Chapter 5 - Geomorphology and Sedimentology of the Lower Mekong River

Abstract

This chapter provides an introduction to the geomorphology of the Lower Mekong River within a geological and physiographic setting. The Mekong River Basin can be divided into two units. The Upper Mekong Basin (or Lancang Jiang Basin) lies within China and the Lower Mekong Basin (LMB) lies to the south of the international border between China (Yunnan Province) and Laos (Lao PDR). In China, the Mekong River is known as the Lancang Jiang (“the turbulent river”), the headwaters of which drains from an altitude of 4970 m on the Tibetan Plateau and flow for nearly 800 km in Tibet before entering Yunnan province in China, where it flows for a further 1200 km. The mountains and hills of southern Yunnan, eastern Myanmar, northern Thailand, and Laos (Lao PDR) occupy an area between the eastern face of the Shan Plateau and the western part of the Indochinese peninsula. Elevations reach 2800 m and the mountains have a north-south alignment and, in the north, the valleys drain into the Mekong whilst, in the south, four large rivers drain to the Chao Phrya River in Thailand.