Wetland project tests blueprint for Yangtze protection

Editor's note: As protection of the planet's flora, fauna and resources becomes increasingly important, China Daily is publishing a series of stories to illustrate the country's commitment to safeguarding the natural world.

On the shores of Anhui province's Chaohu Lake, China's fifth-largest freshwater lake, reeds bend in the wind across restored wetlands, while egrets pick their way through shallows that, just a decade ago, reeked of fertilizer runoff.

This is Shibalianwei wetland, a 27.6-square-kilometer expanse in Hefei's Feidong county that has undergone one of the most ambitious ecological reversals in the Yangtze River Basin. Once carved into nearly 13 sq km of intensive fish ponds and rice paddies, it has been transformed into China's first ecological wetland designed to serve simultaneously as a flood storage basin, a water purification system and a wildlife sanctuary.

As endangered Oriental storks were spotted raising their chicks for the first time ever in the wetland in May this year, the 2-billion-yuan ($294.8 million) project stands as a critical blueprint for the country's broader Yangtze River Protection Strategy, testing whether heavy hydraulic engineering can coexist with regional ecological and economic development.

The name Shibalianwei, meaning 18 linked polders, tells a tug-of-war story between humans and nature. For centuries, the mudflat was laced with 18 earthen embankments, each one a small barrier against water that wanted to spread.

However, as grain and aquaculture demand surged in the 1980s, local populations pushed the land too far. They drained marshes, dug ponds and doused the soil with agricultural chemicals. By the early 2000s, the ecological consequences were stark, with notorious algae blooms, collapsing fish stocks and degraded wetland functions.

"Back then, the water smelt bad, and the fish grew smaller every year," said Yao Jiqiang, 70, a former fisherman who spent around two decades raising fish in the waters.

The turning point came in 2016, when the comprehensive treatment of Chaohu was elevated to a national priority under the Yangtze River Protection Strategy — a shift from fragmented local efforts to a holistic, basin-wide campaign.

Song Xiaofei, director of the bureau of natural resources and planning in Feidong county, said Shibalianwei is envisioned as a multifunctional shield for the city. "This project involves a flood storage basin to absorb excess runoff during peak floods, a natural bio-filter to cleanse nutrients from the Nanfei River before they reach the lake, and a restored habitat for migratory birds along the East Asian–Australasian Flyway," he said.

To make room for the new ecosystem, the physical and social landscape had to be radically restructured. In 2018, in a coordinated push to reclaim the wetland, 12,000 residents from 56 villages were resettled into modern housing. Operating rights for 350 hectares of fish ponds were reclaimed from 377 aquaculture households, and all remaining intensive shoreline aquaculture was fully phased out.

With the land cleared, bulldozers breached the embankments that had choked the waterways for half a century, allowing fresh water to surge back into the parched channels.

The dredging of 533 fish ponds provided millions of cubic meters of sediment, which was used to construct 33 elevated filtration islands within the wetland. Rather than hauling the muck away at great expense, engineers first drove piles to stabilize the soft sludge, then planted metasequoia and Chinese tallow directly into the newly formed land. These trees anchor the soil with their roots, gradually absorbing nitrogen and phosphorus from the water.

They also planted more than 12,000 fruit-bearing trees — peach, persimmon and apricot — to feed migratory birds. In total, 410 hectares of habitats were reconstructed, ranging from shallow marshes and deep-water zones to swamp forests, providing shelter for returning wildlife.

Torrential rains in July 2020 brought the Yangtze basin its worst flooding in decades, threatening Hefei's urban defenses. In response, the construction of smart inlet and outlet sluice gates was fast-tracked later that year.

Designed to handle 450 cubic meters per second, the completed wetland now acts as a giant sponge, capable of absorbing more than 100 million cubic meters of floodwater within three days.

At full operation, it is expected to lower Chaohu Lake's water level by approximately 14 centimeters and the urban river level by 20 cm.

"Shibalianwei has a total flood storage capacity of 109 million cubic meters. It can be filled in three days and drained in seven, transforming a destructive disaster into a controlled hydraulic operation," said Li Jiazheng, general manager of Hefei Shibalianwei Ecological Construction Management Co, the State-owned company responsible for the wetland's restoration, conservation and management.

Li added that this operational flexibility, bolstered by smart sluice stations and early-warning surveillance cameras, allows it to handle a wide range of flood scenarios on the Yangtze River. This technological integration transforms flood storage from a passive endurance test into an active, precision-controlled operation.

That dual mandate — flood retention and ecological restoration — was underscored by President Xi Jinping during his 2020 visit to the area, affirming the wetland's role not just as a hydraulic buffer but as a living filter for the lake.

Today, acting as the "kidney" of Chaohu, the wetland filters around 600,000 cubic meters of water daily from the Nanfei River. Monitoring data show that ammonia nitrogen and phosphorus concentrations have been cut by over 30 percent compared with the inflow. The water has jumped from inferior Class V — the lowest grade for surface water, essentially polluted and unusable — to Class III, which is clean enough to support aquatic life and safe for indirect human use.

Complementary industry

In the retained paddy fields surrounding the restored wetland, rice is grown together with Chinese soft-shelled turtle in the same plots — a traditional Chinese practice known as integrated farming.

The turtles feed on weeds and insects, while their droppings naturally fertilize the rice. In return, the standing crop provides shade and habitat. No chemical fertilizers or pesticides are applied, resulting in both premium eco-labeled rice and high-value aquatic products under the "Shibalianwei" brand.

The same fields take on a second role after the autumn harvest. Across the 192 hectares of farmland within the wetland, water levels are raised plot by plot to between 30 and 50 cm, turning the paddies into shallow foraging grounds for endangered species such as the Siberian crane, Oriental white stork and Baer's pochard.

Leftover rice stalks and scattered grains — together with aquatic plants, lotus roots and other natural vegetation — become an important food source for wintering birds, allowing the wetland to double as a seasonal sanctuary without sacrificing a single harvest.

The restoration fundamentally transformed the relationship between humans and nature.

When asked to stop fishing in 2020, Yao Jiqiang felt adrift. Despite his uncertainty, he supported the restoration. "I didn't want future generations to look at a dead lake," he said.

After surrendering his boat and nets, Yao became a wetland ranger, spending his days mowing the marsh grass before it dies back and rots into the water, monitoring birds and ensuring no one disturbs the wetland. Without the constant fish waste and chemical fertilizers of the past, the water has cleared dramatically.

"I used to hate birds for eating my fish. Now, I keep the water clean for them," Yao added.

Mei Dangfu, 75, was among the first of the locals to be relocated. Initially unsettled by the disruption, he has since embraced his new life in a modern 90-square-meter apartment.

The transition was smoothed by an ecological employment priority for locals. Mei landed a security post at the wetland. "I'm happy to see that the number of overwintering swans has increased in recent years," Mei said.

Monitoring data confirm these observations. Since restoration began, plant species have risen from 331 to 412, fish from 36 to 64, and birds from 63 to 232.

Winter bird-watching, spring flower viewing and science education tours draw tens of thousands of visitors annually. Combined with ecotourism and specialty aquaculture, the wetland generates over 20 million yuan in annual output value and creates more than 100 local jobs.

limenghan@chinadaily.com.cn