Excavation of the final five tunnels of the Pearl River Delta water resources allocation project was completed over the weekend on Daling Mountain in Dongguan, Guangdong province, taking construction of the mega project to the next stage in which the raw tunnels will be lined with concrete.

The project has 48 tunnels, which have been under construction for 1,272 days, the Guangdong Water Resources Department said on Sunday.

"Completion of the final tunnels lays a solid foundation for realizing the goal of ensuring water supplies to major cities in the Guangdong-Hong Kong-Macao Greater Bay Area by the end of 2023," the department said.

The project, which stretches 113 kilometers, will draw water from Liyuzhou in Foshan's Shunde district in the western part of the Pearl River Delta and transport it to Guangzhou's Nansha district, as well as the cities of Dongguan and Shenzhen in the eastern part of the delta, it said.

"The project also will provide emergency standby water for the Hong Kong Special Administrative Region, Guangzhou's Panyu district, Foshan's Shunde district and other areas in Guangdong province, benefiting more than 50 million residents who live along the project, it said.

"The project, which cost more than 35.4 billion yuan ($5.13 billion), will be able to divert more than 1.7 billion cubic meters of Xijiang River water annually in the western part of Guangdong to the Dongjiang basin in Shenzhen in the eastern part upon completion, playing an important role in alleviating drinking water shortages in Shenzhen and Dongguan.

Construction started in the first half of 2019 and is expected to conclude in 60 months.

Most of the major water pipes are built from 40 to 60 meters underground to protect the ecology and environment and minimize land consumption, the department said.

It is the largest water conservancy project to be built in Guangdong province.