Oceanography of the Mekong River estuary

Abstract

The 4,800 km long Mekong River drains an area of 0.795 10^6 km^2. The river forms a delta downstream of Kompong Cham, Cambodia, where the river discharge varies seasonally between typically 2,100 m^3 s^-1 in April (the low-flow season) and 40,000 m^3 s^-1 in September (the high-flow season). The delta is drained by main channels that have a thalweg about 10m deep in the freshwater region located 30 km upstream from the mouth. Closer to the mouth, saline oceanic water intrude in the low-flow season, and the depth decreases to typically 5 m in the thalweg, with extensive shoals on either side. Even shallower waters are found in coastal waters near the mouth.

The sediment discharge is about 160 10^6 tonnes year^-1. To place the Mekong in perspective with other major rivers, the Mekong River has a smaller drainage area than the Yangtze (41%), the Amazon (12%), the Mississippi (24%) and the Ganges-Brahmaputra (53%) rivers. However the Mekong River sediment load is about the same as that of the Mississippi, it is 85% that of the Yangtze River and it is 12% larger than that of the Amazon.