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Posts tagged Tonlé Sap River

Phnom Penh on Banks of Mekong River, Cambodia

11.5N 104.9E

December 28th, 2011 Category: Rivers

Cambodia - December 24th, 2011

This APM image shows the city of Phnom Penh, the capital and largest city of Cambodia, located on the banks of the Mekong River. The municipality extends over a larger area, and is situated on the banks of the Tonlé Sap, Mekong, and Bassac rivers.

The city covers an area of 678.46 square kilometres (262 sq mi), with some 11,401 hectares (28,172 acres) in the municipality. The agricultural land in the municipality amounts to 34.685 square kilometres (13 sq mi) with some 1.476 square kilometres (365 acres) under irrigation. Phnom Penh and the surrounding areas consist of the typical wet plain area for Cambodia.

The Combined Lake and River System of the Tonlé Sap, Cambodia

12.9N 104.0E

February 16th, 2010 Category: Lakes, Rivers, Sediments

Thailand, Cambodia and Laos - January 26th, 2010

Thailand, Cambodia and Laos - January 26th, 2010

The Tonlé Sap, southwest of the image center, is a combined lake and river system of huge importance to Cambodia. It is the largest freshwater lake in Souteast Asia (Cambodia, eastern Thailand and southern Laos are all visible here) and is an ecological hot spot that was designated as a UNESCO biosphere in 1997.

The Tonlé Sap is unusual for two reasons: 1) its flow changes direction twice a year, and 2) 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 the 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 3 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.

National and local observers often state that the Tonlé Sap Lake is rapidly filling with sediment, as can be observed from its tan color here. However, recent long-term sedimentation studies show that net sedimentation within the lake proper has been in the range of 0.1-0.16 mm/year since ca. 5500 years before present (BP). Thus, there is no threat of the lake filling up with sediment. On the contrary, some say, sediment is not a threat to the lake but an important part of its ecosystem, providing nutrients that drive the floodplain productivity.