Editing Flow measurement (section)

===Level to flow===
The level of the water is measured at a designated point behind [[weir]] or in [[flume]] using various secondary devices (bubblers, ultrasonic, float, and differential pressure are common methods). This depth is converted to a flow rate according to a theoretical formula of the form <math>Q=KH^X</math> where <math>Q</math> is the flow rate, <math>K</math> is a constant, <math>H</math> is the water level, and <math>X</math> is an exponent which varies with the device used; or it is converted according to empirically derived level/flow data points (a "flow curve"). The flow rate can then be integrated over time into volumetric flow. Level to flow devices are commonly used to measure the flow of surface waters (springs, streams, and rivers), industrial discharges, and sewage. Of these, [[weirs]] are used on flow streams with low solids (typically surface waters), while flumes are used on flows containing low or high solids contents.<ref name=" Hydraulic structures ">{{cite web|url=http://help.openchannelflow.com/customer/portal/articles/949768-hydraulic-structures-primary-devices---flumes-and-weirs|title=Desk.com – Site Not Found (Subdomain Does Not Exist)|website=help.openchannelflow.com|url-status=live|archive-url=https://web.archive.org/web/20150925133652/http://help.openchannelflow.com/customer/portal/articles/949768-hydraulic-structures-primary-devices---flumes-and-weirs|archive-date=25 September 2015}}</ref>