Search results
Results from the WOW.Com Content Network
This is an average measure. For measuring the discharge of a river we need a different method and the most common is the 'area-velocity' method. The area is the cross sectional area across a river and the average velocity across that section needs to be measured for a unit time, commonly a minute.
The first routine measurements of river flow in England began on the Thames and Lea in the 1880s, [2] and in Scotland on the River Garry in 1913. [3] The national gauging station network was established in its current form by the early 1970s and consists of approximately 1500 flow measurement stations supplemented by a variable number of temporary monitoring sites. [2]
In oceanography, the sverdrup (symbol: Sv) is a non-SI metric unit of volumetric flow rate, with 1 Sv equal to 1 million cubic metres per second (264,172,052 US gal/s). [1] [2] It is equivalent to the SI derived unit cubic hectometer per second (symbol: hm 3 /s or hm 3 ⋅s −1): 1 Sv is equal to 1 hm 3 /s.
Measure a length of stream, and mark the start and finish points. The longest length without changing stream conditions is desired to obtain the most accurate measurement. Place an orange at the starting point and measure the time for it to reach the finish point with a stopwatch. Repeat this at least three times and average the measurement times.
Velocity times the cross-sectional area yields a flow rate which can be integrated into volumetric flow. There are two types of area velocity flowmeter: (1) wetted; and (2) non-contact. Wetted area velocity sensors have to be typically mounted on the bottom of a channel or river and use Doppler to measure the velocity of the entrained particles.
The traveling time of sound waves gives an estimate of the distance. The frequency shift of the echo is proportional to the water velocity along the acoustic path. To measure 3D velocities, at least three beams are required. In rivers, only the 2D velocity is relevant and ADCPs typically have two beams.
Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!
Stream power, originally derived by R. A. Bagnold in the 1960s, is the amount of energy the water in a river or stream is exerting on the sides and bottom of the river. [1] Stream power is the result of multiplying the density of the water, the acceleration of the water due to gravity, the volume of water flowing through the river, and the ...