4 ways we can avoid a catastrophic drought | David Sedlak

譯者: Regina Chu 審譯者: Marssi Draw

Our grandparents' generation created an amazing system

我們的祖父輩創造了一套

非常棒的渠道及水庫系統，

of canals and reservoirs that made it possible

讓大家能住在水不多的地方。

for people to live in places where there wasn't a lot of water.

For example, during the Great Depression,

譬如在美國大蕭條時期，

they created the Hoover Dam,

他們建造出胡佛水壩，

which in turn, created Lake Mead

也因而造出人工湖米德湖，

and made it possible for the cities of Las Vegas and Phoenix

能為拉斯維加斯、鳳凰城

and Los Angeles to provide water

及洛杉磯供水，

for people who lived in a really dry place.

讓大家能住在很乾燥的地方。

In the 20th century, we literally spent trillions of dollars

20 世紀時， 我們確實花了幾兆美元

building infrastructure to get water to our cities.

做基礎建設送水到城市。

In terms of economic development, it was a great investment.

以經濟發展而言， 這是一項偉大的投資。

But in the last decade, we've seen the combined effects

但是在過去十年， 我們看到氣候變遷

of climate change, population growth and competition for water resources

與人口成長的綜合影響， 而對水資源的競爭

threaten these vital lifelines and water resources.

威脅到這些重要的 命脈及水資源。

This figure shows you the change in the lake level of Lake Mead

這張表顯示米德湖水位

that happened in the last 15 years.

在過去十五年的變化。

You can see starting around the year 2000,

大家可以看到 大約從 2000 年開始，

the lake level started to drop.

水位開始下降。

And it was dropping at such a rate

下降幅度之快，

that it would have left the drinking water intakes for Las Vegas high and dry.

讓拉斯維加斯飲用水取水口 遠高過湖水位並乾涸。

The city became so concerned about this

該市非常擔心，

that they recently constructed a new drinking water intake structure

因此他們最近新建了 一個飲用水取水口，

that they referred to as the "Third Straw"

他們稱之為「第三根吸管」，

to pull water out of the greater depths of the lake.

從愈來愈低的湖中取水。

The challenges associated with providing water to a modern city

供水給現代都市所面臨的挑戰

are not restricted to the American Southwest.

並非只限於美南地區。

In the year 2007, the third largest city in Australia, Brisbane,

2007 年，澳洲 第三大都市布里斯本

came within 6 months of running out of water.

缺水缺了六個月。

A similar drama is playing out today in São Paulo, Brazil,

今天類似的情景 也在巴西聖保羅上演，

where the main reservoir for the city

該市的主要水庫

has gone from being completely full in 2010,

從 2010 年滿水位狀況，

to being nearly empty today

到今天幾乎完全乾涸，

as the city approaches the 2016 Summer Olympics.

而該市正準備舉行 2016 年夏季奧運會。

For those of us who are fortunate enough

對我們這些有幸住在世界

to live in one of the world's great cities,

各個重大都市的人而言，

we've never truly experienced the effects of a catastrophic drought.

我們從未真正體驗過 毀滅性的旱災。

We like to complain about the navy showers we have to take.

我們抱怨要洗戰鬥澡。

We like our neighbors to see our dirty cars and our brown lawns.

我們喜歡讓鄰居看見 我們的髒車及枯黃的草皮。

But we've never really faced the prospect of turning on the tap

但是我們從未真正面對過

打開水龍頭 卻無水可用的窘境。

and having nothing come out.

And that's because when things have gotten bad in the past,

這是因為過去情況變糟時，

it's always been possible to expand a reservoir

我們總是有辦法擴建水庫，

or dig a few more groundwater wells.

或挖更多口地下水井。

Well, in a time when all of the water resources are spoken for,

在所有水資源 都已開發殆盡的年代，

it's not going to be possible to rely on this tried and true way

我們不可能再依賴這種 已知可行的方法

of providing ourselves with water.

來提供用水。

Some people think that we're going to solve the urban water problem

有些人認為我們可以 向都市四周有水源的地主借水

by taking water from our rural neighbors.

以解決都市的供水問題。

But that's an approach that's fraught with political, legal and social dangers.

