The Tonlé Sap is the largest freshwater lake in South East Asia and is unusual for two reasons: its flow changes direction twice a year, and the portion that forms the lake expands and shrinks dramatically with the seasons. From November to May, Cambodia's dry season, the Tonlé Sap drains into the Mekong River at Phnom Penh. However, when the year's heavy rains begin in June, the Tonlé Sap backs up to form an enormous lake. For most of the year the lake is fairly small, around one meter deep and with an area of 2,700 square km. During the monsoon season, however, the Tonlé Sap river, which connects the lake with the Mekong river, reverses its flow. Water is pushed up from the Mekong into the lake, increasing its area to 16,000 square km and its depth to up to nine meters, flooding nearby fields and forests. The pulsing system with its large floodplain, rich biodiversity, and high annual sediment and nutrient fluxes from Mekong makes the Tonlé Sap one of the most productive inland fisheries in the world, supporting over three million people and providing over 75% of Cambodia's annual inland fish catch and 60% of Cambodians' protein intake. At the end of the rainy season, the flow reverses and the fish are carried downriver. The reversal of the Tonlé Sap river's flow also acts as a safety valve to prevent flooding further downstream. During the dry season the Tonlé Sap Lake provides around 50% of the flow to the Mekong Delta in Vietnam. (Special thanks to Wikipedia for language and facts.)
Sunday, April 17, 2011
The Tonlé Sap is the largest freshwater lake in South East Asia and is unusual for two reasons: its flow changes direction twice a year, and the portion that forms the lake expands and shrinks dramatically with the seasons. From November to May, Cambodia's dry season, the Tonlé Sap drains into the Mekong River at Phnom Penh. However, when the year's heavy rains begin in June, the Tonlé Sap backs up to form an enormous lake. For most of the year the lake is fairly small, around one meter deep and with an area of 2,700 square km. During the monsoon season, however, the Tonlé Sap river, which connects the lake with the Mekong river, reverses its flow. Water is pushed up from the Mekong into the lake, increasing its area to 16,000 square km and its depth to up to nine meters, flooding nearby fields and forests. The pulsing system with its large floodplain, rich biodiversity, and high annual sediment and nutrient fluxes from Mekong makes the Tonlé Sap one of the most productive inland fisheries in the world, supporting over three million people and providing over 75% of Cambodia's annual inland fish catch and 60% of Cambodians' protein intake. At the end of the rainy season, the flow reverses and the fish are carried downriver. The reversal of the Tonlé Sap river's flow also acts as a safety valve to prevent flooding further downstream. During the dry season the Tonlé Sap Lake provides around 50% of the flow to the Mekong Delta in Vietnam. (Special thanks to Wikipedia for language and facts.)
