Freshwater health index assessment of the Tonle Sap basin
Nicholas J. Souter, Kashif Shaad, Sor Ratha, Derek Vollmer
Cambodian Journal of Natural History, 2023, 34-61
July 05, 2023
The Tonle Sap Lake and River basin cover almost half of Cambodia’s land surface, contain one of the world’s largest inland fisheries and are rich in biodiversity. While the Tonle Sap Lake and its relationship to the Mekong River is well studied, until now the freshwater health of the basin has been overlooked. We used a freshwater health index to diagnose the basin’s condition as of December 2021. Ecosystem vitality and ecosystem services scored 41 and 75, respectively, out of a possible 100, while governance and stakeholders scored 58. Consistent with freshwater health assessments in other parts of the Mekong, the Tonle Sap basin provides valuable ecosystem services. But components of its underpinning biophysical system are degraded. The basin’s highly fragmented river network and high numbers of threatened species (particularly fish) threaten the future of the lake’s vital fishery, which received a moderate score of 60. Stakeholders rated the water governance system and degree of stakeholder engagement as moderate. While the degree of conflict was low, the development of irrigation infrastructure will likely impact flows to the lake, thus affecting the fishery. That stakeholders were divided over the importance placed on the provision of a reliable water supply versus the fishery, indicates a potential future point of conflict. We identified data deficiencies, revealed important social dynamics, provided stakeholders with a basin wide perspective, and highlighted the importance of a healthy environment for the future of Cambodia’s most important natural resource system.
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Souter, N.J., Shaad, K., Sor R. & Vollmer, D. (2023) Freshwater health index assessment of the Tonle Sap basin. Cambodian Journal of Natural History, 2023, 34–61.
