Resuscitating rivers

URBAN ECOSYSTEMS

For half a century, a dark tunnel of crumbling concrete encased more than three miles of a placid stream bisecting this bustling city. The waterway had been a centrepiece of Seoul since kings of the Choson dynasty selected their new capital 600 years ago, enticed by the graceful meandering of the stream and its 23 tributaries. But in the industrial era after the Korean War, the stream, by then an open sewer, was entombed by pavement and forgotten beneath a lacework of elevated expressways as the population swelled toward 10 million.

Today, after a $384 million recovery project, the stream, called Cheonggyecheon, is liberated from its dank sheath and burbles between reedy banks. Picnickers cool their bare feet in its filtered water, and carp swim in its tranquil pools.

The restoration of the Cheonggyecheon is part of an expanding environmental effort in cities around the world to “daylight” rivers and streams by peeling back pavement that was built to bolster commerce and serve automobile traffic decades ago.

In Yonkers, NY., a long-stalled revival effort for the city’s ailing downtown core that could break ground this fall includes a plan to re-expose 1,900 feet of the Saw Mill River, which runs through a giant flume that was laid beneath city streets in the 1920s.

Breathing life into rivers
Cities from San Antonio to Singapore have been resuscitating rivers and turning storm drains into streams. In Los Angeles, residents’ groups and some elected officials are looking anew at buried or concrete-lined creeks as assets, inspired partly by Seoul’s example.

By building new green corridors around the exposed waters, cities hope to attract affluent and educated workers and residents who appreciate the feel of a natural environment in an urban setting.

Environmentalists point out other benefits. Open watercourses handle flooding rains better than buried sewers, a big consideration as global warming leads to heavier downpours. The streams also tend to cool areas overheated by sun-baked asphalt and to nourish greenery that lures wildlife as well as pedestrians.

Some political opponents have derided Seoul’s remade stream as a costly folly, given that nearly all of the water flowing between its banks on a typical day is pumped there artificially from the Han River through seven miles of pipe.

Environmental benefits are many
But four years after the stream was uncovered, city officials say, the environmental benefits can now be quantified. Data show that the ecosystem along the Cheonggyecheon (pronounced chung-gye-chun) has been greatly enriched, with the number of fish species increasing to 25 from four. Bird species have multiplied to 36 from six, and insect species to 192 from 15.

The recovery project, which removed three miles of elevated highway as well, also substantially cut air pollution from cars along the corridor and reduced air temperatures.

Small-particle air pollution along the corridor dropped to 48 micrograms per cubic meter from 74, and summer temperatures are now often 5 degrees cooler than those of nearby areas, according to data cited by city officials.

And even with the loss of some vehicle lanes, traffic speeds have picked up because of related transportation changes like expanded bus service, restrictions on cars and higher parking fees.

“We’ve basically gone from a car-oriented city to a human-oriented city,” said Lee In-keun, Seoul’s assistant mayor for infrastructure, who has been invited to places as distant as Los Angeles to describe the project to other urban planners.

Some 90,000 pedestrians visit the stream banks on an average day. What is more, a new analysis by researchers at the University of California, Berkeley, found that replacing a highway in Seoul with a walkable greenway caused nearby homes to sell at a premium after years of going for bargain prices by comparison with outlying properties.

Recovering urban waterways
Efforts to recover urban waterways are nonetheless fraught with challenges, like convincing local business owners wedded to existing streetscapes that economic benefits can come from a green makeover.

Yet today the visitors to the Cheonggyecheon’s banks include merchants from some of the thousands of nearby shops who were among the project’s biggest opponents early on.

On a recent evening, picnickers along the waterway included Yeon Yeong-san, 63, who runs a sporting apparel shop with his wife, Lee Geum-hwa, 56, in the adjacent Pyeonghwa Market.

Yeon said his family moved to downtown Seoul in the late 1940s, and he has been running the business for four decades. He said parking was now harder for his customers.

But “because of less traffic, we have better air and nature,” he said. Yeon and his wife walk along the stream every day, he added. “We did not think about exercising here when the stream was buried underground.”

The role of Seoul’s environmental renewal in Lee’s political ascent is not lost on Mayor Philip A Amicone of Yonkers, a city of 200,000 where entrenched poverty had slowed a revival project.

Once the river restoration was added to the plan, he said, he found new support for redevelopment.

Yonkers has gained $34 million in money from the state of New York and enthusiastic support from environmental groups for the river restoration, which is part of a proposed $1.5 billion development that includes a minor-league baseball ballpark. The river portion is expected to cost $42 million overall.

NYT News Service