You may have seen this graphic, or some similar sentiment, doing the rounds at the moment.
As you may be aware, successive governments have committed to spending 0.7% of GDP on aid to some of the poorest and most needy people around the world. It’s also a tiny amount of money. The plot below makes this clear: it’s a small amount even of the interest the government pays on its national debt, and (not plotted) about a twentieth of what we spend on pensions each year.
So, practically, firstly, stopping this money would make little difference to the government’s overall budget. Bear in mind that the deficit is still much larger than 0.7% of GDP.
Secondly, there are many, many things that the government spends lots of money on that might be better reconsidered if there is a need to cut other things before we spend more money on flood defences (and helping those affected by the floods).
Third, as we’ll learn about this coming term, governments have budget constraints, and if they spend more than they get in tax receipts they run a deficit (as the UK government has done for a long time now), and need to borrow. As such, if something is important (hence has a good rate of return, however measured), and can be financed at a low interest rate (as is the case at the moment), then a better argument is that it should be funded by more borrowing.