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Questions and Answers
Which channel shape results in less resistance and faster flow?
Which channel shape results in less resistance and faster flow?
The relief ratio is calculated using maximum relief divided by the shortest straight length.
The relief ratio is calculated using maximum relief divided by the shortest straight length.
False
What is the primary effect of stream patterns on a catchment area?
What is the primary effect of stream patterns on a catchment area?
They affect the draining period and the flow intensity of the surface.
A dendritic drainage pattern resembles a __________.
A dendritic drainage pattern resembles a __________.
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Match the types of drainage patterns with their descriptions:
Match the types of drainage patterns with their descriptions:
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What is streamflow primarily generated by?
What is streamflow primarily generated by?
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Streamflow can cease if groundwater levels are below the channel level.
Streamflow can cease if groundwater levels are below the channel level.
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What are some key factors that streamflow depends on?
What are some key factors that streamflow depends on?
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Streamflow is commonly expressed in units of cubic metres per second, abbreviated as _____ or cms.
Streamflow is commonly expressed in units of cubic metres per second, abbreviated as _____ or cms.
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Match the following terms with their definitions:
Match the following terms with their definitions:
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Which technique is NOT used for measuring streamflow?
Which technique is NOT used for measuring streamflow?
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Published streamflows are solely based on theoretical calculations.
Published streamflows are solely based on theoretical calculations.
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A watershed is also referred to as a drainage _____ or basin.
A watershed is also referred to as a drainage _____ or basin.
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What is the primary purpose of measuring the depth of a river at multiple points?
What is the primary purpose of measuring the depth of a river at multiple points?
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Using a flowmeter requires measuring the velocity at 50% of the total depth.
Using a flowmeter requires measuring the velocity at 50% of the total depth.
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What formula is used to calculate discharge when using a flowmeter?
What formula is used to calculate discharge when using a flowmeter?
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To estimate the average velocity accurately, the surface velocity is multiplied by ______.
To estimate the average velocity accurately, the surface velocity is multiplied by ______.
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Match the following methods of measuring stream properties with their descriptions:
Match the following methods of measuring stream properties with their descriptions:
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Which method provides a good estimate of stream velocity involving two people?
Which method provides a good estimate of stream velocity involving two people?
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The stage of a stream refers to the width of the water surface.
The stage of a stream refers to the width of the water surface.
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What is the most commonly used datum when measuring the stage of a stream?
What is the most commonly used datum when measuring the stage of a stream?
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Which type of stream flows only part of the year?
Which type of stream flows only part of the year?
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Ephemeral streams flow continuously throughout the year.
Ephemeral streams flow continuously throughout the year.
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What is the formula for calculating stream discharge?
What is the formula for calculating stream discharge?
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A stage hydrograph can be converted to a discharge curve using a _________.
A stage hydrograph can be converted to a discharge curve using a _________.
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Match the following stream characteristics with their definitions:
Match the following stream characteristics with their definitions:
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What is used to measure the flow depth of a stream over time?
What is used to measure the flow depth of a stream over time?
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The cross-sectional area of a stream is measured parallel to the flow.
The cross-sectional area of a stream is measured parallel to the flow.
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To determine stream discharge, one must measure velocity and the ___________.
To determine stream discharge, one must measure velocity and the ___________.
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Which of the following is a type of gage used in measuring water levels?
Which of the following is a type of gage used in measuring water levels?
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Rating curves are used to relate stage to velocity.
Rating curves are used to relate stage to velocity.
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What is the formula to calculate discharge based on cross-sectional area and average velocity?
What is the formula to calculate discharge based on cross-sectional area and average velocity?
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The ______ is used to obtain instantaneous discharge by measuring river stage.
The ______ is used to obtain instantaneous discharge by measuring river stage.
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Match the following weir types with their characteristics:
Match the following weir types with their characteristics:
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Which method is used to estimate surface velocity with a float and stopwatch?
Which method is used to estimate surface velocity with a float and stopwatch?
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The Manning's equation can be used to estimate discharge in open channel flow.
The Manning's equation can be used to estimate discharge in open channel flow.
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What is the range of the velocity correction factor (Kf) when estimating surface velocity with a float?
What is the range of the velocity correction factor (Kf) when estimating surface velocity with a float?
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The average flow velocity multiplied by the cross-sectional area gives the ______ of the stream.
The average flow velocity multiplied by the cross-sectional area gives the ______ of the stream.
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Which of the following factors is NOT used in Manning's equation?
Which of the following factors is NOT used in Manning's equation?
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Velocity methods for measuring discharge are not suitable for open channels.
Velocity methods for measuring discharge are not suitable for open channels.
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How can the cross-sectional area of flow (Af) be estimated?
How can the cross-sectional area of flow (Af) be estimated?
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Study Notes
Hydroloy (CEE335) Chapter 5: Stream Flow Measurement
- Streamflow is generated by snowmelt, rainfall, and groundwater entering a channel.
- During dry periods, streamflow can be sustained by groundwater discharge, but if groundwater levels fall below the channel level, streamflow ceases until the next storm or melt event.
- Streamflow generation is influenced by precipitation, overland flow, infiltration, and groundwater flow.
Streamflow Continued
- Knowledge of streamflow quantity and quality is crucial for water supply, flood control, reservoir design, hydroelectric generation, navigation, and wildlife management.
- Published streamflow data is based on field measurements. These include measurements from flow-measuring devices (weirs, flumes), channel cross-sections, flow velocities, and water levels.
