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水4.0:饮用水的过去、现在与未来 (双语Ch 7节选)

已有 1814 次阅读 2015-9-8 15:28 |个人分类:Water 4.0|系统分类:科普集锦|关键词:Water,4.0,,Chapter,7| Water, chapter



“Drains to Bay”



On the curb across the street from my office there is a sign with apicture of a little blue fish ringed by the words, “No Dumping—Drains to Bay.” Underneath the sign sits the storm sewer—an entry point for rainwater traveling through the underground pipe system designed to protect the sity of Berkeley, California, from flooding. Any water flowing into the storm sewer makes a speedy trip under the city to a pipe that ends at the edge of San Francisco Bay. Along with the rainwater, anything else that has found its way into thestreet, like trash, leaves, or dirt, gets dumped into the bay and beyond.



The storm sewers in your neighborhood, which may or may not have acute sign stenciled above them, might follow the same practice, draining rain and melted snow to a local stream, river, lake, or bay. Then again, they might be connected to the same underground pipe system that carries wastes from your home to the sewage treatment plant. Either way, these long-ignored systems are falling apart. And as they deteriorate, they will endanger our health as wellas the habitats of fish, insects, and birds living in and around our inland and coastal waters.


Like the underground pipe networks developed to remove wastes from homes and streets during the nineteenth century, the urban drainage systems built over the past three centuries were an expedient means of moving unwanted water out of cities. But in the process of solving one problem, we created a new one: although the sewers quickly transported large volumes of water away from flood-prone streets, they often damaged the places where the water was discharged. In light of the difficulties faced by cities currently struggling to repair decaying pipes and to keep up with the increasing volume of water their existing drainage systems, it evident that in the near future we aregoing to have to spend hundreds of billions of dollars on these concrete and cast-ion plumbing systems.1


The need for huge investments in urban drainage also represents an opportunity: by building new types of drainage systems that take advantage ofthe ability of natural systems to store and purify water, we might be able toend up in a better place. With a little ingenuity, we can reinvent storm sewers in a manner that saves money, improves the environment, and even replenish our drinking water supply.


Why does a city need a drainage system, anyway? Consider what happens when rain lands in a park, a plot of forest, or a farmer’s field. Much of thewater percolates into the soil, where it provides moisture to plants andrecharge groundwater. The water that does not soak into the soil flows gently downhill under the force of gravity. Along the way, it forms rivulets, which join together to form a network of streams and rivers.


Now consider the consequences of covering the land with buildings and other impervious surfaces that prevent water from soaking into the soil. If the hard surfaces were perfectly flat, the accumulated water would form gigantic puddles. But this rarely happens because most land is sloped, even after it iscovered with asphalt or concrete. As a result, all the rainwater still flows downhill. If this large amount of water were to stay in a city, it would turn streets into rivers every time it rained and, much to the chagrin of homeownersand insurance agents, flood the basements of homes in low-lying areas. This process is exactly what happens in slums of developing countries that have been built without storm sewers.

在,想象一下当土地被建筑物及其他不透水的表面所覆盖,从而阻止水分渗入土壤的果 。倘若硬的地表足平坦,累的水将会形成一个巨大的水洼。当然,因即使土地上了青或混凝土后,大部分的地面斜的。于是,所有的雨水依然往低流。如果大量的水存在城市里的,每次下雨街道都会成江河,地势较低的地下室会被淹没,房主和保机构来很多烦恼种情况在展中国家的民窟尤,因没有雨水下水道。


(Last two paragraphs of Chapter 7)

The public is usually oblivious to urban drainage problems. Consequently, if low-impact development is going to succeedat the scale of an entire city, committed advocates are needed from outside ofthe water sector. One of the best examples of the level of commitment needed to successfully launch a citywide low-impact development project is Philadelphia’s “Green City, Clean Waters” program. Faced with the prospect of an expensive retrofit to address its combined sewer overflow problem, Philadelphia’s mayor, Michael Nutter, decided shortly after his inauguration in 2008 to pursue low-impact development as an alternative to the conventional engineering approach.46 But simply choosing low-impact development over underground tunnels was not enough. In addition to pushing for cooperation from the city’s water department, which had led previous efforts to combat the city’s combined sewer overflows, the mayor enlisted support from the government departments responsible for Philadelphia’s parks, schools, transportation, and taxcollection. After he got the buy-in from city agencies, he turned to sellinghis program to the public. To do this, he established a comprehensive program called “Greenworks Philadelphia” that explained his vision for the ways in which green infrastructure would transform every aspect of city life. Inessence, he made a commitment to supporting green development as mayor.


The consent decree that the mayor signed in 2012 with the Environmental Protection Agency commits the city to a twenty-five-year program that will cover about one third of the city’s impervious surfaces with green roofs, raingardens, permeable pavement, and other low-impact development features capable of capturing and retaining the first 2.9 cm (one inch) of precipitation.47 If everything goes according to plan, Philadelphia will invest approximately $2.5 billion in projects on city-owned land and private properties in its quest to reduce runoff. While the city’s estimates suggest that the low-impact development approach will be more cost-effective than digging underground tunnels and expanding the capacity of sewage treatment plants, Philadelphia could still end up spending more than cities that followed the conventional path. But if Nutter’s plan succeeds, the city will have gained more than a network of underground sewage tunnels. Low-impact development promises to offer energy savings, create attractive green spaces, and reintroduce residents of the city to the water cycle. Only time will tell if the investment was worth the extra effort.


ps. I typed up the English myself, so errors are possible.


[美]戴·塞德拉克 著

徐向荣 等    虞左俊 校





Water 4.0: The Past, Present, and Future of the World's Most Vital Resource

Paperback:March 31, 2015

by David Sedlak (Author)

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