Birthplace of Khmer civilisation at risk of slow death

With the temperatures rising, and floods and droughts worsening due to climate change, Southeast Asia is losing its largest freshwater lake in the eyes of inhabitants of the Mekong Region. Are people defenseless against this development?  

Climate change, a worldwide occurrence, is influencing the timing and size of floods during the wet seasons, which are vital to the Tonle Sap and Mekong basin's health.

“There’s been a string of extremely bad drought years, which lead to lower Mekong River water levels and, thus, lower Tonle Sap lake water levels,” said Abby Seiff, the author of Troubling the Water: A Dying Lake and a Vanishing World in Cambodia

She names also hydropower dams on the Mekong River as the causes of reduced fish migration, as well as rapid population growth, affecting the fisheries.  

A fisherwoman cleans some of the fish she has pulled out of Tonle Sap in Cambodia. Image: Wikimedia Commons

During the June-October monsoon season, the Mekong River floods and reverses the flow of the Tonle Sap, restocking the lake, however, this natural cycle has recently been slowed, indicating that the Mekong is in crisis.

The land-use change and forestry sector accounts for about half of Cambodia's total greenhouse gas emissions (GHG), with deforestation and forest degradation accounting for nearly all GHG emissions. Agriculture was the second-largest emitter, trailed by energy, industrial processes, and waste sectors.

Cambodia, being a developing country, is still tackling poverty, and many people take advantage of all available resources around to improve their livelihoods. Is there any chance to reverse this trend? 


Cambodia’s Tonle Sap, commonly translated as “Great Lake”, is relatively young, having been formed about 6,000 years ago.

Located north of Cambodia’s capital, Phnom Pen, at the end of the wet season, Tonle Sap constitutes the largest freshwater lake in Southeast Asia, although, in the dry season, it shrinks to one-sixth of its might. 

It almost completely connects Phnom Penh to Angkor Wat, the largest religious monument in the world, providing water for half of Cambodia's crops and producing fish that provides half of the country's population's protein. Additionally, it is one of the most crucial transportation hubs in the nation.

Designated as a Biosphere Reserve by UNESCO in 1997 due to its high biodiversity, Tonle Sap and its surrounding ecosystems are, however, increasingly threatened by deforestation, infrastructure expansion, and climate change. A number of activists and environmentalists appeal for the right policies. So far, the government’s actions have brought limited results. 

“I have seen officials taking care of some of the problems,” says Long Kunthea, a Cambodian activist previously jailed by the Hun Sen regime. “Fishing crimes and agricultural cultivation ban have been handled after an order from the president. Trees were planted in some locations”. 

Activist Long Kunthea.

“It’s a good thing,” she adds, “but the authorities should have been protecting the Tonle Sap Lake from the moment the problems occurred, not waiting for the instructions from above”. 

Cambodian media reported that officials undertook an operation to enforce anti-illegal fishing measures and cracked down on a large-scale illegal fishing enterprise. According to the reports, 4,326 persons were reprimanded for gathering freshwater clams or casting nets within the conservation area, proving the big scale of the problem.

“The government should be more active in protecting the resources,” comments Long Kunthea, “on the other hand, it must take legal action against individuals who cut down flood forests, or occupied the land”. 

Having faced months-long imprisonment for being vocal against environmental destruction and corruption, she has, however, little delusion about the enforcement of the law. “We, the activists, are being arbitrarily arrested, while those who destroy natural resources get acquitted”. 

“Violators must be held accountable, no matter who they are,” Long Kunthea adds. “Even if more working groups are created by the government, nothing can be solved without proper and strict law enforcement.”


Tonle Sap was to the Khmers what the Nile was to the Egyptians: a source of prosperity that freed the labour to build vast monuments and foster civilisation.

The Khmer Empire’s power was always based on the lake’s wealth. Many harvests per year and an abundance of fish aided in the maintenance of the royalty and its administration, as well as the financing of the architectural dreams of the royalty. Also, floating villages on stilts that arose during these ancient times and served as transportation links to the Mekong River can still be found around the lake, manifesting a clear connection between the past and present. 

The religious complex of Angkor Wat was initially built as a Hindu temple for the Khmer Empire and used the channels of Tonle Sap to transport stones. The entire city of Angkor occupied a space much larger than modern-day Paris and used a quantity of stone far more than all the Egyptian pyramids put together.

Stilt houses surrounding parts of Tonle Sap. Image: Wikimedia Commons.

Today the town of Siem Reap hosts this site, attracting millions of visitors per annum. 

With Angkor Wat remaining deeply ingrained in the people’s identity, a possible demise of the lake could change the face of the country forever.  

Demographic estimates show that today 1.5 million people live around the lake, out of a total population of 15.5 million Cambodians, the descendants of the Khmer civilisation. Cambodia also hosts people of Chinese and Vietnamese origin.

Nonetheless, despite its abundance of resources in the past, the Great Lake is now at the center of economic and ecological conflicts.


The inhabitants of the area adjacent to the Tonle Sap can be its guardians, saving the resources for future generations. Some, however, are pressed to exploit it for short-term economic gain, proving a need for broad cooperation between the environmentalists, authorities, and fishermen. 

One of the positive initiatives that have been recently conducted aims to restore flooded gallery forests in the provinces bordering the lake. Mimosa pigra — colloquially known as "giant's thorn" — is an invasive shrub that threatens the fish population that has previously infested the deforested area. 

The invasive shrub Mimosa pigra is threatening the environment around Tonle Sap. Image: Wikimedia Commons.

However, Conservation International, a global environmental nonprofit seeks to restore 219,980 trees across 1,260 acres in collaboration with local community fisheries, while also sustainably maintaining the fishing industry.

The project shows that building resilience to external threats is possible. Community members patrol for illegal activity and help with natural regeneration in locations where fishers cut down trees. 

The area of the lake is vast, therefore more concerted actions on a big scale are needed. The site has also potential for carbon financing which could benefit fishing communities in the future. 

As Richard Rogers, an architect and environmental campaigner once said, “The only way forward, if we are going to improve the quality of the environment, is to get everybody involved.”

Banner image: Mateus Bragança de Carvalho on Unsplash  

- Asia Media Centre