weir types

Common to a huge percentage of watershapes, weirs play starring roles in the performance of everything from vanishing edges to naturalistic waterfalls. But common does not mean simple, says hydraulics expert Steve Gutai, who takes this opportunity to explore the physical characteristics of weir types, the ways they influence hydraulic design and basic approaches watershapers can use to keep things straight when pushing water over an edge.

Over the Edge

From the grandest waterfall to the smallest courtyard fountain, water flowing over an edge is one of the most compelling of all watershaping “looks.” Whether it’s a vanishing edge or a slot overflow or a trough, runnel or waterfall, these effects all use one common concept – that is, the weir. Simply defined, a weir is a barrier or dam placed in a channel behind which fluid backs up and then falls through a notch and down the face of the weir. In most watershaping applications, water travels over the weir’s edge or brink and into some kind of lower basin, trough or pool. Physically and visually, these systems are driven by