但是這個方法伴隨著 政治、法律及社會威脅。

And even if we succeed in grabbing the water from our rural neighbors,

即使我們能從四周鄰居 成功搶到水，

we're just transferring the problem to someone else

我們只是把問題轉移給別人，

and there's a good chance it will come back and bite us

這個問題很有可能

會以高漲的食物價格 回頭反咬我們一口，

in the form of higher food prices

and damage to the aquatic ecosystems that already rely upon that water.

並破壞靠此水為生的 水生生態系。

I think that there's a better way to solve our urban water crisis

我認為有更好的方法 解決都市的水危機，

and I think that's to open up four new local sources of water

而方法就是開拓四種 新的當地水資源，

that I liken to faucets.

我比作打開水龍頭。

If we can make smart investments in these new sources of water

如果我們可以明智地 投資在這些新的水資源上，

in the coming years,

在未來幾年，

we can solve our urban water problem

我們就能解決都市水問題，

and decrease the likelihood that we'll ever run across

並減低我們碰到

the effects of a catastrophic drought.

毀滅性旱災後果的可能性。

Now, if you told me 20 years ago

如果你在 20 年前跟我說

that a modern city could exist without a supply of imported water,

一個現代化都市 不用從外面引水也可以生存，

I probably would have dismissed you as an unrealistic and uninformed dreamer.

我大概會把你打發走， 說你是不切實際又無知的空想家。

But my own experiences

但是依我自己的經驗，

working with some of the world's most water-starved cities in the last decades

在過去幾十年與世界上 幾個非常缺水的都市合作後，

have shown me that we have the technologies and the management skills

讓我知道我們的確有 科技與管理技巧

to actually transition away from imported water,

能真的轉變到不用從外面引水，

and that's what I want to tell you about tonight.

這也是我今晚的主題。

The first source of local water supply that we need to develop

我們第一個要打開的 當地供水資源

to solve our urban water problem

以解決我們的都市水問題，

will flow with the rainwater that falls in our cities.

會流出降在都市內的雨水。

One of the great tragedies of urban development

都市發展的大悲劇之一，

is that as our cities grew,

就是隨著都市成長，

we started covering all the surfaces with concrete and asphalt.

我們以混凝土及瀝青 覆蓋所有的表面。

And when we did that, we had to build storm sewers

在我們如此做的同時， 又必須蓋雨水下水道

to get the water that fell on the cities out

將降下的雨水排到都市外，

before it could cause flooding,

不然會引起水災，

and that's a waste of a vital water resource.

這浪費了我們重要的水資源。

Let me give you an example.

舉一個例子，

This figure here shows you the volume of water

這張表顯示

that could be collected in the city of San Jose

在矽谷聖荷西市 能收集的雨水水量，

if they could harvest the stormwater that fell within the city limits.

只要他們能把市區範圍內的 雨水全都收集起來。

You can see from the intersection of the blue line and the black dotted line

從藍線與黑點線的交點可以看到

that if San Jose could just capture half of the water that fell within the city,

聖荷西只要能收集 降在市區範圍內一半的雨水，

they'd have enough water to get them through an entire year.

就有足夠的水撐過一整年。

Now, I know what some of you are probably thinking.

我知道有些人可能會這麼想：

"The answer to our problem is to start building great big tanks

「那我們的解決方案就是 開始裝幾個大桶子，

and attaching them to the downspouts of our roof gutters,

與簷槽的雨落水管相連，

rainwater harvesting."

收集雨水。」

Now, that's an idea that might work in some places.

這個想法在某些地方或許可行。

But if you live in a place where it mainly rains in the winter time

但是如果你住的地方 雨季主要在冬天，

and most of the water demand is in the summertime,

最需要水的時候卻是夏天，

it's not a very cost-effective way to solve a water problem.

這就不是非常 具經濟效益的解決方法。

And if you experience the effects of a multiyear drought,

如果你經歷多年旱災的影響，

like California's currently experiencing,

像加州現在一樣，

you just can't build a rainwater tank that's big enough to solve your problem.

你不可能蓋一個夠大的 雨水儲槽來解決問題。

I think there's a lot more practical way

我想有很多更實際的方式

to harvest the stormwater and the rainwater that falls in our cities,

能收集降在市區範圍內的雨水，

and that's to capture it and let it percolate into the ground.

