Podcast
Questions and Answers
Which land cover type has the highest coefficient of runoff?
Which land cover type has the highest coefficient of runoff?
- Roofed Area
- Water/Pond (correct)
- Industrial
- Residential
The coefficient of runoff for open spaces is generally higher than that for gravel surfaces.
The coefficient of runoff for open spaces is generally higher than that for gravel surfaces.
False (B)
What is the coefficient of runoff for a residential area?
What is the coefficient of runoff for a residential area?
0.63
The coefficient of runoff for water/pond is __________.
The coefficient of runoff for water/pond is __________.
Match the land cover types with their respective coefficients of runoff:
Match the land cover types with their respective coefficients of runoff:
Considering the areal average runoff coefficient, what is the average coefficient for open spaces?
Considering the areal average runoff coefficient, what is the average coefficient for open spaces?
Name one area where the coefficient of runoff is 0.8.
Name one area where the coefficient of runoff is 0.8.
Gravel surfaces have a higher coefficient of runoff than residential areas.
Gravel surfaces have a higher coefficient of runoff than residential areas.
What is the primary focus of the discussed topics?
What is the primary focus of the discussed topics?
The Rational Method is used for calculating runoff from a watershed.
The Rational Method is used for calculating runoff from a watershed.
What does the term 'design rainfall intensity (I)' refer to?
What does the term 'design rainfall intensity (I)' refer to?
The _____ Method is a variation of the Rational Method used for runoff analysis.
The _____ Method is a variation of the Rational Method used for runoff analysis.
Match the following methods to their descriptions:
Match the following methods to their descriptions:
What is the highest rainfall intensity recorded for a return period of 100 years over a duration of 1 hour?
What is the highest rainfall intensity recorded for a return period of 100 years over a duration of 1 hour?
The overland flow time (To) is calculated using 107 times the number of years of rainfall.
The overland flow time (To) is calculated using 107 times the number of years of rainfall.
Which of the following is NOT a topic discussed in the content?
Which of the following is NOT a topic discussed in the content?
Design rainfall intensity is measured in cubic meters per square meter.
Design rainfall intensity is measured in cubic meters per square meter.
What does Tc represent in stormwater management?
What does Tc represent in stormwater management?
List one application of the rainfall-runoff analysis.
List one application of the rainfall-runoff analysis.
The formula for calculating travel time through channels and pipes is __________.
The formula for calculating travel time through channels and pipes is __________.
Match the following return periods with their corresponding rainfall intensities for a 30-minute duration:
Match the following return periods with their corresponding rainfall intensities for a 30-minute duration:
What is the minimum velocity stated for Vmin in Manning’s Equation?
What is the minimum velocity stated for Vmin in Manning’s Equation?
A rolling hill area flooded after 15 minutes of rainfall supports the estimation of the time of concentration.
A rolling hill area flooded after 15 minutes of rainfall supports the estimation of the time of concentration.
In the formula V = (1/n) R2/3 S1/2, R represents the __________ of the watershed.
In the formula V = (1/n) R2/3 S1/2, R represents the __________ of the watershed.
Flashcards
Design Rainfall Intensity (I)
Design Rainfall Intensity (I)
The total amount of rainfall divided by the time period it falls, measured in millimeters per hour.
Rainfall-Runoff Analysis
Rainfall-Runoff Analysis
The process of calculating how much water flows over land as a result of rainfall.
Rational Method
Rational Method
A method used to estimate the peak runoff rate from a small watershed due to rainfall, assuming that the rainfall intensity is constant.
Watershed
Watershed
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Intensity-Duration-Frequency (IDF) Chart
Intensity-Duration-Frequency (IDF) Chart
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Time of Concentration (Tc)
Time of Concentration (Tc)
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Overland Flow Time (To)
Overland Flow Time (To)
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Travel Time through Channels and Pipes (Tch)
Travel Time through Channels and Pipes (Tch)
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Manning's Equation
Manning's Equation
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Return Period
Return Period
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Rainfall Intensity
Rainfall Intensity
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Rainfall Duration
Rainfall Duration
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SCS Curve Number Method
SCS Curve Number Method
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Curve Number (CN)
Curve Number (CN)
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Runoff Coefficient (c)
Runoff Coefficient (c)
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Residential (c)
Residential (c)
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Industrial (c)
Industrial (c)
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Open Spaces (c)
Open Spaces (c)
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Water/Pond (c)
Water/Pond (c)
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Study Notes
Watershed Concepts
- A watershed is a contiguous area where rainfall or runoff drains to a common outlet.
- Basin, watershed, and catchment are synonymous terms for a geographical area.
- Surface runoff is the portion of precipitation that runs over the land surface and not into the soil.
Rainfall-Runoff Analysis
-
Rational Method: A simple method for estimating peak flow, Qp = CiA, where:
- C = runoff coefficient (based on land use)
- i = rainfall intensity (for a duration equal to time of concentration)
- A = watershed area
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Time of Concentration (Tc): Time for water to travel from the most distant point in the watershed to the outlet. Methods for estimating Tc include:
- Kirpich equation
- Izzard equation
- Kerby-Hathaway equation
- FAA English & SI methods
- Van Sickle.
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SCS Velocity Method: Estimating concentration time by total travel time calculated by dividing into segments.
SCS Curve Number Method
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SCS Curve Number (CN) method estimates direct runoff from rainfall.
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The CN is calculated based on soil characteristics, land cover, and antecedent moisture conditions
- S = 25400/CN - 254 (millimeters). Other calculations may use inches.
- Ia=0.2S
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Rainfall-runoff relationships are based on empirical observations.
-
Composite Runoff Coefficient: A method for calculating a single CN for watersheds with diverse land use types.
- Weighted averaging, using area proportions of each land use category.
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Description
This quiz covers key concepts in watershed management, including definitions, runoff analysis methods, and time of concentration calculations. You'll explore various methods for estimating peak flow and travel time within a watershed, focusing on practical applications and formulas. Test your knowledge on watershed dynamics and analysis techniques.
