Higher defences will not be enough on their own to deal with flooding, the Environment Agency's chief executive said as parts of the UK braced themselves for more heavy rain.
Sir James Bevan said people and communities should be helped to become more resilient when homes and businesses are inundated as he defended the EA's handling of the crisis.
Sir James was speaking following criticism of EA chairman Sir Philip Dilley's family holiday in Barbados at a time when parts of northern England were under water and as further heavy rain was predicted for parts of England and north-east Scotland.
"What everybody has said to me in the places I have visited up and down the country is that something has changed and that they have never seen anything like this and we need to think about what that means," Sir James told Radio 4's Today programme.
"Partly it will mean stronger flood defences but I don't think the solution is just to build up flood defences higher.
"Partly it will mean thinking much more broadly about how we manage river catchments, so water doesn't come straight down from the sky and straight into the rivers, so that we can slow the flow.
"I also think it is going to mean ... it's not just about better protection for people from floods, though that's a key part of it, it's about helping people and communities be more resilient when flooding actually happens."
On the criticism of Sir Philip, he said: "The person who is in charge of leading the Environment Agency's response to the floods crisis is me. Sir Philip Dilley's job is to hold me to account, he is doing that."
Eastern parts of Scotland are likely to be worst affected by further heavy rain across the UK over the next few days, the Met Office said, with some areas likely to see more than 200mm of rain between Saturday and Monday.
Met Office chief meteorologist Frank Saunders said: "We expect heavy and persistent rain to affect parts of eastern Scotland over the next few days, and have already issued national severe weather warnings for its potential impacts.
"Everyone should be aware of the potential for disruption in places from further flooding especially in areas such as Perth and Kinross, Angus and Aberdeenshire, where amber 'be prepared' warnings are in place."
Vincent Fitzsimons, the Scottish Environment Protection Agency (SEPA) hydrology duty manager, said: "Flood impacts may affect communities and cause disruption to travel and infrastructure from Tayside to Angus to Aberdeenshire over the coming days.
"Localised flooding is also possible in parts of the Scottish Borders, and in Caithness and Sutherland during Sunday and Monday."
Police said the A93 between Ballater and Braemar remains closed until repairs can be carried out and the Invercauld Bridge is expected to be closed to traffic for some weeks.
Chief Inspector Richard Craig said: "We are continuing to work with other agencies following the impact of Storm Frank across the Grampian region, particularly in Ballater, Crathie and Braemar, and are also preparing for further rain and potential flooding.
"Due to the warnings in place, we are asking people to stay away from rivers and already flooded areas so you don't put yourself in danger or place further burden on communities that have been impacted by the flooding."
Aberdeenshire Council's duty emergency response co-ordinator Ritchie Johnson said: "A concerted effort is taking place to respond to the weather situation in Deeside and across Aberdeenshire in light of warnings in place from SEPA and the Met Office and working closely with partners, colleagues and the community.
"There are access issues into Braemar and we are working with Police Scotland and neighbouring authorities to ensure access south remains in place with the aim of protecting the road."
The EA said more rain is expected on Sunday in south-west and north-east England and this will bring a risk of flooding along parts of some rivers in Devon and Cornwall and the North East.
It said the River Ouse is set to remain high in York for several days and the River Severn will remain high in places, bringing a low risk of flooding over the weekend and into next week in Shropshire, Telford and Wrekin, Worcestershire and Gloucestershire.
Temporary defences have been deployed in Shrewsbury and Bewdley.