European Stars and Stripes (Newspaper) - September 04, 1985, Darmstadt, Hesse                                Page 16 the stars and stripes wednesday september 4, 1985 Many of world s big cities have that sinking feeling by Joy Aschenbach National geographic London is sinking. So Are Tokyo Bangkok Shanghai Houston new Orleans and even landlocked Mexico City and Las vegas. Mere than a dozen of the world s great cities Aie slowly sinking into the lands on which they were built some at worrisome rates dropping As much As a foot a year. Most Are sagging not under their own weight but because so much ground water has been pumped out from under them. Most Are located in co Al areas sitting on soft Sana Silt or Clay the kind of soil that easily compacts when Large volumes of water Are withdrawn. Compounding the sinking situation is the global Rise in sea Levels up to a foot or More a Century which raises the risk of flooding for some cities. Although cities have been sinking for centuries the problem has worsened in the past 40 years according to geologists Robert Dolan and Gant Goodell of the University of Virginia s environmental sciences department. The unprecedented demand for water Lor people and Industry has tapped the cheapest source the ground beneath our feet. When Clatl sink buildings crack or drop unevenly and streets and sidewalks buckle. People used to live with it. As structures Sank they d build on top of them or move away Dolan says Thor o an ancient Church in Italy s to Valley that has three sets of columns the first set is now in the basement under water. But modern life complicates matters. New construction is expensive. Land values Are High. Subways sewers and often Utility lines Are underground so you can t afford sudden variations in land Levels. Also Over the centuries Many structures have become historical treasures and can t be moved from their threatened  Venice a classic Case of a City already partially submerged by the sea. Increased its rate of sinking tenfold Between 1950 and 1970 by withdrawing ground water at a time of sea level Rise. As a result the chemical pollution in the venetian Lagoon has become a serious threat decaying the sinking cities �1wj National Leo graphic society i Mart thin a dozen of the world great it that from London to Tokyo Houston to Bangkok Are slowly sinking into the lands on which they Ware built. Base of buildings. London s renowned big Ben Tower now under repair was cracked and leaning about 18 inches because the City has been sinking along the thames about a foot a Century. The $1 billion thames Barrier completed last year is designed to control storm surge trom the big Lush Channel and prevent London s vital subway system from flooding. Because of the continued sinking of the City the Barrier 10 movable Gates built Side by Side across the River is estimated to be effective for about 100 years. Step off the curb in Mexico City and you May step Down More than a foot in some places. The world s largest megalopolis built 7,347 feet up on a Lake bed is a rare example of an Inland sinking City. It drops As much As 10 inches a year. The big problem is that the land does not All go Down together Dolan says. This differential subsidence has sunk some buildings a few feet and some from 18 to 25  the famous Al Angel Monument when too much of the water needed for Urban development i pumped trom the ground be Neath pressure within the toll decrease and the ground water layer compacts. Erected in 1910 for Mexico s Centennial of Independence appears to be ascending into the sky As the buildings and streets around it sink. Every few years a new Stair step has to be added to its Pedestal. Al Angel itself like other structures in the City rests on pilings set deep in solid ground. The anti a thai capital of Bangkok is in danger of falling below sea level by the year 2000. The water table that keeps the City afloat has dropped severely because of some 11,000 Wells needed for drinking water. Bangkok has sunk nearly three feet in the past 30 years and recently that rate has accelerated in some sections of the City. A number of . Cities from Savannah ga., to Long Beach calif., Are in various states of depression. Some Are slight such As Las vegas which is being pulled Down because the enormous weight of the water trapped in Lake Mead by the Hoover dam is depressing the Earth s crust. Two of the worst cases Are Houston and new Orleans. Houston is a textbook Ca a of Man s Impact on the environment Dolan says Low coastal area soft sediments Clay and san rapid industrialization explosive population and urbanization and the dredging of a big ship  Asa result of its Texas size thirst for ground water the nation s fourth largest City has sunk Lour feet in the past 80 years and its Western Section to expected to sink Lour Leal in the next 20 years. To the East whole neighbourhoods in the Baytown area along the Houston ship Channel have been abandoned to  Eston Bay. Sinking is an almost inevitable consequence of Industrial expansion Goodell says. Ironically development occurs where ground water is available and cheap. New Orleans is so soggy that millions of Gallons of seep water must be drained from it each Day. About 45 percent of the City is at or below sea level. The super dome is supported by 2,266 Concrete piles driven Down More than 150 Leet. Unlike Houston new Orleans is sinking irom Long term natural subsidence. No one sat around a conference table some 260 years ago and discussed the variables in developing the site Dolan says. Now we have to defend it and save  almost All sinking cities have taken some Steps to control ground water withdrawals and a number also have constructed enormous engineering works to do everything from Lessen the threat of flooding to prop up sagging and leaning buildings. But even in cities where sinking has been slowed or stopped there has been almost no recovery in ground Elevation the two geologists have discovered. Additionally at Ruk today Goodell says Are developing third world cities such As Bangladesh s capital Dacca that cannot afford the Cost of Long distance water. One of the greatest engineering and social challenges of the next Century will be How to save sinking cities he says. The stagger Long solutions Range from raising the cities by filling soil behind dikes to packing up and moving them to higher ground