Population in the Chao Phraya

"The Chao Phraya basin is the most important basin in Thailand. The Basin covers 30% of Thailand's land area, is home to 40% of the country's population, employs 78% of its work force, and generates 66% of its Gross Domestic Product (GDP). The total population of the Chao Phraya basin was 23.0 million inhabitants in 1996. The Basin can be divided into eight sub-basins based on the natural distribution of its river system. About 50% of this population (11.5 million) resides in the Lower Chao Phraya basin, in which the highly populated areas of Bangkok Metropolitan Area (BMA) and its environs of Samut Prakan, Nonthaburi and Pathum Thani are located. Similarly there is a large concentration of population in the Upper Ping where Chiang Mai (the second largest city in Thailand) is located. Overall, about 68% of the total population of the Basin is rural, but there is considerable variation with over 90% of the population being rural in the Upper Chao Phraya basin compared to 45% in the Lower Chao Phraya basin, It is projected in the next decade that the rural population will decrease by an annual rate of about 1.31% and that the population growth rate will remain low at about 1.0% per annum. These trends should ultimately induce aggregation of farming land with consequential increase in household incomes. Population density averages 136 persons/km2, but varies greatly from 44/km2 in the Nan Sub-basin to 533/km2 in the Chao Phraya Sub-basin. Bangkok and its vicinity have the highest population density of 1,497 inhabitants/km2."

from http://www.unesco.org/water/wwap/case_studies/chao_phraya/index.shtml