Chinese artillerymen fired 105 rounds of ammunition to clear ice blockages along a section of the Yellow River in Urad Front Banner, Inner Mongolia Autonomous Region, Thursday.

Chinese artillerymen fire ammunition to clear ice blockages along a section of the Yellow River in Urad Front Banner, Inner Mongolia Autonomous Region, Thursday. [Xinhua]

Over two hours, the blockages, which extended 4 km at Hujiatuodan, were fragmented. The icy water then moved forward, said Yan Xingguang, an expert with the Inner Mongolia Yellow River Ice Blockage Prevention Headquarters.

Three air force bombers were used Wednesday to clear blockages along another section of the Yellow River in Dalad, about 20 km downstream from Hujiatuodan.

In Wednesday's mission, the bombers dropped some 9,000 kg of dynamite in three sorties and removed the blockage at the southern banks of the river at Putuobu in Engebei Township, Dalad, said Chen Xin, spokesman for the Inner Mongolia Yellow River Ice Blockage Prevention Headquarters. Wednesday's mission took 50 minutes.

Sections of the Yellow River, the second longest in China, freeze and thaw at different times. When an ice run flows to a frozen section, it can become blocked. If the blockage persists, water levels may rise and cause floods and dam bursts, threatening lives and property. The ice-run phenomenon takes place at the start of winter and spring.

Chen said Wednesday the section of the Yellow River that flows through Inner Mongolia thawed earlier this year than previous years, but the partly melted ice gathered to form blockages. The volume of floodwater in the region reached 1.7 billion cubic meters, surpassing that of last year.

The 5,464-km river originates in Qinghai Province in the northwest and flows through Gansu, Ningxia, Inner Mongolia, Shaanxi, Shanxi, Henan and Shandong before emptying into the Bohai Sea.

The main stream of the Yellow River in Inner Mongolia alone extends 830 km, of which 268 km has a riverbed about 17 meters above ground, said Yan.

"The result will be unimaginable if any part of the protective embankments fails. Right now, we can only be on alert and go all out to clear ice blockages to prevent a flood," said Yan. He declined to say when the ice-clearing process would end this year.