔开销真心不小。
What we're finding is that a much more cost-effective and practical way of recycling wastewater is to turn treated wastewater into drinking water through a two-step process. In the first step in this process we pressurize the water and pass it through a reverse osmosis membrane: a thin, permeable plastic membrane that allows water molecules to pass through but traps and retains the salts, the viruses and the organic chemicals that might be present in the wastewater.
我们发现, 更加经济实惠和可行的办法 是将处理过的废水变成饮用水, 只需要两步。 第一步是给水加压, 让它通过反向渗透膜 ——一种很薄的、可渗透的塑料膜—— 水分子可以通过, 但废水中可能含有的盐、病毒和有机化学物 会被拦截下来。
In the second step in the process, we add a small amount of hydrogen peroxide and shine ultraviolet light on the water. The ultraviolet light cleaves the hydrogen peroxide into two parts that are called hydroxyl radicals, and these hydroxyl radicals are very potent forms of oxygen that break down most organic chemicals.
第二步, 我们往水里加入少量的过氧化氢 然后用紫外线进行照射。 紫外线能将过氧化氢 分裂成两部分,称为氢氧基, 氢氧基是一种非常强的氧气形式 能够消灭大部分有机化学物。
After the water's been through this two-stage process, it's safe to drink. I know, I've been studying recycled water using every measurement technique known to modern science for the past 15 years. We've detected some chemicals that can make it through the first step in the process, but by the time we get to the second step, the advanced oxidation process, we rarely see any chemicals present. And that's in stark contrast to the taken-for-granted water supplies that we regularly drink all the time.
水经过这两步处理之后, 就可以安全饮用了。 过去15年里, 我一直在运用 现代科学的各种测量方法 来研究循环水。 我们发现某些化学物质 无法在步骤一被过滤掉, 但经过第二步: 高级氧化过程之后, 几乎没有化学物质能残留下来。 这比我们一直喝的“毫无问题”的水 可安全多了。
There's another way we can recycle water. This is an engineered treatment wetland that we recently built on the Santa Ana River in Southern California. The treatment wetland receives water from a part of the Santa Ana River that in the summertime consists almost entirely of wastewater effluent from cities like Riverside and San Bernardino. The water comes into our treatment wetland, it's exposed to sunlight and algae and those break down the organic chemicals, remove the nutrients and inactivate the waterborne pathogens. The water gets put back in the Santa Ana River, it flows down to Anaheim, gets taken out at Anaheim and percolated into the ground, and becomes the drinking water of the city of Anaheim, completing the trip from the sewers of Riverside County to the drinking water supply of Orange County.
还有另外一种方法来循环水。 这是我们最近修建的人工湿地 位于加利福尼亚州南部的圣安娜河上。 圣安娜河的部分河水流入人工湿地, 每到夏天,圣安娜河里就全是污水, 都来自里弗赛德市和圣贝纳迪诺市。 河水流入我们的人工湿地, 在阳光暴晒和水藻的作用下, 有机化学物被分解, 营养物被消耗,水生病原体被杀死。 之后河水流回圣安娜河, 流向安纳海姆市, 河水在那里被抽出, 渗入地下, 成为安纳海姆市的饮用水, 通过这一过程,里弗赛德郡的废水 就变成了橙郡的饮用水。
Now, you might think that this idea of drinking wastewater is some sort of futuristic fantasy or not commonly done. Well, in California, we already recycle about 40 billion gallons a year of wastewater through the two-stage advanced treatment process I was telling you about. That's enough water to be the supply of about a million people if it were their sole water supply.
也许你们会觉得,将废水变成饮用水, 只是天方夜谭,或者还没有得到推广。 实际上,运用我刚刚介绍的两步处理法, 我们每年在加利福尼亚州循环利用的水 达到了1.5亿立方米。 这些水足够供应100万人, 作为他们的主要水源。
The third tap that we need to open up will not be a tap at all, it will be a kind of virtual tap, it will be the water conservation that we manage to do. And the place where we need to think about water conservation is outdoors because in California and other modern American cities, about half of our water use happens outdoors.