那就是要留住雨水 並滲透到地下。

After all, many of our cities are sitting on top of a natural water storage system

畢竟，許多城市 都位於天然儲水系統上方，

that can accommodate huge volumes of water.

能容納大量的水。

For example, historically, Los Angeles has obtained

舉例而言， 歷史上洛杉磯曾經

about a third of its water supply from a massive aquifer

從聖費爾南多谷下方的蓄水層 取得約三分之一的供水。

that underlies the San Fernando Valley.

Now, when you look at the water that comes off of your roof

現在，當你看著屋頂上的水

and runs off of your lawn and flows down the gutter,

流過你的草坪，從屋簷流下，

you might say to yourself, "Do I really want to drink that stuff?"

你大概會對自己說： 「那種水真的能喝嗎？」

Well, the answer is you don't want to drink it

答案是你不想喝那種水，

until it's been treated a little bit.

除非這水經過一些處理。

And so the challenge that we face in urban water harvesting

所以我們收集都市雨水 要面對的挑戰，

is to capture the water, clean the water

就是要把水留住、弄乾淨

and get it underground.

並存入地下。

And that's exactly what the city of Los Angeles is doing

這正是洛杉磯市目前正在執行的，

with a new project that they're building in Burbank, California.

他們在柏本克市興建一項新計畫。

This figure here shows the stormwater park that they're building

這張圖是他們正在興建的 雨水處理廠，

by hooking a series of stormwater collection systems, or storm sewers,

他們將一系列的雨水收集系統 即雨水下水道連接起來，

and routing that water into an abandoned gravel quarry.

將收集的水導入一座 廢棄的採石場。

The water that's captured in the quarry

在此採石場收集到的水，

is slowly passed through a man-made wetland,

會慢慢流經一座人造溼地，

and then it goes into that ball field there

然後進入那塊沙洲，

and percolates into the ground,

再滲入地面，

recharging the drinking water aquifer of the city.

補注該市的飲用水蓄水層。

And in the process of passing through the wetland

在通過溼地

and percolating through the ground,

及滲入地下的過程中，

the water encounters microbes that live on the surfaces of the plants

水會碰到存在於植物表面

and the surfaces of the soil,

及土表的微生物，

and that purifies the water.

這會淨化水。

And if the water's still not clean enough to drink

如果這些水仍然 不夠乾淨到能喝的程度，

after it's been through this natural treatment process,

在這項天然的處理過程之後，

the city can treat it again

該市會再處理一次，

when they pump if back out of the groundwater aquifers

他們從地下水層抽水出來，

before they deliver it to people to drink.

處裡後再供水給大家喝。

The second tap that we need to open up to solve our urban water problem

我們要解決都市水問題 該開的第二個水龍頭

will flow with the wastewater

會流出廢水，

that comes out of our sewage treatment plants.

從我們的汙水處理廠出來。

Now, many of you are probably familiar with the concept of recycled water.

在座很多人大概還滿熟悉 再生水（中水）的概念。

You've probably seen signs like this

你大概看過像這樣的標誌，

that tell you that the shrubbery and the highway median

顯示這塊灌木叢、 高速公路的中央安全島、

and the local golf course

還有家附近的高爾夫球場

is being watered with water

都用再生水灌溉，

that used to be in a sewage treatment plant.

從汙水處理廠裡流出來。

We've been doing this for a couple of decades now.

這早已行之有年。

But what we're learning from our experience

但是我們從經驗得知

is that this approach is much more expensive that we expected it to be.

這個方式遠比我們預期的貴很多。

Because once we build the first few water recycling systems

因為一旦我們蓋了 頭幾座再生水系統廠，

close to the sewage treatment plant,

位於汙水處理廠附近，

we have to build longer and longer pipe networks

我們就必須接愈來愈長的管線

to get that water to where it needs to go.

把水輸送到該去的地方。

And that becomes prohibitive in terms of cost.

這會讓人卻步，因為成本過高。

What we're finding is

我們發現

that a much more cost-effective and practical way of recycling wastewater

更具經濟效益 及更實際的再生廢水方法，

is to turn treated wastewater into drinking water

是把處理過的廢水變成飲水，

through a two-step process.

