winterbourne

1. (British) A stream that only flows in winter or after wet weather, particularly in an area rich in limestone.Examples: "[F]rom the graveyard itself burst up one of those noble springs known as winter-bournes in the chalk ranges, which, awakened in autumn from the abysses to which it had shrunk during the summer's drought, was hurrying down upon its six months' course, a broad sheet of oily silver, over a temporary channel of smooth green sward."; "The stream is a winterbourne - it flows only in winter or other periods of high rainfall and is usually dry in summer."British