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Comparison of Two Commonly-Used Methods for Quantifying Runoff


Problem Statement

A common application of hydrology is to apply rainfall and geographic data to design flood protection infrastructure to protect people and property from the impacts of flash flooding. Two important questions related to the design of flood protection infrastructure are:

1. How much streamflow occurs in a river in response to a given amount of rainfall?

Answering this question requires us to know where water goes when it rains, how long water resides in a watershed, and what pathway does it take to the stream channel.

2. Which method is most appropriate for computing the amount of streamflow?

This question requires us to choose between various methods based on several factors including: data requirements, data availability, required output(s), and the inherent strengths and limitations of each method.

This module addresses these questions by examining two commonly-encountered approaches: Green-Ampt and SCS (Soil Conversation Service) curve numbers. As you work through the module and compute the amount of runoff generated from a rainfall event, you will not only learn the details of each approach and how each method is implemented, but you will also gain valuable insight as to the strengths and limitations of each.

Course Author

Peter Rogers, PhD, PE

Georgia Southern University. Contact:

Target Audience

Junior/Senior Hydrology and Water Resources Engineering Courses

Tools Needed

Computer with access to Internet, Excel, and free HEC-HMS software