# Numerical Based on Derivation of Unit Hydrograph from Given Unit Hydrograph - Hydrology | Summary and Q&A

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April 19, 2022
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Ekeeda
Numerical Based on Derivation of Unit Hydrograph from Given Unit Hydrograph - Hydrology

## TL;DR

Learn how to convert a two-hour unit hydrograph to a six-hour unit hydrograph and compute direct runoff hydrographs and unit hydrographs for different storm durations.

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### Q: How do you convert a two-hour unit hydrograph to a six-hour unit hydrograph?

To convert a two-hour unit hydrograph to a six-hour unit hydrograph, you assume another two-hour rainfall event with the same rainfall depth. The resulting three two-hour unit hydrographs are combined to form the six-hour unit hydrograph.

### Q: How do you calculate the direct runoff hydrograph from a unit hydrograph?

To calculate the direct runoff hydrograph from a unit hydrograph, you multiply the ordinates of the unit hydrograph by the effective rainfall depth for each time interval. The resulting values represent the direct runoff discharges.

### Q: How do you calculate the 12-hour unit hydrograph from two different storm events?

To calculate the 12-hour unit hydrograph from two different storm events, you add the corresponding ordinates of the direct runoff hydrographs for each storm. The resulting values represent the 12-hour direct runoff hydrograph. Dividing these values by the total effective rainfall depth gives the 12-hour unit hydrograph.

### Q: What is the significance of the peak discharge in a unit hydrograph?

The peak discharge in a unit hydrograph represents the maximum rate of flow for a given storm duration. It is an important parameter for estimating flood volumes and analyzing the response of a catchment to rainfall.

## Summary & Key Takeaways

• The video explains how to convert a two-hour unit hydrograph to a six-hour unit hydrograph by assuming another two-hour rainfall event.

• It demonstrates the process of obtaining direct runoff hydrographs and unit hydrographs for storms with rainfall excess values of 3 centimeters and 2 centimeters.

• The video discusses the calculation and interpretation of discharge values for different storm durations and how to convert them into unit hydrographs.