It happens all over the Santa Monica Mountains, chutes and holes and cracks in the rocks that channel the rainfall, make waterfalls. Here's a reliable rimfall, seen from the street formerly known as Debutts Terrace (and changed to I-forget-what by residents not comfortable with an address that sounds vaguely like a derriere.) The water runs here every time it rains, maybe even a bit fuller now after the fires. (And here it is again, a little closer up.)