Any moves to modify the Los Angeles River, to return parts of it to a more natural setting or to capture water, need to be implemented with care.
Scientists say the key job of the concrete channel, which has featured in countless films and pop videos, is to protect the city from damaging floods.
And that role is likely to become more challenging if climate change brings heavier rains, they argue.
Alternatives to the river's current brutalism will not be easy to find.
"This is not a simple problem; it's not a matter, for example, of taking out half the concrete," said Bill Patzert from Nasa's Jet Propulsion Laboratory.
"One of the things the river attempts to do is to move water rapidly - the particular design, the angle, the slickness of concrete. It does that brilliantly.
"We've done something right through the middle of one of the most densely populated places in the world, and redesigning it is going to be very difficult."
Dr Paterzt and colleagues submitted an abstract on the topic to this year's American Geophysical Union Fall Meeting.
They are conducting research that seeks a vision for a "greener" LA River.