Many of you have heard of the scramble in China to catch the millions of displaced rats from the 3 Gorges Dam to serve in Gourmet Chinese eateries.

The rising water below the structure evicted the rodents from the banks of Dongting Lake, “a series of wetlands and lakes”, into neighbouring farmland, where they quickly decimated 6,000 square miles of crops.

Desperate farmers at first deployed poison, but that simply killed the cats and dogs “traditionally use to combat the menace”, while doing nothing to reduce rat numbers.

However, they soon realised there was another, money-making solution to the crisis – a “major uptake in supply and demand for rat meat”, reported by live food traders in Changde at the western edge of the lake. One dealer told local media: “People there [Guangdong] are rich and like to eat exotic things, so business is very good.”

The economics are as follows: farmers pocket around six to ten yuan a kilogram (20 to 35 pence a pound in old money, the Telegraph helpfully adds), while Cantonese restaurants knock it out as delicious rat stew for up to four quid a pound.

But while the solution to the problem may lie in part in Guangdong’s saucepans, the reasons behind the rat plague are rather more complex than a simple rise in water level. Initially, the Three Gorges Dam held back enough water from Dongting Lake’s “marshy banks” to create an improved environment for the animals and provoke a sharp population rise.

Simultaneously, a “sudden fashion” for snake meat in Hunan – with residents of the capital Changsha working their way through ten tons of reptile flesh a day, according to local environmental groups – has done for the rats’ main predator.

The whole sorry state of affairs is, these groups claim, fulfillment of their dire predictions about the environmental effects of the Three Gorges Dam project.

While there is clearly a humorous aspect to this story, the underlying story is very troubling.

The rat infestation is simply the first of many troubling manifestations of this.

The Yellow River is so named because it is Yellow. With no lakes for sediment to settle in, the river flows quickly, carrying its nutrient laden cargo to the ocean.

The periodic floods serve to replenish the breadbasket of China. The estuary is fertile ground, and the where many fish in Asia spawn.

The dam will change all that, and other things too, in unanticipated ways, like the rats in this story.