The harmful plant is known to cause damage to buildings due to its penetrating roots.
But it is also threatening the stability of the Overstrand cliffs, which are frequently slipping into the sea due to erosion.
Material on the sea wall at Overstrand after the cliff slide where Japanese knotweed was found(Image: North Norfolk District Council)
The knotweed suppresses the growth of native species, adding to the risk of erosion as it leaves the cliffs bare when it dies off.
This increases the risk of water run-off destabilising the cliffs.
A large cliff slip earlier this year led North Norfolk District Council (NNDC) to block off the Overstrand sea wall.
It was later found that this cliff slip contained Japanese knotweed and the work to remove the plant has now been confirmed.
A spokesman for NNDC said: “Over the next eight weeks, work will be undertaken to remove the slip material, treat the Japanese knotweed on the cliffs and stabilise the slope.”
This week, material will be removed from the sea wall and disbursed locally.
Japanese knotweed can cause damage to buildings and other structures(Image: PA)
Weedkiller will be applied to the top and base of the cliff, before a contractor is brought in to remove the Japanese knotweed material from the sea wall.
Stabilisation work will then be undertaken at the bottom of the cliff.
It had been estimated that the works could cost up to £120,000, however, NNDC’s website says that the exact cost of the operation is still unknown.
“The council has established a budget for this, but the actual cost will not be known until the full extent is established,” it said.
Long-term, NNDC will monitor how the weed reacts to the treatment to keep track of the infestation and prevent further spread.
AloJapan.com