The Phnom Penh Waterfront

In Phnom Penh the mighty Mekong River joins the Tonlee Sap River in an interesting natural partnership.

The Mekong drains out of China, Laos and Thailand. Its burden of water and silt naturally seek the river's outlet on the Vietnamese coast, but when monsoon rains fall, flood waters force their way into the center of Cambodia, reversing the flow of the Tonlee Sap River which otherwise drains the lake there. A vast flood plain forms and the Tonlee Sap Lake swells, doubling in size. However, as it grows counter-pressures increase. And every year, in a single day, the flow reverses allowing the water to rush back East to rejoin the Mekong at Phnom Penh and resume its interrupted journey to the Pacific.

Back in the center of the country, as water levels collapse farmers recapture previously flooded land in an annual ritual to grow a further crop of rice. This is probably the second most important natural rythmn in Cambodia. It is synchronized with the most important: the alternation of monsoon and dry season!

The Tonlee Sap: the only river in the world that reverses flow twice a year.

Cambodia. Always the same. Always something new. Like this sunset rainbow over the Tonlee Sap River. (The flags of every nation are represented there.)