“The water of the Erhai Lake is clear, and the Ottelia acuminata which had disappeared for years has come back!” said Jia Feng, director of the Publicity and Education Center of the Ministry of Ecology and Environment, while attending the 2021 Global Ecological Civilization Construction (Erhai) Forum on October 9. Ottelia acuminata, an aquatic plant species endemic to China, is known as a yardstick of water quality, because it needs high-quality water to thrive.
Five years ago, when Jia visited the Erhai Lake, located in Dali Bai Autonomous Prefecture, southwest China’s Yunnan Province, the water was polluted by blooming blue-green algae. This time, the unique plant with delicate blossoms Ottelia acuminata has returned to the water. “As a rare species, Ottelia acuminata has been listed in the International Union for Conservation of Nature (IUCN)’s Red List of Threatened Species and is also regarded as an environmental indicator plant for gauging the eutrophication of lakes,” said Jia.
A waterbird flying around the Baofeng Wetland in Kunming, Yunnan Province. Zhang Wei
Applicable Erhai Model
Erhai Lake, which has nurtured generations of Dali people with its rich products and clean water resources, became overly enriched with nutrients since the 1990s, resulting in excessive growth of algae and plankton, and the deterioration of water quality. The restoration of the water quality has caught the attention of local people, as well as the government, who has listed it as a national major science and technology project for water pollution control and treatment.
“Actually, most of the pollutant sources come from human activity,” said Kong Hainan, chair professor at the School of Environmental Science and Engineering of Shanghai Jiaotong University, and the director of the Erhai Project. He has long been engaged in the lake pollution control and treatment project. “It is my lifelong mission to protect the water,” he said.
Over the past 20 years, Kong spent an average of more than 200 days a year at the research station on the bank of the Erhai Lake. To protect the lake, both the government and its people have pooled their efforts to change the local development model and production methods. For example, the Dali people have abandoned their tradition of planting garlic because it uses large amounts of pesticides and fertilizers, which contribute to water pollution. After years of hard work, the water has changed from murky to clean, reaching the national water quality standards of Grade II and Grade III for three consecutive years. China grades its water quality in six levels, from Grade I to Grade VI, with Grade VI being the most polluted. “In 2006, when the national project was launched in Dali, Ottelia acuminata was listed as a rare and endangered plant, but it had long been extinct in the Erhai Lake. Today, its reappearance is a testimony to our efforts, and also the best interpretation on the ecological civilization of China,” said Kong.
In the stores of Shanghai, 300 grams of Ottelia acuminata sell for about RMB 20. It means that one hectare of Ottelia acuminata can earn RMB 105,000. “The water quality and the ecological environment have improved, but not at the cost of the decline of local people’s incomes. Instead, it has formed a sustainable aquatic ecological environment in which people live in harmony with nature,” said Kong.
He has participated in numerous projects to treat rivers, lakes, and reservoirs such as the Taihu Lake, Chaohu Lake, West Lake, Erhai Lake, Dianchi Lake, Three Gorges of the Yangtze River, and Suzhou Creek. He said that 95 percent of lakes across the nation were challenged with the same water pollution as the Erhai Lake, which means that the lessons of Erhai can provide a reference for the governance of other lakes, and the Erhai model that has been explored over the years is also applicable in many developing countries.
“China’s Erhai model is sure to benefit the world. I hope that this government-led model, which combines the rule of law and science and tech support, with the participation of innovative enterprises and local people, can be applicable to more lakes that have been plagued by water pollution,” said Kong.
Ottelia acuminata, the unique plant with delicate blossoms, has returned to the Erhai Lake in Dali Bai Autonomous Prefecture, Yunnan Province. Zhang Wei
A Treasure House of Biodiversity
Yunnan is known as a treasure house of biodiversity, both in China and around the world. The Baofeng Wetland on the east bank of Dianchi Lake in Kunming, capital city of Yunnan, covers an area of 108.92 hectares, including 19.07 hectares of the biodiversity display area. Yang Junxing, a researcher at the Kunming Institute of Zoology of Chinese Academy of Sciences, said that the return of indigenous organisms such as the rare species of Ottelia acuminata and golden-line barbels swirl to Dianchi Lake, can be seen as a milestone event in biodiversity conservation.
After years of research, Yang and his team have discovered the ecological restoration model of “flower-fish-snail-bird” for plateau lakes and wetlands, which involves the aquatic plant Ottelia acuminata, the native golden-line barbels swirl in Dianchi Lake, unique aquatic benthic organisms of plateau lakes, and black-necked cranes. “This model can restore the lake ecological environment and also protect the indigenous species, which means alleviating the environmental pollution without breaking the balance of the lake ecosystem,” said Yang.
In the key plant display area of the Baofeng Wetland, 12 varieties of plant communities are lined up in an orderly manner, with different shapes and colors. “A total of 101 species of endemic plants in central Yunnan have settled here, fully demonstrating the genetic and ecological diversity of Yunnan’s plants,” said Yang.
Strolling in the wetland park, visitors can hear birds sing and see the amazing dance of egrets and moorhens. Passing through the scenic pedestrian area, visitors are led to the Haifeng Bridge beside the Dianchi Lake, a bird-watching pavilion hidden among the groves which is perfectly integrated with nature. A one-way direction load to the pavilion is used to minimize interference of the birds. Large-sized arbors planted around the lake have become a natural shelter.