這要透過二個處理步驟。

In the first step in this process we pressurize the water

第一步是將水加壓

and pass it through a reverse osmosis membrane:

讓它通過逆滲透膜：

a thin, permeable plastic membrane

那是一層可滲透的塑膠薄膜，

that allows water molecules to pass through

讓水分子通過，

but traps and retains the salts, the viruses and the organic chemicals

但是會抓住及留住鹽分、 病毒及有機化學物質，

that might be present in the wastewater.

這些東西可能存在於廢水中。

In the second step in the process,

處理過程的第二步

we add a small amount of hydrogen peroxide

是注入少量的過氧化氫

and shine ultraviolet light on the water.

及照射紫外線。

The ultraviolet light cleaves the hydrogen peroxide

紫外線會分解過氧化氫

into two parts that are called hydroxyl radicals,

成為兩個氫氧自由基，

and these hydroxyl radicals are very potent forms of oxygen

氫氧自由基 是非常有力的氧形式，

that break down most organic chemicals.

會分解大部分的有機化學物質。

After the water's been through this two-stage process,

水經過這兩個步驟處理後，

it's safe to drink.

可以安全飲用。

I know,

我知道，

I've been studying recycled water

我利用所有現代科學 已知的測量技術

using every measurement technique known to modern science

研究再生水

for the past 15 years.

研究了 15 年。

We've detected some chemicals

我們偵測到某些化學物品

that can make it through the first step in the process,

可以通過此處理過程的第一步，

but by the time we get to the second step,

但是到了第二步，

the advanced oxidation process,

即高級氧化程序，

we rarely see any chemicals present.

我們很難再看到任何化學物品。

And that's in stark contrast to the taken-for-granted water supplies

這與我們天天飲用、 視為理所當然的自來水

that we regularly drink all the time.

形成鮮明對比。

There's another way we can recycle water.

還有一種方法可以再生水。

This is an engineered treatment wetland that we recently built

這是我們剛興建的人工溼地，

on the Santa Ana River in Southern California.

位於南加州聖塔安娜河。

The treatment wetland receives water from a part of the Santa Ana River

這座人工溼地接收 從聖塔安娜河部分河段進來的水，

that in the summertime consists almost entirely of wastewater effluent

夏天時幾乎全是廢汙水，

from cities like Riverside and San Bernardino.

由河濱市及聖伯那地諾市等地排放。

The water comes into our treatment wetland,

廢汙水進入我們的處理溼地，

it's exposed to sunlight and algae

曝露於陽光及藻類下，

and those break down the organic chemicals,

這個過程會分解有機化學物，

remove the nutrients and inactivate the waterborne pathogens.

去除營養物 並使水媒病原體失去活性。

The water gets put back in the Santa Ana River,

該水再流放回聖塔安納河，

it flows down to Anaheim,

往下流到安納罕，

gets taken out at Anaheim and percolated into the ground,

然後在安納罕滲透入地面，

and becomes the drinking water of the city of Anaheim,

並成為安納罕市的飲水，

completing the trip from the sewers of Riverside County

是一趟從河濱縣的廢汙水

to the drinking water supply of Orange County.

轉變成橘縣飲用水的完美旅程。

Now, you might think that this idea of drinking wastewater

你可能會認為 這種喝廢水的想法

is some sort of futuristic fantasy or not commonly done.

是某種未來的幻想 或不常見。

Well, in California, we already recycle about 40 billion gallons a year

但是在加州，我們每年 已再生一千五百多億公升廢水，

of wastewater through the two-stage advanced treatment process

都由這種我剛剛提到的 二階段式的高級氧化處理過程再生，

I was telling you about.

That's enough water to be the supply of about a million people

這個量足夠提供 大約一百萬人使用，

if it were their sole water supply.

如果這是他們唯一的水源。

The third tap that we need to open up will not be a tap at all,

我們必須打開的第三個水龍頭 跟水龍頭一點關係都沒有，

it will be a kind of virtual tap,

它是虛擬的水龍頭，

it will be the water conservation that we manage to do.

它就是我們能做到的節約用水。

And the place where we need to think about water conservation is outdoors

我們要思索 如何節約的地方是戶外，

because in California and other modern American cities,

因為在加州 及美國其它現代都市，

about half of our water use happens outdoors.

