Nationwide Route 52 in Cambodia ends in Chnok Tru on the southern part of end of Tonle Sap Lake. The village is a major transfer point for fish and veggies. On a typical day, boats crowd the top and people carry huge plastic baskets ashore.
During the dry season, a concrete pole on the side of the road gives a concept of how different the location looks just a few months later during the rainy season. At about four metres (13 feet), the pole’s colour pales, indicating how high the water can rise.
A lot of that water concerns Tonle Sap Lake through the Tonle Systems applications and products River, which requires water from the Mekong River in Phnom Penh during the yearly rainfalls. The opposite happens in the dry period when the Tonle Systems applications and products River empties the namesake lake plus carries water returning to the Mekong.
The result is that every wet season, Tonle Sap Lake grows five to six moments larger to fifteen, 000 square kms (5, 791 square miles), with its duration almost doubling in order to 220 (136 miles) and its depth boosting from about one metre (3 feet) to more than nine metres (29 feet).
On satellite pictures, this cycle seems like a beating water heart connected to the Mekong as its main artery. The heart has been defeating for thousands of years with a frequency that allowed the folks to adapt to the particular floods by living in houses on stilts or floating.
But climate change plus dams in the Mekong and its tributaries are usually increasingly threatening Tonle Sap Lake’s annual expansion and seafood catch. The increasing number of dams in the Mekong and tributaries upstream of the river dampen the ton cycle by keeping back water during the rainy season.
For your people living on or near the drinking water, the regular muddy surges are a blessing, not a threat. They provide fish larvae and nutrients for coastline farm crops and the plants that feed the lake’s developing fish.
“The Mekong needs its ups and downs, plenty of water during the moist season and very little water during the dry season, ” stated Brian Eyler, the Southeast Asia expert at the Stimson Center, a think tank in Washington, M. C. “The entire ecosystem is fine-tined to those highs plus lows. When the surges are really high, these people scrape wood and sediment and bushes and grasses and rotting stuff to the river to lead to this mix of nutrients that produces the particular explosion of seafood and agricultural efficiency. ”
The nutrient-rich floods have turned Tonle Sap into one of the most productive and biodiverse lakes in the world with more than 200 species of fish. The annual angling haul of a minimum of 300, 000 metric tonnes (330, 693 U. S. tons) is about twice as a lot as the freshwater draws of Canada, South america and the United States mixed, Eyler said.
“Cambodia has the many productive fisheries of any country within the Lower Mekong, ” said Zeb Hogan, a fish expert at the University associated with Nevada, Reno, who leads the Miracles of the Mekong study. “The Tonle Systems applications and products system drives most of that. ”
That’s important because Cambodia is one of the world’s most freshwater fish-dependent countries by area and population, said Marc Goichot, the Asian countries and Pacific fresh water lead for the Planet Wildlife Fund, a conservation organisation.
Cambodians get more than half of their animal proteins from fish, consuming about 75 kilograms (165 pounds) for each person annually, which includes three quarters sourced from Tonle Sap Lake. This is lasting, Goichot added, since unlike agriculture, crazy fish do not consume water, land, fertilisers or pesticides.
Potential heart attack
Environment change is at least partly responsible for more and more drier rainy seasons in Cambodia, professionals said. This was specifically serious in 2019, 2020 and 2021 when monsoon rains came several weeks past due and the Mekong carried unusually little drinking water because of drought.
The Mekong’s 10 lowest flow yrs on record considering that 1910 included 2020 as the lowest, 2019 seventh and 2021 ninth lowest.
What’s more, the particular 86 biggest dams built in the Mekong basin by 2016 reduce water flow into the lake every year by 10 in order to 25%, shorten inundation of the lake’s periphery by two weeks, plus shrink the full areas in the wet season by 245 square kilometres (94. 5 square miles), according to a modelling study published in March by Yadu Pokhrel of The state of michigan State University plus colleagues.
That doesn’t account for 6 of the now thirteen hydropower dams for the Mekong mainstream in China and Laos that began working after 2016. With each other, these dams more reduced the Mekong’s already unusually low rainy season drinking water flow, Eyler mentioned, contributing to a reducing of the lake’s rainy season expansion by one month or more within 2019, 2020 and 2021.
Dams also trap a lot of the nutrient-rich sediment needed for fish plus crop growth. China’s 11 Mekong dams alone hold back 60 per cent of the sediment, Eyler estimated.
Climate change adds to the issue by reducing the amount of tropical cyclones normally washing sediment from Vietnam’s mountains in to the river, said geographer Chris Hackney associated with Newcastle University in britain.
Less water and sediment indicate fewer fish larvae and nutrients within Tonle Sap River, which affects fish catch. There is also a good absence or postpone of high water levels that fish need to spawn in the river or migrate to spawning grounds in the upper reaches from the Mekong or tributaries.
“Every year the water keeps getting lower, ” said Tonle Sap River fisherwoman Hay Sreang. “If the water is very low, there is no seafood. We don’t understand how to make a living. I am worried, I don’t know what to undertake in the future. ”
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That future doesn’t look good: Climate researchers predict the beginning plus end of monsoon rains will shift closer together due to climate change, Eyler said.
