384 



The Mekong is already large (1.200 feet wide) at the point where 

 it leaves China. However, it is further swelled by some 34 major trib- 

 utaries and countless smaller streams, so that perhaps as much as two- 

 thirds of the water that discharges from the mouth is contributed by 

 the lower drainage basin. The minimum flow of the river 190 miles 

 upstream from the mouth is twice that of the Columbia River at its 

 mouth, and its maximum flow is 30 to 40 times as great. 26 



From China to the sea the river descends about 1.000 feet. The de- 

 scent is uneven, with falls and rapids obstructing river traffic at Krai ie. 

 Khone Falls, and Khemmarat Rapids. Variation in flow is extreme: 

 much of the annual rainfall, of about 60 inches, occurs during the rainy 

 season, from May to October, when the flow of the river in the lower 

 basin increases 15- or 20-fold from low water to flood season. 



Although the flat lands of the Mekong Delta are intensively culti- 

 vated (mostly in rice), much of the rest of the region is predominantly 

 forest, with most of the farming along watercourses. River transpor- 

 tation is the principal form of freight movement, with few roads or 

 rail connections; in the Delta, a network of some 8,000 miles of canals 

 has been dredged. From the sea, ocean vessels can navigate upriver 

 190 miles from Phnom Penh; coastal vessels can reach another 80 

 miles. River vessels can also ply the river on the long stretches of 

 more placid water upstream. 



Complex Social and ( 'ultural Patterns of the Basin 



The four Riparian States present considerable racial, linguistic, 

 and religious complexity. Educational levels are low (typically, four 

 years of schooling). Standards of health and hygiene arc 1 generally 

 poor, with a heavy incidence of malaria and waterborne infections. 

 Incomes are low, but despite the generally primitive level of subsist- 

 ence agriculture, food supplies appear to be adequate. Populations in 

 these countries have tripled in the past half-century; accordingly. 

 with high birth rates and short life expectancy, the populations are 

 extremely young (60 percent under 25 years of age). The very young 

 and old people live mostly in rural villages, while young adults and 

 the middle-aged, the most numerous segment, congregate in urban 

 areas. 



The four nations have had a long and complicated history of politi- 

 cal and military interactions. There have been incessant and disjointed 

 conflicts of aggression, frequent internal power struggles, expansions 

 and contractions of territory, waves of invasion from the north, cul- 

 tural penet i at ion from India, and economic penet rat ion mainly by the 

 French. Colonial administration by the French lias left important ef- 

 fects in Cambodia, Laos, and Vietnam. A sharp break in the continuity 

 of balkanization occurred, L941 L945, with the Japanese invasion. 

 Thailand bowed to the inevitable, allying itself with Japan, while the 

 other three states were overrun; with the end of World War II. all 

 four states were faced with the need for extensive political and eco 

 nomic adjustment. Following expulsion of the Japanese, these adjust- 

 ments began with expulsion of the French, followed by an interaction 

 of economic, ocial, political, and religious developments too com 



;ures of water flow :it various points on Hip Mekong and at various seasons. 01 

 different years, varj widely from one source to nnother. It Is rleai from all of these 

 the river is i n * l I extremely large, but precisely how large Is hard to say. 



