The Great Reversal

Once a year a river turns and a lake grows several times its size. Everything around the Tonle Sap is arranged by that reversal.

In the monsoon the Mekong swells and pushes water back into the lake; in the dry season the lake drains out again and the river runs the other way. The movement builds and erases islands and channels every year, and leaves ground for a season's farming. The flooded forest that the flood covers is the nursery of the fishery. The villages stand on stilts or float. The roads are seasonal and often underwater, so the boats are the roads. The Khmer read this pulse centuries ago and built a civilization on it.

The pressures on the system — on its farming, its fishing, its productive life — are now being studied directly: not to prescribe, but to measure what the conditions are and what follows from them. Where the film names a cost, it names the mechanism. To clear the ground the stubble is burned; the cost is the smoke, and the soil the fire strips into the lake. Forest, village, temple, field — all of it set by the rise and fall of one lake.

The other chapters

The Sealed Waters — the karstic waters of Ha Long and Tam Coc.
The Long Threshold — the lagoons of Hue.