A large crack has opened up alongside the Monmouthshire & Brecon Canal due to bad weather.
Rain had made the bank unstable. The canal has been closed between Govilon and Llanfoist while repairs are being carried out.
Winds in the area reached speeds of more than 50mph on Saturday night.
Coastal and flood-prone communities across Wales are preparing themselves for another battering from the weather this weekend
Ceredigion Council estimates that damage in Aberystwyth and elsewhere in the country will top £1.5m.