As the largest freshwater lake in Southeast Asia, Tonle Sap, located in the heart of Cambodia, is a highly productive and volatile system. Currently, 1.2 to 1.5 million people move with the lake’s temporal change each year, but live in poor and unhealthy conditions. The goal of the project is aimed at how to interpret the native landscape and nature of the lake while improving the overall quality of life for the communities that call it home. Three main strategies are designed to improve the ecosystem, health, and economy: waterless toilets and an anaerobic digester, fabricated mangrove reef balls, and a constructed wetland and silvofishery. Each implemented system would create a new network that would positively impact the surrounding human and environmental communities. With the success of one primary site, each technology could be adapted and phased into the other major community sites around the Lake’s perimeter and potentially improve the quality of life for over 10% of Cambodia’s population.
Within the Kingdom of Cambodia is the largest freshwater lake in Southeast Asia, Tonle Sap. Imagery of the lake and its usage dates back to the Khmer Empire over 1200 years ago, and the Lake is still heavily used today. Currently, 1.2 to 1.5 million people live on or around the lake which accounts for just over 10% of the Kingdom’s total population. The lake can swell four to six times its size during the wet season which creates a fluctuating and volatile ecological system that is also an integral part to the country’s economy. The project aimed to examine how landscape architects could interpret and analyze a major regional system and implement certain strategies that would improve both the regional ecosystem, quality of life for the communities, and maintain the existing cultural integrity of the area.
Tonle Sap Lake and the surrounding floodplain are highly productive regions for the country’s agricultural system. 300,000 to 400,000 tons of wild-caught fish are harvested each year from the lake and the floodplain farms large amounts of rice, and livestock. However, the population that lives around the lake that migrate with the lake’s fluctuating size live in poor and unhealthy housing that is contributing to the degradation of the surrounding ecosystem. 54% of the Lake’s population practices open defecation and only 1 in 77 children will live past the age of five due to poor living conditions. This poverty has contributed to a devastating cycle of raw untreated waste being dumped into the water, which the wild fish then eat, bioaccumulating diseases and contaminants, which when caught by the communities further magnifies the effects of the major diseases that plague the area. Tonle Sap has also experienced large amounts of mangrove loss which is increasing the damage of flooding while also reducing fish and bird habitats for the region.
Currently, the communities are suffering from dire poverty. The average household is in debt over $780 USD and bringing in only $1000 USD each year. 40% of children on the lake are chronically malnourished and the common diet of the area is made up of 74% fish protein which comes primarily from contaminated wild caught fish. Utilizing simple, yet effective interventions, new forms of economic generators would help reduce the region’s debt while also improving their overall health and the surrounding environment.
The project calls for the implementation of three key strategies that would tackle these main issues that are currently happening throughout the region. Each strategy serves multiple functions that improve the overall environment and quality of life. The site selection for these strategies is the ferry terminal and Chong Khneas community that is a 15-minute drive south of Siem Reap. Since Siem Reap is a major national city and tourism hub, it will serve as a major foundation due to the existing infrastructure the area has.
To combat the vicious diseases affecting many of these people, waterless toilets would be a first step in reduction. The toilets operate as one simple unit comprised of a body, seat, bowl, and removable storage compartment. Biodegradable liners are attached to the bowl and when waste is deposited into the bags, they self-release and close on themselves, preventing anyone from interacting with waste. It is then stored in the compartment and can be removed when the household decides to discard it. However, to prevent the waste from being dumped into the water, the construction of an anaerobic digester would serve to manage the issue. The digester breaks down the waste into two major products: biofertilizer and biogas. Biofertilizer could be sold to surrounding farmers to reduce demand for synthetic methods while maintaining crop yields, and the biogas could be sold back to the city electricity grid, or used to fuel the floating homes through cooking and heating gas. As an incentive, the anaerobic digester’s operators could pay the families for their waste which would add a new and sustainable economic opportunity that every member of the community could contribute to. As more waste is removed from the water, wild fish catch contaminants would be reduced and disease rates would decrease.
Fabricated Mangrove Reef Balls:
Due to increased loss of mangroves across the Lake, habitat loss and flood damage rise each year. To combat this problem, constructed mangrove reef balls would restore lost areas of mangrove cover. The reef balls would be fabricated using the existing lacustrine alluvial soil that is rich in clay. Mangrove saplings would be planted in the ball and over time, the roots would branch out through the designed holes and the ball would decompose back into the native soil profile. The mangroves would provide habitat for wild fish and nesting birds while also sequestering carbon. Throughout the year, both men and women could work to create and plant these reef balls which would provide another source of income for the area that does not require major educational training.
Constructed Wetland and Silvofishery:
In order to improve the food quality and, in turn, the overall health of the community the existing water must be cleaned and treated so that it could then be used for aquacultural purposes. Water that flows from the ferry terminal into the lake is heavily turbid. Constructing a wetland that utilizes native wetland plants and mangroves would settle the suspended sediment while also capturing and breaking down contaminants through phytoremediation. As the water moves throughout the wetland, it is churned which increased the dissolved oxygen levels necessary to farm catfish. When the treated water enters the silvofishery, it flows through narrow channels that are planted with mangroves on either side. These mangroves would provide shade for the catfish, algae and leaf litter for a natural food source, and roots for habitat and spawning areas. When the farmers choose to harvest the catfish, they would be able to shut each channel off through a weir system that would gradually bring the fish into the harvesting pond. Then, either through net catching or industrial methods, the concentrated fish could be harvested and sent off to markets to be sold. This clean food source would supplement the existing diet with a new source of healthier fish protein which would provide a new and renewable calorie and protein source. The water used by the catfish would then travel through a secondary constructed wetland that would then begin to treat and clean the water again before it reenters the water system.
Each of these interventions has the potential to be adapted and phased to other communities on or around the lake. They would provide new streams of economic revenue to multiple sectors of the country, while also preserving the existing natural and social culture of the Tonle Sap Lake. As such a volatile geologic feature that affects millions, landscape architects could plan and implement future uses that protect, restore, and champion the native ecologies while also improving the health, safety, and welfare of citizens in the global community.