Having come across NinetyWt’s old thread about damn break analysis in my bookmarks, and recently seeing the thought-provoking commercials telling us to get flood insurance*, I have to wonder. I have relatives in suburban Chicago, whose basement was flooded one year. The local stream that did it, when I visited, is in normal times just a tiny brook you can practially step across. I did say “step”, not “leap”. Yet that stream, that runs through a small park across the street from their house, swelled to the point where it flooded my uncle’s basement.
But they are in the heart of the ultrawet Great Lakes and upper Mississippi Valley region, which is probably the wettest part of the country outside the Pacific Northwest. I, on the other hand, live in West Los Angeles, which is one of the driest. Nevertheless, the land parcel directly to the north of my building–and upstream of it–contains an ancient artesian spring sacred to the native Tongva people, who called the place Kiruvungna, “the place where we are in the sun”. Junipero Serra’s party camped there on their way through Alta California, and were given watercress and chia, just as our biology teacher did when he toured us through the grounds.
Usually the water from the spring runs along a short channel to a beautiful pond, set with water lilies, filled with carp and tadpoles, and attended by dragonflies and the occasional water birds of the egret type. Strangely, I can’t remember ever seeing or hearing ducks, as powerful an attraction as you would think this place would be fore them. From the pond, the water runs through another channel and disappears into drain which I imagine leads into the storm drain system. In times of drought or surplus, the flow barely changes at all, and is about 26,000 gallons a day. My question is, could an extroardinarily heavy rain cause the spring to jump its system and spill out over the blocks below it? I only rent, and I think my apartment itself is safe, but we do park our cars in a subterranean garage.