Tonle Sap (lake)
| Tonle Sap | |
|---|---|
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| Geographical location | Cambodia |
| Tributaries | Tonle Sap River , Siem Reap River |
| Drain | Tonle Sap River |
| Location close to the shore | Siem Reap , Battambang |
| Data | |
| Coordinates | 12 ° 52 '34 " N , 104 ° 4' 23" E |
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| Altitude above sea level | 0.5 meters |
| surface | 2,700-25,000 km² |
| length | 250 km (maximum) |
| width | 100 km (maximum) |
| volume | 80 km³ (maximum) |
| Maximum depth | 14 m |
| Middle deep | 2–3 m (minimal) |
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particularities |
largest lake in Southeast Asia |
The Tonle Sap Lake ( Khmer : បឹងទន្លេសាប , pronunciation : [ boeung tunleː saːp ]) in Cambodia is the largest lake in Southeast Asia and one of the most fish-rich inland waters on earth.
geography
The lake is fed from the north by several tributaries. In the south, the lake is connected to the Tonle Sap River , which forms the inflow or outflow in the seasonal change and flows further south in Phnom Penh into the Mekong .
Every year in June a natural phenomenon unique in the world can be observed there. At this time, the Mekong has up to four times more water than in the dry months due to the monsoon rains and the meltwater from the Himalayas . Since Cambodia is largely a very flat and level country, the water of the Mekong pushes into the Tonle Sap River, which then changes its direction of flow. At the end of this, the water masses now fill the basin of the lake. During the dry season it has a surface area of 2,600–3,000 km² until it grows to around 10,400 km² (including the surrounding river landscapes: up to 25,000 km²) and is up to five times as deep (from 2–3 m to 14 m) . The peak of the flooding will be reached in September. At this point in time, almost a third of Cambodia's arable land is covered by water.
Only in November, when the Mekong has less water again, does the river change direction again and the water of the lake slowly flows away. This event is the occasion for the so-called water festival (Khmer: Bon Om Touk ) , which also marks the beginning of the fishing season.
Economical meaning
For centuries, fishing and rice cultivation have been the main industries of the rural Cambodian population. Rice and fish are also the main ingredients of Khmer cuisine . And both are shaped by the annual rhythm of the Tonle Sap system.
traffic
The lake also serves as a traffic route. A speedboat connection connects the city of Siem Reap in the northeast of the Tonle Sap with the capital Phnom Penh in the south, and across the Sangke River, which flows into the lake in the northwest, with Battambang , the country's second largest city. Via the Mekong it is also possible to reach Vietnam and Laos by water. The Tonle Sap River and also the Tonle Sap Lake are important transport routes in this part of Cambodia. Due to the increasingly improved road conditions, however, the majority of goods and people are now transported by road.
rice
The annual floods from rivers and lakes guarantee irrigation and fertilization of the rice fields, which have to be irrigated through canal systems during the dry months.
fish
There are almost 200 species of fish in the Tonle Sap. The more common fish in the Tonle Sap which includes cross-striped snakehead ( Channa striata ) and the Great snakehead , the walking catfish , the Common helicopter Wels , the Asian pennant knife fish , the Siamese barb and carp species Cirrhinus microlepis , Henicorhynchus siamensis (Siamese mud carp) and Black Frans Lipper . The Mekong giant catfish is almost extinct in the lake , one of the largest freshwater fish in the world, weighing up to 250 kilograms. The few specimens that were still caught in the Tonle Sap were considerably smaller.
The main season for fishing begins in November when the amount of water in the lake slowly decreases again and the abundance of fish has reached its peak after the months of flooding. It is estimated that over 300,000 tons of fish are caught annually in Cambodia (including inshore fishing), the majority of it in inland waters and half of it in the Tonle Sap. Fish alone provides at least three quarters of the protein consumed in Cambodia .
Ecology and hazard
The Tonle Sap lake, together with the Tonle Sap , Mekong and Bassac rivers, forms a unique ecosystem that not only made possible the diversity of species (around 200 plant and 150 fish species, rare water birds, numerous water snakes, Siamese crocodiles, etc.) in the water and in the surrounding area but was also crucial for the development of the people living in the area and their culture.
The historical kingdoms of the Khmer with their center in Angkor , which is only a few kilometers north of the lake, would presumably not have arisen without the abundance of water and the abundance of food that goes with it.
Today, the structure of the seasonally changing spawning times, fishing, agricultural use and fertilization of the surrounding area is in danger.
overfishing
The lake is still one of the richest fish in the world, but the beginning industrial fishing is already showing its first effects and fishermen are reporting a decline in yields. Nylon nets, which, contrary to earlier traditions, are stretched across rivers, barely give fishermen the opportunity to catch fish themselves downstream. The methods change. Instead of throwing nets and traps made of wood, reed and bamboo, grenades, batteries or poison are sometimes used.
The decline in fishing yields and the increased need for meat for the nearby crocodile farms have led to an increasing number of water snakes, mainly specimens of the striped water snake ( Enhydris enhydris ), being fished out of the lake over the past two decades . There are currently around seven million pieces per year. As a result, the populations of these animals are also extremely endangered, as there is no closed season for the snakes even in the breeding season from November to December (see chapter film).
environmental pollution
Another problem is water pollution . The floods also bring fresh alluvial sand with them every year, which naturally fertilizes the fields. Today this alluvial sand is more and more polluted, especially with the sewage from the industrial plants located upstream on the Mekong in Thailand and the People's Republic of China . Agriculture and logging on the banks also affect the ecosystem.
Dams
As has already happened in many other developing and emerging countries with controversial consequences (see Arundhati Roy's essays on the Sardar Sarovar dam project in India) for the population and the environment, dams are also intended to accelerate economic development in Cambodia . Eight dams are planned (as of 1999) on the tributaries of the lake, three of them on tributaries of the Mekong and five more on smaller rivers. In addition, existing and other planned dams in neighboring countries threaten to disrupt the seasonal rhythm of the inland water system. The Mekong will in Laos be used for 56 dams in Vietnam for 36, Thailand is planning two more to the 39 already existing and to an irrigation project that million cubic meters would dehydrate the Mekong annually 12,000, and in the People's Republic of China should be a six more dams are to be built.
Movie
- 360 ° - Geo Reportage: Trapping snakes in Cambodia. Documentation, Germany, France, 52 min., 2007, a film by Thérèse Engels, production: ZDF , arte , first broadcast: December 29, 2007, content description by geo
- Cambodia's declining fish stocks - Report on Al Jazeera English from August 12, 2010 (video, English)
Web links
- Joe Cochrane: Troubled Waters. In: Newsweek . January 14, 2002
swell
- ↑ Species in Tonle Sap. FishBase .
- ^ Ian C. Campbell, Colin Poole, Wim Giesen, John Valbo-Jorgensen: Species diversity and ecology of Tonle Sap Great Lake, Cambodia. In: Aquatic Sciences. Vol. 68, No. 3, 2006, pp. 355-373.
- ^ The world's largest snake hunt ( Memento of December 14, 2007 in the Internet Archive ). In: New Scientist . No. 2611, July 7, 2007, p. 4.