26.5.1 - φ-Index (Phi Index)
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Practice Questions
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Define φ-Index in hydrology.
💡 Hint: Think about how water movement into the soil is measured.
Explain the application of the φ-Index in the Rational Method.
💡 Hint: Consider how runoff relates to infiltration rates.
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Interactive Quizzes
Quick quizzes to reinforce your learning
What does the φ-Index measure?
💡 Hint: Think about its role in hydrology.
True or False: The φ-Index is variable throughout a storm event.
💡 Hint: Consider how we use it in calculations.
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Challenge Problems
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A region experiences varying φ-Index values during different seasons (winter 10mm/hr, summer 25mm/hr). If a storm delivers 50mm of rain, calculate how much runoff occurs in both seasons if the rainfall intensity is 15mm/hr.
💡 Hint: Calculate the difference between rainfall and φ-Index for both cases.
During a storm, if the φ-Index is 12mm/hr and rainfall is 36mm/hr for three hours, determine the total runoff.
💡 Hint: Keep track of time and the difference in rates.
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