XINING, May 4 (Xinhua) -- Motorcycles roared through the morning mist on the Qinghai-Tibet Plateau, as Nyigye, 33, and his colleagues were on their way to work as rangers in the world's highest national park.

Snow is not rare to find in early April in Chumarle County of Yushu Tibetan Autonomous Prefecture, northwest China's Qinghai Province. As the source of the Yellow River, China's second-longest river, the area is deemed a core protection zone of the Sanjiangyuan National Park.

In the childhood memories of Nyigye, the area was plagued by severe ecological degradation. The deserted grassland was covered in rat holes, and the Yellow River's headwaters dried up, making drinking water a luxury for local people.

"We had to walk over a mile to fetch water every day," recalled Nyigye, a herdsman-turned-ranger at the national park.

Starting in 2015, China has launched 10 pilot national parks to protect the environment and biodiversity. The Sanjiangyuan area, home to the headwaters of the Yangtze, Yellow and Lancang rivers as well as over 60 wildlife species under state protection, is among the first batch.

As a flagship policy, each household living inside the 190,700-square-km park was offered a job opportunity as a ranger with an annual income of over 21,000 yuan (about 3,173 U.S. dollars).

According to Nyigye, rangers make regular patrols in the vast park on motorcycles. They are responsible for recording the water quality, preventing illegal poaching and mining, and treating injured wild animals, among a variety of tasks.

A patrol often takes five to six days, and sometimes rangers run into tough situations, for example, on rainy summer days, motorcycles often skid in the muddy grassland. "Sometimes the motorcycles break down somewhere without mobile reception and no maintenance personnel can be reached. Then we have no choice but to push the bikes," said Tsering Tashi, a colleague of Nyigye.

On the cold and oxygen-deprived plateau over 4,000 meters above sea level, hypertension and arthritis are common problems for rangers who are always trekking along mountains and rivers.

Despite these hardships, they feel content and proud of what they do. "Being a ranger pays me more than herding animals and benefits the environment of our homeland. I couldn't find a better job," said Tsering Tashi.

Nyigye couldn't help smiling while talking about how his job has influenced his six-year-old daughter. "My wife would tell her about my job, and now whenever my little girl sees empty bottles or plastic bags on the road, she picks them up and throws them into the trash can."

Over the years, the local government has implemented a series of policies and concrete results have been seen in restoring the environment of the "water tower" region.

"Since 2005, the amount of water coming into the Yellow River has increased significantly, and the headwaters of the river have flowed unimpeded for 18 years," said Han Changpeng, head of a protection station of the management bureau of the Sanjiangyuan National Park.

The annual runoff of the Yellow River, which is monitored at Huangheyan hydrological station, stood at 2.97 billion cubic meters in 2019, the largest figure on record since the institution started collecting data in 1955. In 2004, the runoff volume was a mere 26.27 million cubic meters.

Meanwhile, grassland coverage in the Sanjiangyuan area increased by 11 percent and grass output jumped 30 percent compared with a decade ago, official data in 2021 showed.

"Living in the region of the Yellow River's source, it is our bounden duty to protect the ecology, and the rangers are an indispensable force. With their endeavor, the river will flow ever eastward," said Tan Sheng, Party secretary of Chumarle County.