Wang Yongping, a safety officer with the group, told media that efforts to close the dam have been extremely challenging. The dam section on the right side of the breach has become very fragile, which makes it impossible for heavy vehicles carrying construction materials to travel on, so all construction work has to be carried out from the left side, Wang said.

A total of 158 construction workers from the group have been working day and night in the heat to battle the flooding river.

The group has employed 39 pieces of construction equipment to fix the dam. Drones and unmanned ships have also been dispatched to monitor the Weihe's current to ensure construction work can be carried out effectively.