The part of Anzac Parade significantly flooded in June 2015 will be the first focus for Horizons Regional Council's flood resilience strategy.
The strategy will target the area where the flood led to resident displacement as well as damage to infrastructure and around 100 houses.
Horizons river management group manager Ramon Strong said it was time to make progress in adapting to an increased frequency of large floods as a result of climate change.
"We are starting with Anzac Parade as a significantly affected area, both because of the number of homes at risk and also as it's an important part of Whanganui," he said.
"It is lined with beautiful trees and is home to Kōwhai Park, a much-loved feature of the place."