What is a weir and how does it work?

By definition, a weir is a man-made structure designed to alter a river’s flow characteristics and measure flow rates. A weir is a low lying barrier similar to a dam, but instead of stopping water significantly, it uses its structure to slow down or manipulate water flow for various purposes. Weirs come in various sizes and styles, all of which perform basically the same function, just via different methods.

The five major styles of weirs include: Labyrinth, Broad-Crested, Sharp-Crested (Fayoum), Compound, and V-Notch. Each have their own characteristics that can make that style the best for certain situations. A labyrinth weir uses a trapezoidal-shaped wall to increase wave length, making it a very versatile style. On the other hand, a sharp-crested (or Fayoum) weir allows water to fall clearly away from the weir and, under controlled conditions, can measure river flow rates with +/- 2% accuracy, making it a great style to use for certain types of research.

Weir structures can vary depending on their style and shape, but all perform many of the same functions. So, what are weirs used for? Weirs can be used to maintain the vertical profile of a lake or stream, to control invasive species in rivers, to measure river water flow, or even used to study salmon returning for their spawning season.

Weirs are man-made structures and are therefore put into an existing lake. For a weir to perform its intended function, it must make sure that water passes over or through it (depending on weir design) and not underneath it, where the water is neither controlled nor accurately measured. To keep the water flow rate measurement accurate, a weir has to be waterproofed in any area that is not intended for water to flow. For this you need a strong, durable waterproofing that can stand up to constant water pressure from an ever-flowing stream. Many waterproofers simply can’t handle that kind of steady water flow and will fail, causing problems with accurate readings and lessening control of water flow. SANI-TRED is a waterproofing material that does not fail, does not weaken, and will keep a water-tight seal for as long as a weir is in use.

Sure, you may not have a weir in your backyard, by definition, you probably don’t, but projects like this just go to show the seemingly limitless versatility of SANI-TRED waterproofing products. From basements to showers, garage floors to weirs, SANI-TRED can waterproof anything you need. That’s what sets SANI-TRED apart from other waterproofing products.

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