The Tonle Sap Ecosystem

The Tonle Sap is one of the most critical freshwater ecosystems in the Mekong River Basin. It is the largest lake in South East Asia, home to a UNESCO Biosphere Reserve, a Ramsar site, and the most important inland fishery in Cambodia. The Mekong’s flood pulse is the primary driver of not only the floodplain’s hydrology, but also of its chemical, biological, and agricultural cycles.

The Tonle Sap floodplain is covered with a mosaic of habitats that provide shelter and food to both aquatic and terrestrial biota. These habitats are quite diverse in appearance and structure, including gallery forests, grasslands, shrublands, and rice fields. 

These are the main questions that we are addressing in this component of the project:

  • Can we link the distribution and characteristics of these habitats to the lake’s hydrology?

  • If so, can we predict changes in the floodplain vegetation cover as a result of future scenarios (hydropower, water abstractions, climate change) in the Mekong River Basin? 


 This investigation was carried out in 3 phases.
  1. a modeling approach to predict vegetation cover as a function of flood duration was developed using remote sensing data, long term hydrological records, and geographical information systems databases (See PULSEHAB page)

  2. a field survey was carried out to investigate the linkages among hydrological, soils, and vegetation characteristics throughout the floodplain.

  3. a numerical simulations using the 3D EIA model were carried out to assess the impact of scenarios of water resources development and climate change on sedimentation and aquatic primary production.


 View the four main types of vegetation of the Tonle Sap in these videos:



Arias, M.E., Cochrane, T.A., Kummu, M., Lauri, H., Koponen, J., Holtgrieve, G.W., Piman, T. (2014) Impacts of hydropower and climate change on drivers of ecological productivity of Southeast Asia’s most important wetland. Ecological Modelling 272C 252-263, DOI: 10.1016/j.ecolmodel.2013.10.015.

Arias, M.E., Cochrane, T.A., Elliott, V. (2013) Modelling future changes of habitat and fauna in the Tonle Sap wetland of the Mekong.  Environmental Conservation,  doi:10.1017/S0376892913000283.

Arias, M.E., Cochrane, T.A., Norton, D., Killeen, T.J., and Khon, P. (2013). The flood pulse as the underlying driver of vegetation in the largest fishery of the Mekong Basin. AMBIO, DOI 10.1007/s13280-013-0424-4

Arias, M.E., Cochrane, T.A., Piman, T., Kummu, M., Caruso, B., and Killeen, T.J. (2012) Quantifying changes in flooding and habitats in the Tonle Sap Lake (Cambodia) caused by water infrastructure development and climate change in the Mekong Basin. Journal of Environmental Management,