我们的第三个水龙头并不是实体, 而是虚拟的, 指的是节约用水。 而且主要指的是户外用水, 因为在加利福尼亚以及其他的美国都市, 差不多一半的用水发生在户外。
In the current drought, we've seen that it's possible to have our lawns survive and our plants survive with about half as much water. So there's no need to start painting concrete green and putting in Astroturf and buying cactuses. We can have California-friendly landscaping with soil moisture detectors and smart irrigation controllers and have beautiful green landscapes in our cities.
即使在现在的干旱状态下, 我们的用水量下降了一半, 但我们的草坪,我们的植物 还是活下来了。 因此我们还没到把水泥地喷成绿色, 或者改铺人工草皮,改种仙人掌的地步。 在土壤湿度探测器和智能浇灌系统的帮助下, 加州式园林不是梦, 我们的城市依旧可以绿意盎然。
The fourth and final water tap that we need to open up to solve our urban water problem will flow with desalinated seawater. Now, I know what you probably heard people say about seawater desalination. "It's a great thing to do if you have lots of oil, not a lot of water and you don't care about climate change." Seawater desalination is energy-intensive no matter how you slice it. But that characterization of seawater desalination as being a nonstarter is hopelessly out of date. We've made tremendous progress in seawater desalination in the past two decades.
我们需要打开的第四个, 也是最后一个水龙头, 来解决城市用水问题, 是海水淡化。 也许你们听人们谈论过海水淡化, “海水淡化是很好, 前提是你石油多、淡水少, 而且也不在乎气候变化。” 没错,海水淡化 是一项能源密集型产业。 但如果仅仅因为这样,就将海水淡化 视为没有前途,那就太落伍了。 在过去20年间,我们在海水淡化上 已经取得了巨大进展。
This picture shows you the largest seawater desalination plant in the Western hemisphere that's currently being built north of San Diego. Compared to the seawater desalination plant that was built in Santa Barbara 25 years ago, this treatment plant will use about half the energy to produce a gallon of water.
这张照片上 是在建的西半球最大的海水淡化厂, 位于圣地亚哥市以北。 与25年前建在圣巴巴拉市 的海水淡化厂相比, 这家海水淡化厂每生产一加仑淡水 的能耗下降了一半。
But just because seawater desalination has become less energy-intensive, doesn't mean we should start building desalination plants everywhere. Among the different choices we have, it's probably the most energy-intensive and potentially environmentally damaging of the options to create a local water supply.
当然,海水淡化的能耗降低了, 并不意味着我们就该到处建海水淡化厂。 在我们的众多选择中, 在4种新水源中, 海水淡化依然是能耗最大, 最有可能对环境造成危害的。
So there it is. With these four sources of water, we can move away from our reliance on imported water. Through reform in the way we landscape our surfaces and our properties, we can reduce outdoor water use by about 50 percent, thereby increasing the water supply by 25 percent. We can recycle the water that makes it into the sewer, thereby increasing our water supply by 40 percent. And we can make up the difference through a combination of stormwater harvesting and seawater desalination.
综上所述, 有了这4种新水源, 我们不用再依赖进口水。 通过改进我们绿化城市和居民区的方法, 我们可以将户外用水量下降50%, 因此提高25%的供水量。 我们可以循环利用废水, 以此提高40%供水量。 我们可以综合利用 雨水收集和海水淡化。
So, let's create a water supply that will be able to withstand any of the challenges that climate change throws at us in the coming years. Let's create a water supply that uses local sources and leaves more water in the environment for fish and for food. Let's create a water system that's consistent with out environmental values. And let's do it for our children and our grandchildren and let's tell them this is the system that they have to take care of in the future because it's our last chance to create a new kind of water system.
让我们来创造稳定的水源供应, 足以在未来几年承受气候变化 给我们带来的挑战。 让我们充分利用本地水源, 将更多的水留给环境, 留给动物,留给食物。 让我们创造环境友好型的供水系统。 让我们为子孙后代而努力, 告诉他们,在未来的岁月里, 他们也应该珍视这个系统 因为这是我们创建 新型供水系统最后的机会。
Thank you very much for your attention.
非常感谢大家。
(Applause)
(掌声)