Monday, April 22, 2013

Resilient communities in the floodplain of Cambodia's Tonle Sap Lake

Cambodia's Tonle Sap Lake is the largest freshwater lake in Southeast Asia. During most of the year, the lake is fairly small with depths of about one meter deep and an area of 2,700 square km.  However, during the rainy season, overflow from the Mekong River causes the lake to swell to 15,000 square km with a depth up to nine meters (Wikipedia,

Thousands of families, many of whom are ethnic Vietnamese, live year round on houseboats, making their living from fishing.  Even more Khmer communities are located in the floodplain of the Tonle Sap. 

Most of the year, when the lake is low (roughly November through July), these floodplain communities are located on dry land.  However, homes are built up high on stilts that are several meters tall in preparation for the annual rise of the lake.

During a recent dry season visit to some of these Tonle Sap floodplain communities near Siem Reap, we learned that planks used for floors in these homes can be adjusted higher depending on the water levels.

During the dry season, the residents of the floodplain communities continue to catch fish from the lake to sell, generally preserving their catches through drying,smoking or fermentation.  But many also supplement their food and income by raising vegetable gardens in the organic matter rich soil around their homes.  Luffa gourd, with edible fruit and shoots, and eggplant the most commonly grown vegetables in these gardens.  And water spinach (Ipomoea aquatica) grows in practically all moist locations.

In addition to the dry season garden patches, most of the elevated households also had container gardens.  Small plantings of herbs and vegetable, as well as papayas, are grown in various types of containers, allowing for production even when the lake again surrounds the houses.  The frequency and extent of container gardening among these Tonle Sap households was greater than any other complex of communities that I have visited. 

We also observed that some families also have pigpens located beneath their houses.  They generally feed their pigs cooked water spinach, rice bran and food scraps.  Interestingly, it was explained to us that some of the pigpens were actually pig rafts, under which drums are attached for flotation when high waters eventually return.   

As the water table in the flood plain is quite high, access to water for irrigating small garden patches and watering pigs isn't much of a problem.  However, the dirty water is also used for other household purposes, such as washing dishes, laundry and drinking water.  Of course, waterborne disease is a major concern since, as our guide reported, many of the residents do not either boil or filter their water.  Fortunately, one home that we visited had a ceramic water filter that does an excellent job of filtering dirt, debris and bacteria from the water.

Although the Tonle Sap supports the aquatic livelihood of many thousands of Cambodian families, it is a challenging environment in which to live and work, requiring adaptability and resilience by the locals. 

But perhaps the greatest challenge for the Tonle Sap ecosystem and its human residents will be the effects of 42 dams that are proposed to be built along the Mekong and its tributaries that would inevitably affect the flow of water into this natural wonder.  In addition, the effects of climate change are expected to bring greater variation to the water levels of the Tonle Sap, as well as changed seasonal shifts in water level patterns.

Therefore the already resilient communities of the Tonle Sap may need even more adaptability and preparation for a very uncertain future.

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