V-notch Weir

{
  "id": "MLC-T-ENV-029799",
  "term": "V-notch Weir",
  "field": "Environment",
  "definition": "A weir is an obstruction placed across the entire width of an open channel or conduit to interrupt flow and cause the fluid level upstream of the weir to rise until fluid flows over the top of the weir. With a properly constructed weir, critical flow will exist near the weir crest. Thus only one depth of flow can exist for a given discharge, and an equation can be developed that relates volumetric fluid flowrate over the weir with height of the surface of the fluid pooled upstream of the weir.The fundamental equation for a v-notch weir is Q = Cd(8/15) (2g)0.5 tan(x/2)H5/2 where: Q = flow (m³ / s) Cd = coefficient of discharge that relates actual flow to theoretical flow g = the acceleration due to gravity = 9.81 m /s² x = the angle between the two sides of the v-notch H = the height of the water upstream of the weir relative to the weir crest, measured at a point at least 4H upstream of the weir.",
  "subject": "Science and research",
  "references": [
    "Urban Watershed Management Research Terminology"
  ],
  "url": "https://mlchart.com/terminology/environment/v-notch-weir/"
}