Aid groups predict Tonga's Ha'apai islands, which bore the brunt of tropical cyclone Ian, will take several years to get back to normality.
There are fears the cyclone damaged fresh water supplies and arable soil has been polluted by salt water.
Boat and plane loads of crucial supplies are being delivered to northern areas of Tonga on Monday, devastated after Cyclone Ian killed one person and left thousands homeless.
The director of Tonga's National Emergency Office, Leveni Aho, says they are using radio and satellite phones to communicate with the stricken islands where electricity and phone lines are down.
He says the first supplies are now being delivered to those areas.
"We have already got two patrol boats in the islands, several flights going out now and there is a boat going out in the afternoon and we are coordinating relief supplies going out in the Fiords."
Leveni Aho says the relief co-ordination is targeted towards about 4000 displaced people who live on three of the islands in the Ha'apai group.