I recently had to put together a one-page summary of my PhD topic - and I've actually found it incredibly useful for explaining what it is I'm trying to do.
It was theoretically written for other academics who may not be experts on green infrastructure, or flood risk management, but will have some understanding of the field.
But actually, it's been most useful in relating to people who are outside of academia: my friends and family who repeatedly ask what I am doing because they really want to be interested and they really want to support me, but... It's not the most transparent topic, and there's a trade off between the short, jargon-heavy description and the long, less technical but very wooly description.
But in its written form, with an indication of context, and time to digest the wording, it's proved a lot more understandable!
So without further ado, my research topic in one page: