What is a weir?
A low dam built across a stream to raise its level or divert its flow.
A weir is an underwater dam created to reduce, but not stop the flow of water in a river or stream.
Say you have a stream running through a property and you wanted to create a pond. Once you had located a suitable spot, you would install a weir which would back up the flow until the desired level was reached in the pond. Then the water would overflow the weir.
An important example on a bigger scale is the declining water levels in the North American great lakes, specifically lake Huron. The increased flow of water through the St. Clair river due to dredging and subseequent unexpected erosion has resulted in a net loss of water in the range of 835 million gallons per day. There is an environmental/political movement afoot to install a weir in the St. Clair river with the top of the weri well below the current water level. This would reduce the flow of water through the river and restore the water levels in lake Huron.
A weir is a small overflow-type dam commonly used to raise the level of a river or stream. Weirs have traditionally been used to create mill ponds in such places. Water flows over the top of a weir, although some weirs have sluice gates which release water at a level below the top of the weir. The crest of an overflow spillway on a large dam is often called a weir.
What is a Weir? A Mike Weir??
Why, A great Canadian Golfer!!! That’s what!