Expenditure on flooding will be doubled, the chancellor has announced in the budget, but analysis has revealed that the figure is less generous than it seems. Spending will be increased to £5.2bn for the period from 2015 to 2021, but the extra £2.6bn that includes will be for capital projects only, with no extra funds for maintenance.

From the financial year 2015-16 to 2018-19, spending on flood defences was just over £3bn, and a further £815m was allocated for the financial year about to end. That comes to £3.9bn, of which about £1.3bn went on the maintenance of existing flood defences and other routine tasks.

If the chancellor were really doubling expenditure on flooding as he and his aides claimed, he would have allocated nearly £8bn. The capital spend will go on about 2,000 new projects, which will protect an estimated 330,000 homes currently without adequate defences.

Nothing was forthcoming from the Treasury on Wednesday on what would happen to non-capital spending on floods, and the Department for Environment, Food and Rural Affairs told the Guardian no details were likely to be available for several days. Maintaining existing defences is vital, however, as the failure of existing barriers – in some cases owing to poor upkeep – was a major factor in the recent damage wrought by the storms Ciara and Dennis.

“We do need the government to pay to repair defences that have been battered and breached by some of the wettest winter weather we’ve seen,” said Hannah Cloke, a professor of hydrology at the University of Reading. “The Environment Agency do a good job on this, but could do so much more if they were better funded.”

Ana Mijic, a senior lecturer in water management at Imperial College London, said that without a major rethink of how the UK used water and dealt with flooding, “we will keep fixing the problems rather than fundamentally changing the way we try to achieve sustainable development”.

The chancellor may also face searching questions from newly elected Conservative MPs from former Labour constituencies which were among the worst-affected by recent floods. Neil Parish, the chair of the environment, food and rural affairs committee of MPs, said the committee would scrutinise the plans when details became available.

“Vital questions remain about how funds will be allocated,” he said. “[We will be] assessing whether current arrangements for flood management are fit for purpose. We must learn lessons from this winter’s terrible storms.”

Emma Howard Boyd, chair of the Environment Agency, welcomed the chancellor’s announcement. “Flooding is an awful experience for people to go through and damaging to the economy,” she said. “People want to be warned and protected, and where that isn’t possible, they want to be able to get back to normal quickly. Today’s £5.2bn for flood protection is hugely significant to the resilience of the UK. As the climate emergency increases flood risk, this will allow us to invest in infrastructure and nature-based solutions.”

Funding for trees and peatland

Sixty million trees will be planted over the next five years to capture climate-heating carbon and boost wildlife, the chancellor Rishi Sunak has said.

But the 30,000 hectare plan was immediately denounced as inadequate. The government’s official advisers, the committee on climate change (CCC), say trees must be planted five times faster to tackle the climate emergency effectively.

Sunak also said 35,000 hectares of carbon-rich peatland would be restored by 2025. Both the peatland restoration and tree planting are funded by a new £640m Nature for Climate fund. “This government intends to be the first in history to leave our natural environment in a better state than we found it,” said the chancellor.

Chaitanya Kumar of the Green Alliance said: “Thirty-five thousand hectares of peat is only around 1% of the UK peatlands. The CCC has suggested we need to restore at least 50% of upland peat and 25% of lowland peat to get on track to net-zero emissions, so clearly greater ambition is needed.”

“Used wisely, tree-planting, peatland restoration and funding for the Nature Recovery Network could really help nature adapt to our rapidly changing climate and sequester carbon,” said Prof Simon Lewis of University College London.