In hydrology, the rate at which water flows through a point per unit time?

• A. Runoff
• B. Volume
• C. Flow rate
• D. Discharge

Answer: (D)

In hydrology, the rate at which water flows through a cross-section per unit time is called discharge. It represents how much water passes a point in a given second and is measured in cubic metres per second (m³/s). Discharge can be found from the cross-sectional area times the average velocity (Q = A × v) or by integrating the velocity over the area. This is different from runoff, which describes water moving over the land surface, and from volume, which is the total amount of water, not the rate. While flow rate is a general term for rate of flow, discharge is the standard term used for water moving through a cross-section per unit time.