What is the significance of lag time in a hydrograph?

[tzx9633]

Homework Statement

Lag time in hydrograph means the time of center of rainfall to center of hydrograph , according to my book .

Homework Equations

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.

 

[berkeman]

I'm not understanding your question. is point "A" the center of the rainfall?

 

[CWatters]

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).