Question

With regard to stream gauging, what for the stage-discharge curve is used?

• A. To measure the width of the stream
• B. To measure the depth of the stream and presence of debris in the stream
• C. To find out change in velocity of the stream
• D. To relate the water level of a stream to its discharge

Hint:

• A stage-discharge curve (rating curve) is an empirical relationship developed for a specific stream gauging site.
• It plots stage (water level) against corresponding discharge (flow rate).
• Its main use is to allow for the estimation of discharge from continuous or periodic measurements of stage, as stage is easier to measure than discharge directly.
• This is crucial for hydrological studies, water resource management, and flood forecasting.

Answer 1

The Correct Option is D

To understand the purpose of a stage-discharge curve in stream gauging, we need to define what each term means and how they relate to each other.

1. Understanding the Concepts:

- Stream Gauging: The process of measuring streamflow (discharge) in a river or stream.
- Stage: The water level of the stream, typically measured relative to a datum or reference point.
- Discharge: The volume of water flowing past a point in the stream per unit time (e.g., cubic meters per second or cubic feet per second).
- Stage-Discharge Curve (Rating Curve): A graphical relationship between the stage (water level) and the discharge of a stream at a specific location.

2. Purpose of the Stage-Discharge Curve:

The stage-discharge curve is established by making a series of discharge measurements at different stages. Once established, it allows for the continuous estimation of discharge based on continuous stage measurements. This is far more efficient than continuously measuring discharge directly.

3. Evaluating the Options:

- Measuring the width of the stream is part of determining the cross-sectional area, which is used in discharge calculations but is not the direct purpose of the stage-discharge curve.
- Measuring the depth and presence of debris is related to stream conditions but not the primary use of the stage-discharge curve.
- The stage-discharge curve doesn't directly measure the change in velocity; it relates stage to discharge, which is related to velocity and cross-sectional area.
- The stage-discharge curve's fundamental purpose is to provide a relationship between water level (stage) and discharge.

Final Answer:

The stage-discharge curve is used To relate the water level of a stream to its discharge.