Hi Anne,
Two speculative suggestions.
The first one may be something to do with a cataract which means 'waterfall.'
The Biblical description of the garden of eden says :
Now a river flowed out of Eden to water the garden; and from there it divided and became four rivers. The name of the first is Pishon; it flows around the whole land of Havilah, where there is gold. The name of the second river is Gihon; it flows around the whole land of Cush. The name of the third river is Tigris; it flows east of Assyria And the fourth river is the Euphrates.
The more intelligent among us may have better solutions.
Blessings.