Dam building on the Mekong proceeds. China is building a twelfth hydropower dam with seven more prepared. Laos is building a third and programs to build seven more, aiming to become the “battery of Southeast Asia” and sell the power from its dams to neighbouring Vietnam, Laos plus Cambodia, Eyler mentioned.
There are numerous additional dams in the Mekong’s tributaries discovered by Eyler and his team using satellite imagery, including many used for irrigation instead of power generation. They will counted 400, mostly in Thailand but additionally in China, Laos and Vietnam; nearly 400 more are under construction or planned, mostly within Laos, he said.
Construction of all the planned dams in the Mekong and its tributaries may eventually leave the particular Mekong’s waters along with only 4% of its nutrient-rich sediment, Eyler warned.
Pokhrel plus colleagues in 2018 calculated the Mekong’s maximum flow reduction needed to bring the lake’s annual expansion to a halt. Theoretically, these people concluded, the terrifying result could be accomplished through just one mega-dam around the Sambor region in Cambodia.
The 2, 600-megawatt, 18-kilometre (11-mile) dam initially planned near Sambor likely wouldn’t were big enough to achieve this. Yet experts warned the particular dam, which has been delayed until 2030, would deal a dying blow to fisheries in Tonle Sap Lake because it would block one of the Mekong basin’s most important migration routes for about 50 fish species.
The dam’s reservoir also could overflow the homes of nearly 20, 1000 people. One of them is Phloak Sareth, who seem to lives with the girl family on Tnaut Island in the Mekong near Sambor and has worried since 2007 that she might have to move because of the dam.
“If we were relocated, we would not be happy, ” the girl said. On the tropical isle, she has enough seafood, fertile soil plus water to irrigate the vegetables even in the dry time of year, which might be unlikely at a new location. “What if we can’t get water or have a shower, especially throughout the dry season? ”
She said the present dams in the Mekong already dampen the particular all-important flood cycle farmers depend on because the water flow have not remained at the same regularity: “The river normally drops in Feb and March plus rises in May and June. But because of the dams, the water floods our crops as early as February and 03. ”
“The problem I worry about most could be the decreasing number of fish, ” she stated, adding that the dams could drive them into extinction.
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While Cambodia doesn’t yet have dams in the Mekong mainstream, tributary dams are far from harmless. In 2018 Cambodia completed its biggest, the 400-megawatt Cheaper Sesan II dam. Standing 75 metre distances (246 feet) tall and stretching 6 kilometres (3. 7 miles), the dam blocks the Sesan and Srepok streams, two of the biggest Mekong tributaries within Cambodia.
The particular dam keeps fish from migrating from the Mekong and Tonle Systems applications and products Lake to their spawning grounds, with severe consequences for seafood yields, according to a good August 2021 report by Individual Rights Watch.
Fish catches upstream declined dramatically following the dam’s launch, leading to lost income of $100 or $200 per month and higher costs for purchases of additional food. A canal built to allow fish migration around the dam often carries little water and is far from a sufficient substitute, according to the report.
The dam’s tank, covering about three hundred square kilometres (116 square miles), overloaded several villages, making about 860 families to move. As payment, they each were offered a few hundred dollars, a small house having a field several kilometres from the river or even $6, 000 to build a house. About eight hundred families accepted.
But about 60 families refused and built new houses on property about a kilometre from the original site, including the family of Fut Kheun, who lost his home and veggie field. “We don’t want to be far away from your ancestors’ graves buried under the flood, ” Kheun said. “The idea for the brand new village is to make it like the old town. ”
But the brand new location lacked thoroughly clean water and educators, preventing children from attending school for years. He said the federal government should use different ways to generate energy than building hydropower plant life.
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The main city and the sand
The famous flow reversal, where the Mekong rises so high during the rainy season that will water flows in to the Tonle Sap Lake instead of out, takes place at the Chaktomuk junction in the capital, Phnom Penh.
In this crucial place, ships can often be observed staying put for hours or days. The particular vessels are exploration sand, according to Hackney, who has counted all of them using satellite symbolism.
On Cambodia’s southernmost, 150-kilometre (93-mile) stretch of the Mekong, which includes Phnom Penh, Hackney counted a daily typical of about 50 ships in 2016; by 2020, the average was 120.
The 2020 figure translates into close to 59 million metric tonnes of sand (about 65 mil U. S. tons) being extracted from your Mekong each year in Cambodia alone, nearly 10 times the 6 million metric tonnes (6. six million U. S i9000. tons) the lake carries annually.
This means the riverbed between Kampong Cham in Cambodia as well as the Mekong River delta in Vietnam is usually sinking by about 10 centimetres (3. 9 inches) per year, Hackney said, adding that will since the 1990s the total may be 1 metre (3. 2 feet) or more.
Because of the reduced riverbed, the Mekong’s rainy season water levels eventually may not be able to rise sufficient to reverse the particular Tonle Sap River. This makes fine sand mining the third major factor, along with environment change and dams, threatening the lake’s annual expansion, Hackney said.
