We depart Can Tho, the bustling heart of Vietnam's Mekong River Delta, before sunrise and head south to a fish farm in the coastal province of Ca Mau. I heard that this farm is a demonstration of how farmers in the delta protect scarce fresh water during the hot dry season.
A few hours' drive takes you to the country's aquaculture hub, known as the „Rice Bowl.“ The most impressive thing for visitors is that almost all of the land here is either cultivated or built on. The house is next to a shrimp farm, where workers are loading melaleuca tree trunks onto trucks. Narrow roads parallel the crossings of canals built for irrigation and transportation.
But all is far from smooth sailing in this seemingly agricultural paradise. Most of the waterways are dry, with exposed muddy bottoms and cracks. This is not unusual during the dry season, but the cracks have become more visible over the years, emblematic of the deepening cracks that are stressing the region of 20 million people.
Primarily in China and Laos, sand mining in rivers and the interception of important sediments by upstream dams are depleting the very components of the delta region, leading to rapid subsidence. Land subsidence caused thousands of roads and buildings to buckle and collapse. And as climate change intensifies, rising sea levels and reduced freshwater flows will push more seawater onto land, increasing risks to agriculture that relies on freshwater, such as rice cultivation.
How do you implement nature-based solutions in the Mekong Delta, where 2% of the land remains untouched?
The urgency to save the Mekong Delta brought together international organizations, development banks, the Vietnamese government, local organizations, academics, and farmers. The delta region currently attracts more funding for environmental initiatives than any other region in Southeast Asia. Importantly, there is broad consensus on what should be done. It's about leveraging so-called nature-based solutions (NBS in conservation parlance), which harness natural processes to promote ecosystem health.
„We have to stop fighting nature,“ says Nguyen Huu Tien, a Can Tho-based natural resources expert and freelance consultant.
Nature-based solutions are commonly described as means of protecting, restoring, or managing natural ecosystems. Typical NBS initiatives include reforestation projects to restore degraded landscapes and the establishment of protected areas to preserve natural conditions.
But how do you implement nature-based solutions in regions like the Mekong Delta, where only 2% of the land remains untouched? Where huge embankments are built to divert natural flood waters. And where have entire ecosystems been completely modified for agricultural use?
Originating in the Tibetan Highlands, the Mekong River traverses six countries before splitting into two rivers below Cambodia's capital, Phnom Penh. Both of these tributaries reach Vietnam and then spread into the delta region and the South China Sea. Colonial geographers in the 1800s described the delta region as a harsh place where malaria was endemic.
In the 1930s, the French began building levees and polders to channel fresh water into areas where rice could be grown during the dry season. Although rice can tolerate short-term water shortages, it generally requires stored water for a significant portion of its life cycle, especially during critical growth stages.
But it wasn't until the 1980s and 1990s that Vietnam, desperate to grow its economy through rice production, developed an extensive network of irrigation canals. To support the growth of three rice crops per year, an extensive ring dike system was established to store fresh water and protect the cultivated land from flooding.
This „Rice First“ policy saved the war-torn country from starvation and transformed it into a major rice exporter. However, the re-engineering of the delta has also brought about dramatic hydrological changes. High levees in the upper delta protected crops, but water levels downstream rose during peak floods, culminating in devastating floods that killed more than 450 people across the delta in 2000. .
The problem is even worse upstream, where hydroelectric dams built on the main Mekong River are reducing the amount of sediment that would have been flushed downstream to feed farms along the way and help restore and rebuild the delta. flow was obstructed.
The Vietnamese government has come to understand that its intensified rice cultivation policy is destroying the environment and limiting economic opportunities. It began advocating agricultural diversification policies aimed at shifting production from rice monoculture to more diverse agricultural approaches, including aquaculture, fruit trees, and horticulture. In 2017, lawmakers passed a law known as Resolution 120 that reflects the country's commitment to sustainably manage and conserve natural resources.
Many international projects encourage the revival of agricultural practices that use natural flooding.
„The Vietnamese government recognized the importance of living in harmony with nature,“ says Van Pham Dang Tri, director of the Climate Change Institute at Can Tho University.
