Local residents and researchers play important roles in water protection in Nagchu, Xizang autonomous region — a city that serves as a strategic guarantee for water resources in China.

As such, it's also a core area for building an ecological security barrier.

Nagchu is situated between the Tanggula Mountains, Nyainqentanglha Mountains, Gangdise Mountains and the Kunlun Mountains, at an average altitude of 4,500 meters above sea level. The high-altitude region features vast areas of perennial snow on peaks and glaciers.

Nagchu has an inland glacier area of 6,780.26 square kilometers and totals 8,654.59 sq km, accounting for 31.58 percent of the total glacial coverage in China.

Thanks to its abundant snowpack, Nagchu is the source of major rivers in Asia, including the Yangtze, Nujiang, Lancang and Lhasa rivers. It has been called "Asia's water tower".

Knowing the importance of protecting the water ecology, the city government has hired thousands of residents to undertake the duties of patrolling the natural environment, including grasslands, lakes, glaciers, wetlands, rivers and forests.

Tsega, an ecological patrolman in Marchu township in Nagchu's Amdo county, is one of the hundreds of environmental guardians in the village. His home village is located near big glaciers that give birth to the Yangtze River — known as the Mother River of China.

The Marchu township government has designated more than 300 ecological caretakers to regularly conduct cleanups along the rivers and in wetlands, grasslands and the environment near glaciers, as well as in the villages.

"During every cleanup, villagers pick up plastic bags and beverage bottles, and they advise residents and visitors not to litter while traveling in the wilderness," the 70-year-old Tsega said.

"The rivers and streams that flow from here not only become drinking water for countless residents downstream but also serve as drinking water for all the wildlife inhabiting the river basins," he said.