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How to Measure Water Currents

Current is the horizontal movement of water. According to the National Oceanic and Atmospheric Administration, current measurement is critical to marine commerce, ship navigation, recreational and commercial fishing, and for recreational beachgoers and surfers. It is also important for the kayakers and river rafters to know the current measurement so they can adjust and plan their movements properly. There are a number of different ways to measure the water currents.

Instructions

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  The first method uses the release of sound waves to determine current speed. This method needs a hydroacoustic current meter to measure the water velocity. This instrument works by releasing a high pitched "ping" sound into the water. The sound waves travel through the water and reflect back to the instrument. This process is called the Doppler effect. The water current is measured based on how long it took for the sound waves to bounce back to the instrument. You can position the instrument under the water or it can be mounted horizontally on seawalls or bridge pilings. You can also attach it to the bottoms of ships.
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  Another method is to toss an object into the water. According to the National Oceanic and Atmospheric Administration, you can measure the water current by simply tossing an object into the water and then timing how long it takes for the object to reach a certain point. Divide the distance by the time to calculate the water current. This method is usually used by river rafters and kayakers.
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  A third method is to use an electromagnetic current meter (ECM). According to the Virginia Institute of Marine Science, an ECM measures current by inducing a magnetic field around a spherical sensor head and then measuring the electromotive force that results from water moving through the field. The ECM used to be the only mechanical device available to measure water current. It works best in a controlled flow environment.

Nature