This Peter Gabriel song initially appeared on his first solo album (Peter Gabriel, 1977) and was re-recorded for Robert Fripp's 1979 album Exposure. The later version also appears on Gabriel's 'best of' compilation Shaking the Tree. On Exposure, it segues from a tape of J.G. Bennett (whose International Academy for Continuous Education Fripp attended at Sherbourne House) theorizing about climate change:
From the scientist's study it seems likely that we should soon begin to have a discreet change in the earth's climate so people will not be able to live where they have, and the oceans will rise, and many cities will be flooded, like London, and Calcutta, and so on. These things, they say, will happen, according to scientific theories, in about forty years at the most, but maybe even quicker.
Certainly, the lyric can be read in the light of this idea, but my impression (both when I first heard it in the 80s, and still today) is that it's more metaphorical, perhaps to do with the deluge of information and new technology that was just then beginning to pick up steam.

The first recording (which I haven't heard) has a full band, but on Exposure, the arrangement is very simple - mostly just Gabriel's soulful voice and an acoustic piano.

Here Comes The Flood - Peter Gabriel


When the night shows
the signals grow on radios
All the strange things
they come and go, as early warnings
Stranded starfish have no place to hide
still waiting for the swollen Easter tide
There's no point in direction
we cannot even choose a side.

I took the old track
the hollow shoulder, across the waters
On the tall cliffs
they were getting older, sons and daughters
The jaded underworld was riding high
Waves of steel hurled metal at the sky
and as the nail sunk in the cloud, the rain
was warm and soaked the crowd.

Lord, here comes the flood
We'll say goodbye to flesh and blood
If again the seas are silent
in any still alive
It'll be those who gave their island to survive
Drink up, dreamers, you're running dry.

When the flood calls
You have no home, you have no walls
In the thunder crash
You're a thousand minds, within a flash
Don't be afraid to cry at what you see
The actor's gone, there's only you and me
And if we break before the dawn,
they'll use up what we used to be.

Lord, here comes the flood
We'll say goodbye to flesh and blood
If again the seas are silent
in any still alive
It'll be those who gave their island to survive
Drink up, dreamers, you're running dry.

--Peter Gabriel, 1979


Robert Fripp, Exposure, EG Records (EGCD 41) UK 1979