Thailand's Pollution Control Department reports divide the country into five main geographical regions: north, northeast, central, south, and east.[67] Thailand has a total of 25 river basins[68] in the country and Thailand's annual rainfall is around 1,700 mm. Despite the annual southwest monsoon, Thailand is subject to drought, particularly the northeastern region.[69] As of 2002, Thailand had less water available per person than any other country in Asia,