Like climate change and dam building, sand dredging is unlikely to end anytime soon. The sand is used at Phnom Penh’s numerous construction sites or meant for building artificial islands or filling wetlands for construction.
Most of the Tompoun/Cheung Ek wetland in the city’s south, which addresses about 15 sq . kilometres (5. 7 square miles) plus filters about half associated with Phnom Penh’s wastewater, could disappear.
Without the wetland, most of the wastewater would find yourself untreated in the Mekong and Bassac streams and large parts of the city would be from greater risk of flooding during the wet season, a group of Cambodian NGOs warned within a 2020 report. A wastewater treatment flower planned to make on with the wetland’s reduction, the NGOs additional, could only process a 50th from the wastewater entering each day, far from enough.
High agriculture costs
Should weather change, dam construction and sand exploration continue to reduce the nutrient-rich floods and the seafood in the Mekong plus Tonle Sap River, the missing protein would need to be replaced by agriculture.
As opposed to fishing, agriculture demands water: About one, 000 litres (264 gallons) for a kilogram (2. 2 pounds) of soy with least 15, 1000 litres (3, 962 gallons) for a kilogram of beef, based on Goichot.
Agriculture also requires slicing forests, reducing the particular available water. Without having forests, the microclimate often becomes more dry and results in longer drought periods, as well as the soil stores less water, resulting in less groundwater during the dried out season.
Already, Cambodia’s deforestation rate is one of the highest on earth and is accelerating, based on Thomas Dilts, the landscape ecologist at the University of Nevada, Reno, who has analyzed the Kingdom’s deforestation using satellite symbolism.
Dilts and colleagues found that will between 1993 plus 2017, the country lost about one-fifth from the forest. At Tonle Sap Lake, losing was as much as another, mostly in the inundated forests that protection growing fish.
Deforestation, increasing farming and urbanisation have also measurably worsened surface water quality in parts of Tonle Systems applications and products Lake and the Mekong, according to a 2021 study by Dorothy Null of Utah State University and colleagues.
Groundwater is another problem. At the Angkor Wat temple complex within Siem Riep, a 2019 study showed population growth, travel and leisure and construction has already caused the ground generally there to sink as a result of excessive groundwater pumping . Continued pumping could also lead to further accumulation of toxic arsenic.
Seeking solutions
“It’s like ‘death by a thousands of cuts, ” Null said, explaining you will find no easy solutions facing Tonle Systems applications and products Lake and the Mekong.
Using the Lower Sesan II dam blocking seafood migration between the Mekong and the Sesan and Srepok rivers, it is important to avoid constructing dams in Cambodia’s third major Mekong tributary, the Sekong, Null said, mainly because dams there would block the migration routes of at least 64 fish varieties.
Eyler hopes dams might lose their appeal for power production because climate change makes droughts increasingly frequent. The low Sesan II dam’s failure to prevent several power outages throughout the 2019 dry season “sent a signal towards the Cambodian government, ” said Eyler, who also hopes for recognition of the potential of choice energy such as solar energy by 2030.
Eyler hopes Laos will also reconsider building prepared dams. Ecotourism can become a big financial driver there, following a lead of countries such as Costa Rica.
Ecotourism could also make Tonle Sap Lake occupants less dependent on angling, according to Thies Geertz of the German NGO Global Nature Fund (GNF).
GNF works with the Cambodian NGO Fisheries Activity Coalition Team (FACT) to make the Tonle Systems applications and products Lake floating town Phat Sanday more attractive to tourists. The particular initiative includes creating a water treatment vegetable for 1, 500 people, converting organic waste into fertiliser for sale and pressing plastic waste straight into fish storage containers.
The German authorities and the German Wilo Foundation committed four hundred, 000 euros (about $420, 000) towards the project. Geertz hopes the project can eventually pay for itself by income through tourism: “We need this to become a model for sustainable advancement a fishing village, for others to copy it. ”
To guard against overfishing, GNF and FACT also secure the largest fishing sanctuary in the lake, an area of nearly 10 square kms (3. 8 square miles) next to Phat Sanday, where angling is prohibited therefore fish can migrate and grow.
Until recently, fishers often overlooked the ban. They only started staying away from the area once TRUTH and GNF founded a barrier plus regular patrols at the begining of 2020, FACT’s Senglong Youk said.
Initially some fishers complained about the closure, but the catch just outside the reserve retrieved significantly, Geertz stated, from 9 kilos (19. 8 pounds) daily per fisher at the beginning of 2019 to a little more than thirty kilograms (66 pounds) by late 2021.
“The success is certainly outstanding, ” Geertz said.
But if the nutrient-rich floods stop coming, none of that will issue. Without them, even the best-guarded sanctuaries will not keep fish from eventually disappearing.
Videos, images plus graphics by Andreas von Bubnoff to get Southeast Asia World.
Andreas von Bubnoff is a freelance reporter and professor of science communication based in Germany who from time to time teaches journalism in the Royal University associated with Phnom Penh.
This short article is part of the “Hidden sources of clean water” project by the German journalism collective RiffReporter. The project had been funded by the Western european Journalism Centre through the European Development Journalism Grants programme with support from the Bill and Melinda Entrance Foundation.