The main branch of the Xi River flows southeast through the delta entering the South China Sea at Modao Men, just west of Macau.

As for other functions, it plays a vital role in carbon storage and transport in Southern China.

[5] The Xi River is facing some ecological challenges such as drought,[6] invasive species,[7] and pollution.

Its volume of flow is second in China only to that of the Yangtze River, and it supplies water to many places in Guangxi, Guangdong and Macau.

Existing in many segments it extends for 2,271.8 km (1,411.6 mi): Rivers are a significant storage and transport system for both organic and inorganic carbon.

In the Nanpan River, carbon inputs come mainly from soil and organic detritus.

[10] In order to protect the Xi River, the Guangxi Zhuang Autonomous Region government issued a notice prohibiting new construction projects and migration of people within the land occupied and inundated areas of the Xi River mainstream control project in Guangxi.