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

579 views
April 19, 2022
by
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.

## Key Insights

• 🇦🇪 Unit hydrographs are graphical representations of the relationship between rainfall and runoff.
• 🇦🇪 Converting unit hydrographs for different storm durations involves lagging the hydrographs and dividing the resulting ordinates by the total effective rainfall depth.
• 📁 Direct runoff hydrographs can be obtained by multiplying unit hydrograph ordinates by the effective rainfall depth.
• 📁 The resulting direct runoff hydrographs can be combined to calculate the direct runoff hydrograph for longer storm durations.

## Transcript

hello everyone in this video we are going to solve numericals based upon the derivation of the unit hydrograph from the given unit hydrograph so let's start so the first problem it says that convert a two hour unit hydrograph to a six hour unit hydrograph for the given discharge values so at the different durations of the time the discharge values ... Read More

### 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.