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Homework Help: Lag time in hydrograph

  1. Dec 8, 2017 #1
    1. The problem statement, all variables and given/known data
    Lag time in hydrograph means teh time of center of rainfall to center of hydrograph , according to my book .

    2. Relevant equations

    3. The attempt at a solution
    Since lag time can be understood by the time taken for the water to reach river , contributing to max discharge ... So , i think in photo 755 , it's wrongly labelled , it sjould be labelled in the beginning of the graph , which is the green line , correct me if i am wrong.

    Attached Files:

    • 754.PNG
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    • 755.png
      File size:
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  2. jcsd
  3. Dec 9, 2017 #2


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    Staff: Mentor

    I'm not understanding your question. is point "A" the center of the rainfall?
  4. Jan 24, 2018 #3


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    Gold Member

    Not my field but...

    I don't think figure 6.5 is being used to define N. They quote a value of N for a typical "natural basin".

    It appears they are just using N to estimate where on the graph the Direct Run Off (eg from a rain shower) ends and the flow returns to the base line flow (which itself is changing).
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