Floating communities’ adaptation to environmental changes
- Tonle Sap Lake, Cambodia

Tonle Sap Lake environment

Tonle Sap Lake is the largest freshwater lake in South East Asia. The lake’s tremendous natural capital provides food security, supports people’s lives and forms their cultural identity throughout Cambodia. The hydrological cycle of the lake is unique due to a reverse flood pulse into the lake during the peak flood season (May–June) when the discharge from the lake is almost completely blocked by the flood pulse through the Tonle Sap River, and the water surface of the lake expands five to six-fold before the flow in the Mekong River starts to subside (September-October). The flood pulse brings in a huge mass of water, sediments, nutrients and migratory fish, inundating vast areas of forests (i.e., flooded forests), wetlands, grassland and fields. The inundation provides sanctuary and breeding grounds for the migratory fish and other aquatic organisms as well as terrestrial wildlife such as birds, reptiles and mammals.

The lake is under multiple pressures from population growth, development activities, forest degradation, land cover changes, exploitation of its resources, and disposal of waste. External threats such as climate change and unwise development of a cascade of dams in upstream countries are found to seriously disrupt the unique flood-pulse system and threaten inflow of water, sediments, nutrients and migratory aquatic animals. Escalation of negative impacts on the lake’s ecosystem and environment might eventually be linked to increasing poverty and vulnerability of the people who are directly dependent on the lake resources for their livelihoods.

Enhancing resilience of communities living under traditional nature-based floating and water-land based villages

About 1.7 million people are living in over 1000 villages by the lake and on surrounding floodplains. People in these villages are fully water based (or floating villages), water-land based (living in stilt houses that resemble a floating village), and land-based. Floating houses or stilt houses and their lifestyles represent traditional nature-based solutions. The boats are used as the principal mode of transportation for fishing, business, as well as access to public and private facilities (health care facilities, markets, schools etc.) and interaction with other villagers. Floating villages are mobile throughout the year, and their communities depend on the lake in their day-to-day activities. It is where they drink water, cook food, wash clothes, bathe, and dispose of waste. In water-land based villages, people live on stilt houses built several meters above the ground. People spend nearly half the year on land during the dry season and half on water during the wet season, when floodwater surrounds the stilt houses. During the flooding season, they resemble water-based floating villages.

As a traditional nature-based solution, floating villages and people living in stilt houses are the living examples of harmonious coexistence between people and the natural lake environment. People living here are well adapted to the hydrological and ecological condition of the lake. Due to their heavy reliance on the lake’s resources they are highly vulnerable to hydrological changes in the lake, degradation of flooded forests and ecosystem and pollution. Surveys conducted in floating and land-based villages found that fishing comprises the primary or secondary source of income with a typical range of between USD 3 to 20 /day. Communities are experiencing decreased fish catches caused by reportedly shallower than typical water levels (i.e. 9-10 meters) during the peak flooding season, with the deeper water being ideal for a normal to good harvest. The rapid fall in quantity and quality of fish catch is taking its toll on household income and essential expenses. Meanwhile, sudden high waves caused by heavy storms add new challenges to small-scale fishing activities and houses in floating villages and water-land based villages. The higher tides could also damage and displace floating houses.

In the floating villages, where proper drinking water, sanitation and hygiene (WASH) and waste disposal are lacking, deterioration of water quality and frequent water-borne diseases, especially among children, through primary or secondary contamination paths are common.

Although the lifestyle of people living in the floating villages are nature-based, it is evident that the communities could not be sustained without additional resilience enhancement measures. Field studies, water quality surveys, lab analysis and hydrodynamic modeling under the SATREPS project [Establishment of Environmental Conservation Platform of Tonle Sap Lake] found awareness and provisioning of safer WASH alternatives, pollution control measures, alternative income other than fishing, and climate resilient aquaculture and farming are key for improving the resilience of these communities. Maintaining a healthy environmental condition in the lake, in flooded forests, and on farm land is therefore indispensable to ensure a sustainable and harmonious balance among aquatic ecosystems, rich biodiversity, and livelihoods of the local residents.

Creating Science-Policy-Community Interface

The Platform for Aquatic Ecosystem Research (PAER), which is the main outcome of the SATREPS project, has been established. This works as an information platform to support creating a science-policy-community interface. Given the sheer size of the lake and related inter-linkages, scientific research and tools are expected to support policy decisions with the full participation of the concerned communities. Such an interface is critical to identify robust resilience enhancement measures to overcome the challenges faced by the communities living in floating villages and stilt houses while addressing underlying drivers and pressures.