Ten years ago Sir David King, the chief scientist, warned that existing policies on flooding were not an option … "Hard choices need to be taken – we must either invest more in sustainable approaches to flood and coastal management or learn to live with increased flooding."

The floods foresight report in which he sounded the warning explained what King meant by "sustainable" approaches to flood and coastal management, and it doesn't mean dredging. Sustainable flood management actually involves a lot less flood management and a lot more managed flooding.

His message underpins the 2010 Floods and Water Act. It has been accepted by Defra, adopted by the Environment Agency and acted upon by the local authorities; UK flood management is changing – unfortunately, the string of devastating floods, including the current disaster in Somerset, suggests that it isn't changing fast enough. The latest flooding is causing scientists and engineers to rethink their predictions that increases in flooding, driven by climate change, won't really kick in until the 2030s; that now looks over-optimistic. A causal link to climate change cannot be proved for any of the recent events, but they are precisely the type of floods that the Foresight team feared and forecast in 2004 – they've just arrived a couple of decades earlier than expected.

So what's to be done? What are the "hard choices" to which King alluded in 2004? Perhaps the best way to consider them is in relation to the three major causes of flooding: coastal, river, and surface water.

The enormous volumes of water and geographical scale of coastal flooding set it apart from the other two and, as an island nation with extensive areas of densely populated, low-lying land along our coasts and estuaries, we are especially vulnerable. Let's be clear: we cannot hold the line everywhere – it would cost too much and would destroy irreplaceable shoreline ecosystems through "coastal squeeze".

The Dutch take coastal protection very seriously indeed and they're very good at it too – even they now plan for and allow their coast to adjust to accommodate changing tides, waves and currents through "managed retreat". No, the future for coastal management in the UK will involve realigning defences by retiring them landward. The difficult choices for government are not in deciding where, or how much to retreat, but rather in finding equitable ways to relocate and, perhaps, compensating those affected for their financial losses and personal sacrifices.

River flooding is also a serious problem and risks are growing, but scientists, engineers and perhaps most crucially, catchment managers are well aware of what needs to be done. We understand enough of the water cycle to realise that "natural flood management", based on working with natural processes to increase infiltration, detain water within headwater catchments and restore meanders and large wood in rivers (even perhaps reintroducing beavers to manage that wood) can help. Natural flood management is part of the solution, but so is enhanced channel management, which will occasionally require removing silt from channels where their flood defence function is compromised.

Rivers are condominiums – resources shared by multiple stakeholders, and we expect them to look and be healthy, providing a range of ecosystem services vital for people's wellbeing. The hard decision here is for government to resist calls to revert to dredging and channelisation – approaches that have been found wanting in the past and would be again in the future. These calls are understandable but ultimately mistaken – sometimes the difficulty lies not in accepting new ideas but in letting go of the old ones.

Lastly, and perhaps most crucially, we have hard choices to make concerning urban flood risks. Our cities rely largely on Victorian pipe and surface drains, often combined with sewer systems (Combined Sewer Overflows, or CSOs), that were never designed to handle rainstorms with the intensity and duration to which they're now subjected. When a CSO occurs, raw sewage mixed with flood water enters our streams and may overflow into our communities. The first hard decision is to separate storm water from sewage – this reduces the damage, misery and health impacts of urban flooding but at a considerable replacement cost. People say this can't be done – we must not believe them. Portland, Oregon, proves it can be done. In 2008 as part of a city-wide "gray to green initiative", they decided to get rid of their main CSO; just six years later, it's gone, and good riddance.

The other hard choice lies in deciding how to cope with the effects of climate change without restricting economic growth. Planners have the answer, and it's not by relaxing controls on building in flood-prone areas in order to gain quick wins at the expense of competitor cities or even countries. It's by reinventing the way we manage the urban water cycle and making it a lot more like the natural cycle – recharging aquifers and surface-water stores in times of abundance to get us through what are likely to be increasingly frequent and protracted droughts. This is what Prof Cedo Maksimovic of Imperial College calls the blue-green dream. The "blue-green city" will use green spaces and corridors that turn blue during floods – reducing pressures on the pipe network while providing a wealth of benefits to citizens the rest of the time. The "Blue-Green Cities Research Consortium" is working out how this can be achieved, using Newcastle (ravaged by the Toon Monsoon in 2012, as its case study. Think it can't be done? Ask the people of Melbourne – they're at least a decade ahead of us, and their experience is just as compelling as Portland's move away from CSOs.

The good news with respect to future flood risk in the UK is that, although time is shorter than was thought, we can still avoid a difficult, costly and socially disruptive flood future. Reverting to past policies is not an option and hard choices have to be taken now – unless people and communities are going to learn to live with flooding.