Cities pay price for drainage debt

HEAVY RAINS have brought serious flooding to many cities in the south of China since the region entered its annual rainy season in June. ThePaper.cn comments:

The rainstorms have caused considerable loss of life and damage to property, as they do year after year, as if the city flooding is an incurable urban disease.

In fact, the advancement of modern technology, as well as better urban planning and construction can provide solutions to the problem. For instance, building sponge cities, which are designed to absorb, clean and use rainfall in an ecologically friendly way that reduces dangerous and polluted runoff, or raising the capacity of urban drainage and water reservoir systems would be conducive to turning floodwater into useable water resources.

But both entail upgrading or even restructuring the underground pipe networks of cities, which is an expensive proposition, and more importantly, the underground projects are less visible than shiny skyscrapers, a symbol of achievement in the eyes of many city governors.

The drainage systems in most cities are designed and built according to an old urban construction standard that has remained unchanged for decades.

The rigidity of the standard makes the city designers and planners feel free to ignore the fact that the scale and complexity of cities today cannot be mentioned in the same breath as the ones when the standard was first drawn up.

As a result, the underground pipe systems, even in the most important parts of some cities, were designed for a heavy rain coming once every 10 years. But as extreme weather has become more frequent in recent years, some cities have experienced extraordinary rainfall a number of times in the past few years, when such an inundation used to happen once every 50 years or even 100 years. No wonder cities become paralyzed and laden with deathtraps, as water and electricity are a deadly mix, and submerged cars, open ditches and manholes－after the covers are washed away－also become killers.

Worse, many cities have ruined the original natural water systems such as lakes and rivers that offered flood control with large-scale urban construction projects. Take Wuhan, capital of Hubei province, for example, it used to be known as the city of a hundred lakes, but over the past 20 years, 70 percent of its lakes have given way to concrete, making the city vulnerable to flooding.

It is the time to repay the historical debt to better protect people's lives and properties. There must be a forward-looking plan, designed according to the heaviest rainfall that a city may encounter.