- Daily streamflow is reported as a discharge (flow rate), which is the volume of water passing a specific point per unit of time. It's commonly expressed in cubic meters per second (m³/s) or cubic centimeters per second (cms).
Stream System Network
- Stream systems feature tributaries feeding into a trunk stream, which ultimately flows into a larger body of water (e.g., ocean).
- Headwaters represent the source of a stream system, and distributaries are channels that branch off a main stream.
Streamflow Factors
- Streamflow depends on factors including: stream area, slope, shape, flow length, and stream characteristics like location, density, and nature.
- The catchment area is the area of land that drains into a particular stream or water course. It's also known as the drainage area or watershed. Groundwater divides generally track surface divides.
Catchment Area
- The catchment area is the area of land that drains into a given point on a stream or watercourse.
- It is usually assumed that the groundwater divide coincides with the surface divide.
Effect of Shape
- Stream shape affects the timing and peak flow during storms.
- Different stream shapes (radial, elongated, divided) lead to different patterns of flow concentration.
Linear Measures
- Catchment length: the length along the primary watercourse to the centroid (often estimated as a point intersecting two or more straight lines).
- Stream order: hierarchical classification of streams based on the number of tributaries. Order 0 represents overland flow. Order 1 gets flow from order 0, Order 2 from 2 order 1 streams etc.
Slope/Catchment Relief
- Relief: the elevation difference between the highest and lowest points in a catchment.
- Relief ratio: the ratio of maximum relief to the longest straight-line length.
Channel Shape and Roughness
- Channel shape and roughness influence flow resistance.
- Narrow and deep channels have less resistance and faster flow, whereas wide and shallow channels have more resistance and slower flow.
- Rough streambeds create more resistance and slower flow.
Stream Patterns
- Stream patterns reflect geology, soil structure, and climate.
- Common stream patterns include dendritic (tree-like), radial, trellis, pinnate, anastomosing, parallel, and rectangular.
Stream Order
- Stream order is a hierarchical classification based on the number of tributaries joining a stream.
- Higher-order streams receive flow from lower-order streams.
Flow Regime Classifications
- Streams are classified as perennial (always flowing), intermittent (flowing only part of the year), or ephemeral (flowing only after rain).
- Flow regime reflects the influence of climate.
Stream Gauging Stations
- Gauging stations measure flow depth (stage) over time, resulting in a stage hydrograph.
- Gauging Stations are used to record flow depth (stage) as a function of time.
The Hydrograph
- A stage hydrograph shows stage as a function of time.
- A discharge hydrograph shows discharge as a function of time.
Discharge-Stage (Rating) Curve
- A rating curve depicts the relationship between stage and discharge.
- It's used to convert stage hydrographs into discharge hydrographs.
Stream Discharge Hydrograph and Hyetograph
- A stream discharge hydrograph is a plot of discharge versus time.
- A hyetograph is a plot of rainfall intensity versus time.
- The relationship between these graphs provides insights into runoff generation patterns.
Direct and Indirect Discharge Measurement Methods
- Direct measurement: involves measuring flow velocity and cross-sectional area of a channel.
- Indirect measurement: involves using high-water marks, structural characteristics, or fixed relationships between water stage & discharge rate (rating curve).
Methods for Measuring Stream Velocity
- Float method
- Current meter method.
Methods for Measuring Stream Depth
- Direct measurement: use tape measure to determine distance between stream surface and bottom.
- Partitioning the stream into segments and using depth measurements for each segment.
Calculating Cross-Sectional Area
- Using rectangles, trapezoids, and triangles to determine the cross-sectional area of a stream.
- Measurements of width and depth at various points across the stream section.
Measuring Stream Stage
- Non-recording stream gauges (staff gauges, crest gauges, debris lines) estimate stream stages.
- Recording gauges provide continuous measurements of the water level in a channel.
Relating Stage to Discharge
- Rating curves establish the relationship between stage and discharge.
- By defining a curve for the stream of interest, stage measurements may be made to calculate discharge.
Fixed Gauging Stations (Weirs)
- Weirs are structures with stable cross-sections and predefined geometry to simplify discharge calculation. Stage measurements suffice to determine discharge.
Open Channel Flow (Manning Equation)
- Open channel flow differs from pipe flow due to the water surface being subjected to atmospheric pressure.
- Manning's equation relates flow velocity to hydraulic radius, channel slope, and Manning's roughness coefficient.
Manning's Roughness Coefficients
- Manning's roughness coefficients reflect the resistance of different channel types to water flow.
Slope-Area Method for Discharge Determination
- For situations where velocity measurements are difficult, this method uses water level data (high-water lines) along with cross-sectional area and channel slopes to estimate discharge. Manning's equation is used.
Discharge Measurement in Channel Parshall Flumes
- Special waterways known as flume are used to measure stream and canal discharge. Measurements of stage and geometry allow computation of discharge.
Weir Experiment
- Weir experiments involve measuring discharge for different weir configurations (rectangular and triangular).
Relating Point Velocity to Cross-Sectional Flow Velocity
- Point velocities are important, but the goal is a method to translate them to the average cross-sectional flow velocity using methodologies like the mean-section method.
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Description
Test your knowledge on hydrology concepts related to streamflow and watershed management. This quiz covers topics such as drainage patterns, relief ratios, and measurement techniques. Get ready to dive deep into the intricacies of how water flows and its governing factors.
