Some economic booms grind to a halt, others run out of steam, but in China the biggest risk is that growth will dry up. Water, the country's scarcest resource, is running out. Pollution, waste and over-exploitation have combined with the expansion of mega-cities to foul up wells and suck rivers dry.
Signs of a crisis are apparent everywhere. In the arid north, four-fifths of the wetlands along the region's biggest river system have dried up. In the west, desert sands are encroaching on many cities. In the south, the worst drought in 50 years has ruined crops and prompted water shortages even along the banks of the Yangtze River, the nation's biggest waterway.
Domestic newspapers are increasingly filled with grim statistics and reports of the latest pollution spill. In June, the state environment protection agency estimated that 90 percent of urban water supplies were contaminated with organic or industrial waste. According to the water resources ministry, 400 of the country's 600 cities are short of water.
Water has always been China's Achilles heel. The world's most populous country has per capita water resources of 2,200m3 -- less than a quarter of the world average. The shortfall between supply and demand is estimated at 6 billion cubic meters. The gap is likely to widen as the population grows from 1.3 billion people to an estimated 1.6 billion by 2030.
Worsening the problem is the stark regional variation between the dry north and the wet south. Beijing -- one of 110 cities deemed to suffer from "extreme shortages" -- has been forced to import supplies from a widening circle of sources.
In short, China's development model is unsustainable. For the past 30 years the government has emphasized the quantity rather than the quality of growth. Spectacular expansion figures of almost 10 percent a year mask dire inefficiency and environmental damage. For most of the past 30 years, financial resources have been invested in new factories rather than treatment plants, water recycling facilities or replacements for leaky pipes.
Only 52 percent of the country's 2 billion cubic meters of sewage is treated before it goes into rivers and lakes. This has expensive health implications. Each year, filthy water is a big factor in the 800 million cases of diarrhea, 650,000 cases of dysentery and 500 million cases of intestinal worms.
Industrial pollution creates political as well as physical concerns. Suspicions are rife that factory owners collaborate with government officials to cover up toxic spills in the interests of social stability and economic growth. But China's water crisis is not only the responsibility of officials and developers. Scientists blame global warming for the shrinking of glaciers and the disappearance of thousands of lakes in the Himalayas and other mountain regions in the west of China.
Climate change is also thought to have contributed to the worst drought in 50 years in Chongqing and Sichuan. No rain has fallen for 10 weeks and two-thirds of the rivers have dried up. Worse may be yet to come.
The head of the China Meteorological Administration has told China Energy Weekly that global warming will lead to shortages of 20 billion cubic meters of water in western China by 2030. There are signs that the government is taking these warnings more seriously.