Which term is used to denote the quantity of water moving through a river cross-section at a given moment?

Which term is used to denote the quantity of water moving through a river cross-section at a given moment?

• A. Flow rate
• B. Volume of water
• C. River speed
• D. Discharge

Answer: (D)

The quantity being tested is how much water passes a given cross-section of a river per unit time. The best term for this is discharge. It measures the volume of water flowing through that section each second and is calculated as the cross-sectional area of the channel multiplied by the average velocity of the water (Q = A × v). Its units are typically cubic metres per second (m^3/s). This is different from the total volume of water in the river at a moment (which would be a amount, not a rate) and from river speed (which is velocity, not the quantity flowing per time). While “flow rate” is sometimes used interchangeably in everyday language, the standard term in this context is discharge.

The quantity being tested is how much water passes a given cross-section of a river per unit time. The best term for this is discharge. It measures the volume of water flowing through that section each second and is calculated as the cross-sectional area of the channel multiplied by the average velocity of the water (Q = A × v). Its units are typically cubic metres per second (m^3/s). This is different from the total volume of water in the river at a moment (which would be a amount, not a rate) and from river speed (which is velocity, not the quantity flowing per time). While “flow rate” is sometimes used interchangeably in everyday language, the standard term in this context is discharge.