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Basin Lag Formula:
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Basin Lag is the elapsed time between the occurrences of the centroids of the effective rainfall. It represents the time delay between rainfall and peak runoff in a watershed.
The calculator uses the Basin Lag formula:
Where:
Explanation: The formula calculates the basin lag by subtracting half of the effective rainfall duration from the time of peak discharge.
Details: Accurate basin lag calculation is crucial for hydrological modeling, flood forecasting, and watershed management. It helps in predicting the timing of peak flows and designing appropriate drainage systems.
Tips: Enter Time of Peak and Standard Duration of Effective Rainfall in seconds. Both values must be positive numbers greater than zero.
Q1: What is the relationship between basin lag and time of peak?
A: Basin lag represents the time delay from the centroid of effective rainfall to the peak discharge, while time of peak is the total time from rainfall start to peak discharge.
Q2: How does effective rainfall duration affect basin lag?
A: Longer effective rainfall durations typically result in longer basin lags as it takes more time for the water to travel through the watershed.
Q3: What factors influence basin lag in a watershed?
A: Watershed size, slope, land use, soil type, and channel characteristics all influence the basin lag time.
Q4: Why is basin lag important in flood forecasting?
A: Basin lag helps predict when peak flows will occur after a rainfall event, which is critical for flood warning systems and emergency response planning.
Q5: Can this formula be used for all watershed types?
A: While this formula provides a general approach, specific watershed characteristics may require adjustments or different calculation methods for optimal accuracy.