A Four-Step Guide to Accurately Calculating Surface Water Discharge

Today, a wide range of government agencies, municipalities, utility companies, and private companies need to monitor water flow in rivers, streams, and canals for a variety of reasons ranging from predicting water availability and flood events to allocating water resources and planning for future development. At a high-level, these organizations are concerned with the water flow and discharge of the surface water in a particular area. More specifically, water discharge, which is the volume of water moving through the cross section of a stream or river during a particular unit of time, is typically computed by multiplying the area of water in a channel cross section by the average velocity of the water in that cross section. This measurement is commonly expressed in cubic feet per second or gallons per day. Discharge measurements also take into account any suspended solids, dissolved chemicals, or biologic materials that are transported in the water through the cross section as well.
This whitepaper will provide a general guide for taking the necessary steps to calculate accurate surface water discharge measurements, including considerations for selecting the most ideal monitoring site, the technologies available for various site conditions, and how to ensure your systems continuously provides accurate data through modern quality assurance and quality control (QA/QC) methods.

Discharge

Download the full white paper with step instructions to accurately calculating Surface Water Discharge – click here

More discharge product description for mobile and continuous application see at www.ott.com

 

Water Flow and Discharge Measurement with the OTT MF pro

The OTT MF pro water velocity meter is a popular choice for water flow and discharge measurement in rivers, streams, and open channels. Today we’ll take an in-depth look at the science behind the meter and provide tips on how to get the best data from the meter in a variety of conditions.

Measurement principle

The OTT MF pro water velocity measurement is based on the Faraday principle (electromagnetic induction) which states that a moving conductor in a magnetic field will generate a voltage proportional to the speed of the conductor.  The MF pro sensor generates a vertical magnetic field near the center of the probe using an electromagnet.  This magnetic field is strongest near the sensor body and diminishes approximately 1/D² moving away from the sensor, where D is the diameter of the sensor. Water is a moving conductor and when velocity vectors flow straight into the sensor, the flow direction is perpendicular to magnetic field of the sensor.  Within this magnetic field a voltage proportional to the speed of the water is produced.  The sensor electrodes measure the voltage and the instrument calculates the speed of the water, refer to Figure 1.

Figure 1. MF pro sensor illustrating magnetic field and position of electrodes used for measuring voltage.

Figure 1. MF pro sensor illustrating magnetic field and position of electrodes used for measuring voltage.

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