Chinese researchers are working on a scientific survey to measure the depths of major lakes in Hoh Xil in the northwestern part of the Qinghai-Tibet Plateau, the Chinese Academy of Sciences (CAS) said Wednesday.

They have for the first time obtained data of large and medium-sized lakes and drilled many lake cores, filling the gap of basic geographic information of lakes in the region.

The survey, led by the academy's Institute of Tibetan Plateau Research, is part of the country's second comprehensive scientific expedition to the Qinghai-Tibet Plateau.

The plateau, dubbed "the water tower of Asia," is one of the three major lake regions in China. It has a lake area of nearly 50,000 square km, accounting for about 2 percent of the total area of the plateau. According to researchers, lakes here have changed dramatically in recent decades, but there is a huge lack of data on lake depth and water quality.

Zhu Liping, lead of the research team, described the survey as a panoramic scan of lakes in Hoh Xil.

The research team has 28 members from five institutes including the CAS, Peking University and Nanjing University. They entered the Hoh Xil Nature Reserve on Oct 15, 2019, and spent 32 days traveling 1,400 km.

The survey shows that the lakes in Hoh Xil are shallower than similarly sized lakes in southern Tibet.

In recent decades, due to increased rainfall and shrinking glaciers, most lakes in the region have expanded by more than 20 percent. Their salinity, therefore, has declined.

Zhu said the research team has obtained data of more than 70 lakes covering 20,000 square km on the Qinghai-Tibet Plateau. It expects to complete the water depth measurement of nearly 100 lakes by the end of the expedition.

With data, researchers will estimate the amount of lake water and its changes and analyze its relationship with the region's climate, offering support for the study of the plateau and its response mechanism to global climate change.

Hoh Xil nature reserve is China's largest unpopulated area and a world heritage site, with thousands of wild animals such as yaks and Tibetan antelope.

China's first comprehensive scientific expedition to the plateau took place in the 1970s and the second that began in 2017 will last five to 10 years.