The surface area of China's largest inland saltwater lake has expanded further this year due to increased rainfall, the Qinghai Institute of Meteorological Sciences said Monday.

The surface area of Qinghai Lake, situated in northwest China's Qinghai Province, reached 4,476 square km in September 2017, an increase of 51 square km from the same period a year earlier, data from the institute showed.

The largest surface area on record was 4,477.53 square kilometers, which was documented in 1974.

Qinghai Lake plays an important role in the ecological security of the Qinghai-Tibet Plateau. The lake's water level dropped to the lowest recorded level in 2004, and since 2005, it has been expanding thanks to abundant precipitation in surrounding areas and increased snow melt due to climate change.

As precipitation levels are expected to stay high in September and October, experts believe the surface of the lake will continue growing this year.

"The expansion of the lake is beneficial for local ecological protection and the prevention of desertification in surrounding areas," said Liu Baokang, senior engineer at the institution.