The farm we are visiting is located in Phu Tan district near the coast and is owned by Thiu Hoang Pho, who grew up here and works for the Government Science and Technology Agency. Like other local farmers, Pho grows shrimp in a pond connected to a saltwater canal. But the Four also built freshwater ponds that blocked out the surrounding salt water. He collects fresh water during the rainy season and uses it to grow freshwater fish during the dry season. There are various fruit trees growing around the pond, including coconut, jackfruit, banana, mango, and durian.
Mr. Pho explains this while holding a few plums as he descends from a ladder. „This is a multi-value farming model that can be replicated at home level without expensive infrastructure.“ Soon, he plans to start growing water hyacinth, which can be used for everything from animal feed to crafts.
Many international projects encourage the revival of agricultural practices that take advantage of natural flooding, such as lotus cultivation and the combination of floating rice grown under flooded conditions and fish farming. Such a method has proven to be much more profitable than monoculture of rice. The World Bank is supporting a major effort in the upper delta to rehabilitate levees to restore natural flooding regimes to agriculture.
Thiu Hoang Pho, who works at a freshwater pond in Phu Tan, collects rainwater to raise fish.
Stefan Lovgren
„We often think of floods as a bad thing because it's much easier to measure the damage than the amount,“ said Mark Goichaud, Asia and Pacific freshwater director at the World Wildlife Fund. says. The fund supports flood agriculture projects that emphasize community decision-making. “But flooding has many benefits, from washing the land of pollutants to bringing nutrients and recharging aquifers.”
Experts say simple adjustments to water management infrastructure, such as opening flood gates within river and canal networks, can mimic natural flooding conditions. Rather than keeping gates closed for saline water protection, opening these gates to simulate natural flood cycles creates aquatic habits, for example, allowing fish to migrate from river channels to floodplains. It helps them move and feed and breed there.
“Currently, fish are almost never found in these intensive rice-growing areas,” says Andrew Wyatt, vice-representative for the Lower Mekong region at the International Union for Conservation of Nature, which developed the global standard for nature-based solutions. . It must benefit both humans and biodiversity.
Some experts say the Mekong Delta is a case study in how nature-based solutions can be used to mimic natural processes. „Restoring entire socio-environmental systems like the Mekong Delta that are fundamentally threatened by human activities requires rethinking nature-based solutions beyond just local vegetation restoration.“ says Rafael Schmidt, who has studied dams and Mekong sediment issues for many years. He is also the lead scientist at Stanford University's Natural Capital Project.
Although there is no obvious nature-based solution to addressing sand and sediment loss, it is possible to improve practices.
Although the Vietnamese government has voiced support for environmental policies, some officials still cling to traditional rice-based agricultural approaches in the delta, according to some sources. Aimed at stopping the spread of seawater, projects like the $129 million Kairon-Kaibe double sluice gate, completed in 2021, are seen by their backers as a focus on economics rather than a commitment to sustainable practices. It has drawn criticism from critics who say it is motivated by public interest. .
Across the delta, roads and other infrastructure are crumbling and land is sinking up to four times faster than sea levels. Research shows that upstream dams capture up to 50 percent of the sediment in the Mekong River basin that would otherwise reach the delta and be replenished. Mining for sand used in construction and manufacturing removes five to nine times more sand per year than is deposited in the delta.
There are no obvious nature-based solutions to address sand and sediment loss. But experts say practices can be improved. For example, dams can be built in locations that do not cause as much damage, and sand can be extracted from locations that are less important to land stability.
Improving sand and sediment flow is also essential to restoring mangrove forests, which play a key role in mitigating coastal erosion and act as natural barriers against storm surges. Mangrove restoration is considered a more traditional nature-based solution rather than a modified process to restore natural conditions.
However, in many places, Vietnam's mangrove forests were destroyed by Agent Orange spraying during the American war. Elsewhere in the delta, offshore rock walls built to protect shorelines from large waves are changing water and coastal dynamics, causing mangrove forests to be washed away.
Several mangrove restoration projects have begun in the delta, but efforts are complicated by less sediment reaching the ocean. „Mangroves need to capture enough sediment to build a root system,“ Schmidt says. “Planting mangrove trees where there is no sediment is a waste of time.”
Back in Can Tho, Tien, a consultant, said the era of engineering and architecture that ignored nature is over. „Before we were so intent on conquering nature. We never thought for a second how it worked,“ he says. „At least now we're starting to respect natural law. We're moving in the right direction.“