Flood Gate

Flood Gates:
Door (left), & Dock.

Flood Gate

n. A metal barrier which may be positioned within a matching receptacle integrated into the frame of a GATE or door and pressurized in order to create a tight seal for the purposes of keeping flood waters out of the STORE, and thereby protecting property and INVENTORY.

NOTE: Yes, there have been occasions when I've seen these things being used. Once, the flood waters from the creek behind the STORE completely covered at least one car left in the back LOT, and finally crested just an inch or two below the lip of the DOCK. Too close for comfort.