Fish can enjoy a leisure life in the wetland too, as dead branches are used to control water flow, and rocks are built into nests – all of which have increased the complexity of the water system and the diversity of hydraulic conditions. Moreover, aquatic plants are planted to create a good habitat for the fish. At the 1.5-meter-high glass submerged corridor, visitors can observe the indigenous and rare species of fish in the Dianchi Lake through the glass.
“This is a microcosm of the water ecology of Dianchi,” said Yang. The return of these indigenous species will enrich its biodiversity and form a more balanced ecosystem, which is an important indicator of the continued improvement of the water ecology.
Professor Kong Hainan (right) introducing China’s experience in the eco-preservation and water management of the Erhai Lake. Zhou Lin
Protecting Nature, Protecting Ourselves
Kunming, known as “the City of Perpetual Spring,” is also famous for its plateau lakes and abundant water. The Dianchi Lake, located in the southwest part of Kunming, has a reputation as “A Pearl on the Plateau.”
To the northwest of the city, clear spring water rushes down from the Changchong Mountain, joins urban rivers, and then flows into the Dianchi Lake. To ensure that the water flows through the city without being polluted, Kunming people adopted the sustainable method of “governing the river water before it flows into the lake.” Concepts of biodiversity protection, a sponge city, and people-friendly environment have been combined and put into restoring the ecological function of the river. And the method works well in conserving water sources and improving water quality, thus forming a benign interactive aquatic ecosystem.
“If you walk in the city nowadays, the roads are not slippery on rainy days; and even in heavy rains, people never need to wade through waterlogged roads. That is because we built the urban wetlands,” said Zhang Shihua, director of the Water Supplies Bureau in Kunming’s Wuhua District. He further explained that, due to the rapid development of urban areas, more hard surfaced roads have been built over the past few years. And to save space, most rivers have been transformed into underground rivers or hidden ditches. So when there was heavy rainfall in summer, water from the mountainous areas would flow into and flood the city accumulating on cement roads as there was nowhere to go.
However, the concept of a sponge city inspired the local government. Now the underground rivers have been changed into ecological reservoirs. And the newly built urban green spaces and ecological corridors have been specially designed to be much lower than the cement roads. “In this way, the water on the roads will be naturally drained into the green spaces,” said Zhang.
The pedestrian lanes in green spaces were all paved with permeable concrete, which allows rainfall to seep into the soil quickly. It solved the problem of waterlogged roads, and also helped the city conserve water resources, supplement groundwater, and form urban wetlands.
Another innovation is the revetment in the rainwater landscape zone, which has zigzagged the direct route of the original river channel and prolonged the filtration time for river water. The river course in the city has allowed the water to flow in from upstream and flow out downstream and then enter the urban wetlands directly. The drop of the water due to height differences has also created dissolved oxygen in the water, which helps to purify the water. Such a natural flood discharge channel is actually a small ecological system, which provides a corridor for the aquatic organisms discharged from the upstream flood, and is conducive to the formation of an interconnected and self-repairing aquatic ecosystem.
Meanwhile, aquatic plants have been introduced to absorb pollutants, weaken the eutrophic substances in the water body, and provide ecological space for aquatic and waterfront animals. Zhang said the calamus plant is able to absorb nitrogen efficiently because it depends on nitrogen to grow; while fish and shrimp can absorb phosphorus. So these aquatic animals and plants help improve the water quality. Compared with the previous mechanized factories, in which water was chemically treated to reach the purification standard before being discharged, the current practice has achieved zero pollutant emission. Its innovation lies in making full use of biodiversity for water environment management.
By using aquatic animals and plants to build a small aquatic ecosystem, the quality of the water environment has been greatly improved. Kunming’s success provides a model for managing the water environment in urban areas.
“In the future, we will plant more fruit trees to attract more birds, whose excrement can provide nutrients for aquatic plants. Fish eat shrimp, shrimp eat freshwater snails, and freshwater snails eat algae. In this way, an aquatic ecosystem is built, and the entire system has zero discharge of phosphorus and nitrogen,” said Zhang.
A beautiful view of the Baofeng Wetland on the east bank of Dianchi Lake in Kunming. Guo Wuhui
“Through these measures, the water quality is above Grade IV before entering the Dianchi Lake,” Zhang said, then added that the wetland not only has a high value landscape function, but also provides a green shelter for reducing pollution. Two groups of water samples were taken before and after the completion of an urban ecological wetland to monitor the water quality. After rounds of filtration and precipitation, the water quality has been upgraded from Grade IV to Grade III.
Nowadays, a livable and pleasant ecological landscape has formed in Kunming wetland parks. The wetland greenway opens up a new space for surrounding residents to exercise in the morning and evening, creating a friendly living environment as part of the symbiotic development of water, city, and people.
As a Chinese saying goes, “All beings flourish when they live in harmony and receive nourishment from nature.” Under the theme of “Ecological Civilization – Building a Shared Future for All Life on Earth,” the 15th Meeting of the Conference of the Parties (COP15) to the Convention on Biological Diversity has shown that the world is not only made up of human beings, and it does not merely belong to the current generation. Only if all beings flourish and live in harmony can we save the planet and achieve sustainable development. Protecting nature means protecting ourselves.