Swedish to English Tech/Engineering Law: Contract(s)

Hello,

Does anyone know what the standard translation of "skyfallsstråk" is in English?

The context in which I saw it has to do with the laying out of underground pipes and other facilities:

"Marknivåreglering för anslutning mot cykelbana och lågpunkt öster om planområdet [...]. Skyfallsstråk kombinerat med rening av vägdagvatten i grönytan från [gata] till skyfallsmagasinet i [statsdel]"

"skyfallsstråk" seems to be a device/system for containing or re-routing storm runoff, but I can't form a more exact picture than that.

Thanks