我們的水有一半用在戶外。

In the current drought,

目前的乾旱

we've seen that it's possible

讓我們看見

to have our lawns survive and our plants survive

要讓草皮及植物生存，

with about half as much water.

只要以往一半的水就夠了，

So there's no need to start painting concrete green

所以實在不需要 把門前車道噴成綠色、

and putting in Astroturf and buying cactuses.

鋪上人工草皮及買仙人掌。

We can have California-friendly landscaping with soil moisture detectors

我們可以用適合加州的園藝造景， 裝上土壤水分偵測器

and smart irrigation controllers

及智慧型澆水控制器，

and have beautiful green landscapes in our cities.

就能在城市裡有美麗的綠色園景。

The fourth and final water tap that we need to open up

我們要開的第四個 也是最後一個水龍頭

to solve our urban water problem

以解決都市水問題，

will flow with desalinated seawater.

會流出海水淡化水。

Now, I know what you probably heard people say about seawater desalination.

我知道你們大概聽過 別人這樣說海水淡化：

"It's a great thing to do if you have lots of oil, not a lot of water

「如果你有大量石油， 卻沒有大量的水，

and you don't care about climate change."

而且你也不在乎氣候變遷， 那這是件好事。」

Seawater desalination is energy-intensive no matter how you slice it.

無論你怎麼看， 海水淡化都非常耗能。

But that characterization of seawater desalination

但是把海水淡化視為

as being a nonstarter is hopelessly out of date.

毫無前途 是無可救藥的過時想法。

We've made tremendous progress in seawater desalination

海水淡化在過去二十年 已有長足進步。

in the past two decades.

This picture shows you

這張照片上面

the largest seawater desalination plant in the Western hemisphere

是西半球最大的海水淡化廠，

that's currently being built north of San Diego.

目前正在聖地牙哥北邊興建。

Compared to the seawater desalination plant

與另一座海水淡化廠相比，

that was built in Santa Barbara 25 years ago,

25 年前建於聖塔芭芭拉，

this treatment plant will use about half the energy

這座處理廠生產一加侖的水

to produce a gallon of water.

只要用約一半的能量。

But just because seawater desalination has become less energy-intensive,

但是就算海水淡化 現在比較不那麼耗能，

doesn't mean we should start building desalination plants everywhere.

也不代表我們就該在四處 開始興建處理廠。

Among the different choices we have,

在我們各種選項中，

it's probably the most energy-intensive

這大概是最耗能源、

and potentially environmentally damaging

最破壞環境的一種方法

of the options to create a local water supply.

來創造當地水資源。

So there it is.

情況就是這樣。

With these four sources of water,

開了這四個水龍頭，

we can move away from our reliance on imported water.

我們就不需仰賴外地引水。

Through reform in the way we landscape our surfaces and our properties,

透過改良我們園藝造景的方法，

we can reduce outdoor water use by about 50 percent,

我們可以節省 約 50% 的戶外用水，

thereby increasing the water supply by 25 percent.

因而增加 25% 的供水。

We can recycle the water that makes it into the sewer,

我們可以再生廢汙水，

thereby increasing our water supply by 40 percent.

因而增加 40% 供水。

And we can make up the difference through a combination

我們也可以透過結合

of stormwater harvesting and seawater desalination.

收集雨水及海水淡化補足供水量。

So, let's create a water supply

所以，讓我們創造一套

that will be able to withstand any of the challenges

能夠承受任何挑戰的供水法，

that climate change throws at us in the coming years.

在未來幾年能因應 氣候變遷帶來的挑戰。

Let's create a water supply that uses local sources

讓我們創造一套使用當地水資源

and leaves more water in the environment for fish and for food.

並能在環境中留更多水 給魚類、給糧食用的方法。

Let's create a water system that's consistent with out environmental values.

讓我們創造一套能與 環境價值相符合的供水系統。

And let's do it for our children and our grandchildren

讓我們為子孫做這件事，

and let's tell them this is the system

並告訴他們

未來他們要好好照顧這套系統，

that they have to take care of in the future

because it's our last chance to create a new kind of water system.

因為這是我們創造 新式供水系統的最後機會。

Thank you very much for your attention.

謝謝大家專心聆聽。

(Applause)

（掌聲）