Cruising the Mekong River, Mekong River Facts

The Mighty Mekong, with its origins at altitudes of more than 16,000 feet in the Tibetan Plateau, is the twelfth longest river in the world. The Mekong flows almost 2,700 miles through the Yunnan Province of China, Burma (Myanmar) Thailand, and Laos as the Upper Mekong, and through Cambodia and Vietnam as the Lower Basin of the Mekong River. The water flow can reach 500,000 cubic feet per second, which is about twice the flow of the Columbia River in the United States. But it is the tremendous amount of rainfall in the monsoon season that floods the lower basin, and the fertility and productivity that result from the annual flooding and receding of the Lower Basin in Cambodia that make exploring Cambodia such a fascinating experience by river. When you cruise Cambodia by riverboat, you get an intimate appreciation for the productivity of the Mekong River, the difficulties posed by its dynamic annual fluctuations, and the techniques used by the people to harness its resources, which remain little changed for the last 1,000 years.

If you cruise Cambodia on the Mekong River coming upstream from the Mekong Delta in Vietnam (which was Cambodian or “Khmer” territory for most of history until the French dominance of Indochine), you quickly arrive at the Cambodian capital of Phnom Penh, where the Mekong arrives from the north. Phnom Penh marks the beginning of the Mekong Delta, but it is also the confluence of Cambodia’s Sab River, which drains the critical Tonle Sap Lake that is the livelihood of central Cambodia. In fact, when exploring Cambodia you quickly learn that it is Tonle Sap Lake that dominates the Cambodian landscape, and which provides the incredibly fertile fisheries and the annually replenished mudflats that enabled the rice production for the great Khmer civilizations at Angkor Wat and the other temple cities of the Angkor Temple Complex.

If you cruise Cambodia on the Mekong River in the wet season between May and October, you’ll find that the river is actually flowing backward, upstream, and that is especially true on the Sab River into Tonle Sap Lake. The important concept to understand is that the wide, shallow delta of the Mekong cannot drain the immense wet season water flow from the mighty Mekong fast enough, so the water backs up like a bathtub with the drain plugged. As the bathtub of the Lower Basin fills, the banks of the Mekong River spill out across vast expanses, and the Tonle Sap Lake increases to a hundred miles in length. You can literally watch the Lower Basin of the Mekong filling up, by watching the water currents moving backward as it cannot drain out through the delta.

Rice cultivation and shallow water fisheries retreat with the advancing shoreline, then follow it back down again, planting rice in the newly exposed mudflats, fertilized with another year’s minerals and nutrients from the great Mekong drainage above.

It is this annual productivity that makes the Mekong River so extraordinary. And it is because the people still work the rice paddies, yoke the water buffalo, trap the shrimp, crabs, and fish, and live on stilted houses or in floating villages in the same way that they have for the last millennium, that make exploring Cambodia such an enlightening experience. When you cruise Cambodia, you see the landscape and the people from the source of its nourishment, the Mekong River, and when you cruise Cambodia, be sure to include a detour into the Sab River that connects Lake Tonle Sap to the Mekong, for it is one of the most interesting and culturally fascinating stretches of river left in the world.

Read up and gear up for your expedition with more of our staff articles for more Mekong River facts.

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