Countries

The Socialist Republic of Vietnam, located on the eastern coast of the Indochinese Peninsula, covers a surface area of 331 690 km² from latitude 9° to 23° N and longitude 102° to 110° E. It is bordered on the north by China, on the west by Laos and Cambodia and on the south and east by the South China Sea.

The country can be represented in a schematic way in the form of two plains, the delta of the Songkoi (Red) River in north and the delta of Mekong River in the south, connected by mountainous ridges between and the coastal plains of Annam:

• The Songkoi, as does the Mekong, has its source in south-west China. The whole of its area and that of its rivers of less importance covers an area of 1 500 000 hectares. The area of the delta is prone to frequent flooding.
• The Mekong delta covers 3 700 000 hectares and is formed by five branches of the Mekong and three secondary rivers, the Long Vam Co, the Song Sai Gon, and the Song Dong Nai. This plain is very fertile and mostly cultivated. The sediment deposited by the Mekong is so significant that the size of the delta increases by up to 80 meters per year. The low-lying areas on the coast and inland are covered with mangroves.
• The Annam Mountains constitute the southern spur of the mountains of central China and Tibet. The northern part in Viet Nam is narrow and very rugged. That part in the south constitutes the central plateau with mountains reaching 2 500 m.

  The northern mountains border China and at their highest exceed 3 000 m (Fan Si Pan, 3 143 m). Mountainous spurs that are topped by rocky outcrops break the narrow coastal plain between the two deltas. It has an average width of 16 km but widens, toward the south, to the vast plain of the Mekong.

Most of Viet Nam enjoys a tropical monsoonal climate. At Hue, which is practically in the middle of the country, the monthly average temperature varies between 20° C in January and 30° C in August, with an annual rainfall of 2 600 mm of which 1 650 mm occurs during the wet season of September through November.

The climate is generally hot and humid. In central and southern Vietnam, seasonal variations are slight. The average daily temperatures in the Mekong Delta range from 17° to 34° C in January and from 22° to 33° C in July. Along the central coast, temperatures range from 18° to 28° C in January and from 24° to 37° C in July.

The Songkoi delta is subject to cold north winds during the monsoon and has a cold season from December to March with temperatures of about 17° C in January and February. The average annual rainfall is about 1 680 mm in the Red River Delta, 1 650 mm along the central coast, and 1 980 mm in the Mekong Delta. Much of the rainfall occurs during the summer monsoon season. The central coast is subject to periodic typhoons.

The designations employed and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.