How Streamflow is Measured?

[Geek-9pm]

Can you help  me with this? OK, not a direct computer question, but about an algorithm and methods used in the real world to determine water flow in large canals and river beds.
How Streamflow is Measured
Part 2: The discharge measurement
https://water.usgs.gov/edu/streamflow2.html

The USGS uses numerous methods and types of equipment to measure velocity and cross-sectional area, including the following current meter and Acoustic Doppler Current Profiler.

I got behind  in school and never got into calculus. So if anybody here understands this, could he explain in simple language? 
Thank you, 

[Donutmuncher]

Since there are a variety of lengths and depths , there are many different methods to measure bodies of water. In the link you provided the first method shows how to calculate the discharge using the cross sectional of the stream and a current meter. A cross-sectional is basically a 2d slice of the stream with sections cut into equal width and a variable length (depth). In calculus its a similar process called Riemann sums in which you approximate the area underneath a curve using rectangles or trapezoids. You would basically calculate the area of each rectangle and add them together to find the approximation.

For discharge after you find the area of one rectangle you multiply by the the velocity that is calculated by the current meter in that subsection. Which gives you the discharge for one rectangle. You would then repeat this process for each subsection and add them together to find the total discharge.


ADCPs are much easier to work with for larger bodies of water and even ocean velocity measurements. Ships have adcps attached underneath the ship itself to calculate the velocity. There are many types of ADCPs, but all of them send out High frequency beams which change in frequency as it hits the water molecules and other particles. The beam is sent back to the ADCP, in which it uses that change to calculate the measurement. Different frequencies work better depending on the depth in which it is used at.

You can also look into Drifters as well as they are another method for measuring water flow.

My work currently is actually using the data gathered from different sources and comparing their measurements to predictions called (HYCOM). This is so engineers can improve on navigation and other devices needing the velocity measurements.  I just write programs all day to do these analyses as a job. 

[patio]

And your last code crashed for 2 days...you left that part out....

Welcome Aboard ! 

[Geek-9pm]

Donutmuncher,
  Think you for your response. I like to know how things work and how experts make calculations about water flow. I live jut south of Oroville and recently we were told to evacuate the downhearted of Oroville.
Many people speculated wholehearted area would be covered with water. Some distraught people said  everybody shroud run . My family was one of those that did not. While waiting, I was looking at some maps published by FEMA and the US geological survey and was wondering how  people imagined the whole area would flood. Water does not flow up hill, does it?
Anyway, you answer helped me understand thee is logic and reason in the calculations of water movement in a river or large body of water. Thanks for the details.
Actually, there really was a lot of damage from the huge  flow of water released  over the Lake Oroville spillways. But at no time was the city itself flooded.
Again, thinks for your  clear explanation of water flow measurements. 

[Donutmuncher]

And your last code crashed for 2 days...you left that part out....

Welcome Aboard ! 

It's the worst when you leave your code running during the weekend hoping to get more data analyzed. You just come in and see a random error occurred in the middle of it

Donutmuncher,
  Think you for your response. I like to know how things work and how experts make calculations about water flow. I live jut south of Oroville and recently we were told to evacuate the downhearted of Oroville.
Many people speculated wholehearted area would be covered with water. Some distraught people said  everybody shroud run . My family was one of those that did not. While waiting, I was looking at some maps published by FEMA and the US geological survey and was wondering how  people imagined the whole area would flood. Water does not flow up hill, does it?
Anyway, you answer helped me understand thee is logic and reason in the calculations of water movement in a river or large body of water. Thanks for the details.
Actually, there really was a lot of damage from the huge  flow of water released  over the Lake Oroville spillways. But at no time was the city itself flooded.
Again, thinks for your  clear explanation of water flow measurements. 

You're welcome! I hope the flood there causes little problems for you my friend. 


 

[Geek-9pm]

The flood had little impact on the place where we live.Infarct, this whole area did not flood. The flood was downstream. I dismayed that with all the technology available, so little  accurate information was available to the average person.

The damage was to the ecosystem.  They had to literally rescue fish for downing. really. The Feather River is home to species offish that only survive in fresh flowing water. When the water levels later dropped, the fish were trapped in muddy pools alongside the river backs.