Exactly 200 years ago, a newly chosen King of Siam, Chao Phya Chakri, moved the capital of his kingdom to a marshy lowland where he thought his people could grow rice.
The birth of Bangkok, thus, coincided with the start of Thailand's longest-lasting monarchy. While the Chakri dynasty remains revered, the city long ago lost its agricultural purpose and today ranks with government bureaucracy as a major economic problem.
''How we solve Bangkok's urban ills will determine our future,'' says Dr. Snoh Unakul, secretary-general of the National Economic and Social Development Board.
Only 16 percent of Thailand is urbanized. But 60 percent of the urban population lives in Bangkok, which is 45 times as big as the next largest city, Chiang Mai.
Loss of productivity can be measured by the two-hour commutes -- mostly idling in traffic -- for many workers. Such a concentration of urban wealth creates large income disparities with the rural poor, and government officials find it difficult not to bend to urban demands.
Thai academics call it ''the diseconomies of agglomeration.''
What may be just as urgent a problem is Bangkok's ''sinking feeling.'' City wells drawing water out of the mud base are dropping the land by some four inches a year. During rainy periods, some city streets are flooded for days. Unless costly new water supplies are found and more canals dug, the city could be below sea level by the year 2,000.
With some 5 million people in Bangkok now, the government hopes to cap the population at just over 8 million by 1990. Then it hopes peasant drift to the city will be reversed. With foreign assistance, eight ''secondary'' cities are being developed. Over 3,000 ''illegal'' factories are listed for removal. An elevated expressway being built over the city center to relieve traffic congestion is nearing completion, and an elevated rail line has been approved. Also, trucks are banned on city streets during daytime.
Such measures are to buy time until the biggest alternative to Bangkok is developed, sometime in the 1990s. The Eastern Seaboard Project, as it is called, ''is our only hope,'' says the planning board's assistant secretary-general, Dr. Phisit Pakkasem.