Physical Geography

Several district regions make up Vietnam. They are Southern Lowland; the Annam Cordillera; the Coastal Plain; the Tonkin Lowland; and the Northern Highlands.

The Southern Lowland consists of the densely populated Mekong Delta and the adjacent area to the north. A low, fertile plain only slightly above sea level, it is one of Asia's great rice-producing regions.

The Annam Cordillera is a long mountain chain forming much of the Laos-Vietnam border. In the north the mountains are narrow and have rugged peaks reaching almost 9,000 feet (2,740 m) above sea level. The southern section spreads out to form the Central Highlands, a wide plateau ranging from 2,000 to 4,000 feet (610 to 1,220 m) in altitude, but with peaks up to 7,900 feet (2,410 m).

The Coastal Plain, lying between the Annam Cordillera and the sea, extends approximately from Nha Trang northward to Thanh Hoa. Narrow and in places disappearing altogether toward the south, the plain widens to 40 miles (60 km) in its northern portion.

The Tonkin Lowland is the heart of northern Vietnam. It includes the lower valley and delta of the Red River and the surrounding area. Like its counterpart, the Southern Lowland, it is a broad, flat region, thickly settled and intensively cultivated.

The Northern Highlands, bordering the Tonkin Lowland on its landward sides, occupy much of the wide portion of northern Vietnam. The highest peaks, exceeding 10,000 feet (3,050 m), are in the west and northwest. Most of the region's people live in the deep, narrow valleys of the Red River and its tributaries.

Vietnam has two great river systems: the Mekong in the south and the Red River in the north. Both have large delta plains that are subject to heavy seasonal flooding, and both are crossed by complex canal networks. Of the other rivers, the largest are the Ca and Ma, in the north, and the Dong Nai, in the south.

A tropical monsoon climate prevails, with warm to hot weather all year and heavy, though seasonal, rainfall. The summer monsoon brings moisture-laden air from the south that drops much rain everywhere except on the Coastal Plain. From June through September Ho Chi Minh City (Saigon) receives 50 inches (1,270 mm) of rain, Hanoi 45 inches (1,140 mm). The heaviest rains of the northeast winter monsoon, which begins in September, occur on the Coastal Plain. Hue, one of the cities on the plain, receives an annual average of 100 inches (2,540 mm) of rainfall, most of it during this monsoon.

Except in mountainous areas, high temperatures prevail all year. Ho Chi Minh City averages 79° F. (26° C.) in December, the coolest month, and 85° F. (29° C.) in April, the hottest. Hanoi has a January average of 62° F. (17° C.) and a June average of 85° F. (29° C.).

More than half the original forest that once covered Vietnam has long since vanished, largely because of cutting and burning to create new farmland. The remaining forest, chiefly in the mountains, consists of broadleaf evergreen and deciduous trees. Smaller patches of forest are scattered throughout the lowlands.