Of China's total farmland of 124 million hectares, only 57.8 million hectares, or 44 percent, can be irrigated, according to the Second National Agriculture Census released by the National Bureau of Statistics in February 2008.

Of the existing 87,085 reservoirs larger than 100,000 cubic meters, 86,258 were built between 1949 and 1979, and 827 were built after 1979. By the end of 2008, 37,000 reservoirs were obsolete and dangerous, accounting for 42.5 percent of the total, says the Ministry of Water Resources.