China’s capital is known for its horrendous smog and occasional sandstorms. Yet one of its major environmental threats lies underground: Beijing is sinking.
北京可怕的霧霾和偶爾發生的沙塵暴為世人皆知，而一個重要的環境威脅卻被大家忽略了：北京正在下沉。

Excessive pumping of groundwater is causing the geology under the city to collapse, according to a new study using satellite imagery that reveals parts of Beijing – particularly its central business district – are subsiding each year by as much as 11 centimetres, or more than four inches.
一項根據衛星圖像作出的最新研究結果顯示，過度抽取地下水導致北京地下結構出現塌陷。北京部分地區，特別是中央商務區，每年下沉多達11厘米，也就是超過4英寸。

The authors of the study warn that continued subsidence poses a safety threat to the city of more than 2o million, with “a strong impact on train operations” one of the predictions.
研究報告的作者提醒說，持續的下沉對這座人口超過兩千萬的城市構成安全威脅，其中一個預測就是“將對鐵路運營造成很大影響”。

The study on Beijing’s subsidence has been published in the peer-reviewed journal Remote Sensing and is based on InSAR, a type of radar that monitors land elevation changes. It was written by a team of seven researchers.
這項有關北京下沉的研究發表在同行評議期刊《遙感科學》上，基于合成孔徑雷達干涉測量技術，這是一種監測陸地高程變化的雷達技術。研究小組有7人。

“We are currently carrying out a detailed analysis of the impacts of subsidence on critical infrastructure (eg high-speed railways) in the Beijing plain,” they said in an email to the Guardian. “Hopefully a paper summarising our findings will come out later this year.”
他們在給《衛報》的一封電郵中寫道：“我們目前正在進行一項北京平原地區地表下沉對關鍵基礎設施影響的詳細分析（比如高鐵）。希望能在今年晚些時候發表一份能概括我們研究結果的論文?！?/p>

Beijing sits in a dry plain where groundwater has accumulated over millennia. As wells are drilled and the water table drops, the underlying soil compacts, much like a dried-out sponge.
北京坐落于干燥的平原地區，地下水經過了數千年的累積。隨著鉆井抽取地下水，地下水位下降，地下的土壤更加緊密，就像干涸的海綿。

The study finds that the entire city is sinking but the subsidence is most pronounced in Beijing’s Chaoyang district, which has boomed since 1990 with skyscrapers, ringroads and other development. The researchers say the uneven nature of the subsidence in some areas poses risks to buildings and other infrastructure.
研究發現，整個城市都在下沉，而朝陽區下沉最嚴重。上世紀90年代以來，朝陽區繁榮發展，高樓大廈和環路不斷涌現。研究人員說，一些地區下沉不均勻的特性會對建筑物和其他基礎設置造成威脅。

Tens of thousands of water wells are thought to exist in and around Beijing, many of them used in farming and landscaping. The state has regulatory power over installation of wells but is inconsistent in applying it, according to one leading Chinese environmentalist.
據稱北京及周邊地區有數萬口水井，其中很多用于農田灌溉和綠化。國家對打井有監管權，但據一位領頭的環保人士說，實際執行情況并不理想。

“There are some rules but the enforcement is doubtful,” said Ma Jun, director of the Institute of Public and Environmental Affairs in Beijing. Ma said he wasn’t surprised subsidence was relatively high in the Chaoyang district given its rapid growth of recent decades. He expected it to keep moving east as the city sprawled in that direction.
公眾環境研究中心主任馬俊說：“有一些監管規則，但執行成效令人懷疑?！瘪R俊說他對朝陽區地表下沉速度更快并不驚訝。因為朝陽區近幾十年來發展非?？?。他預計隨著整個城市向東擴展，地表下沉將會繼續向東延伸。

China inaugurated a mega-engineering project aimed at mitigating Beijing’s water crisis. The state completed construction of the South-North Water Diversion.
中國實施了一項大型的工程項目來緩解北京的用水緊張，現已完成了南水北調工程的建設。

Even before the canal began delivering water, Beijing was easing up on some groundwater pumping. In January of 2015 the Chaoyang district announced plans to phase out 367 water wells, reducing the use of 10m cubic meters of underground water.
在南水北調工程開始通水之前，北京已經開始控制某些地區的地下水抽取。2015年1月，朝陽區宣布計劃停用367口水井，每年減少開采地下水千余萬立方米。

Experts say it is still too early to know if the canal’s water deliveries will help recharge the aquifer and slow Beijing’s rate of subsidence. In the meantime concerns about impacts to buildings and rail systems continue. To prevent derailments a 2015 study recommended that China ban new water wells near completed high-speed rail lines.
專家表示，想要知道南水北調能否幫助充盈含水層并減慢北京下沉的速度還為時尚早。在此期間，人們仍將擔心下沉對建筑物和鐵路系統的影響。為防止列車脫軌，2015年的一項研究建議中國禁止在已完工的高鐵軌道旁打井。

Other cities around the world are experiencing subsidence caused by excessive water pumping or other factors. Mexico City is sinking by up to 28cm a year and Jakarta is subsiding at a similar rate. Bangkok is dropping annually by as much as 12cm, similar to Beijing, according to the Remote Sensing researchers.
根據《遙感科學》的研究，世界上其他諸多城市也受到過度抽取地下水或其他因素導致的地表下沉的困擾。墨西哥城每年下沉多達28厘米，雅加達下沉速度類似。曼谷每年下沉多達12厘米，與北京類似。

英文來源：英國衛報
翻譯&編輯：yaning