Problem Statement

This module is focused on understanding Runoff generation during extreme weather events, using Hurricane Helene as a case study. It explores how intense rainfall interacts with different components of the landscape particularly the soil, to influence the movement of water across and beneath the surface. The primary goal is to examine the hydrological processes that control how precipitation is divided into infiltration, surface runoff, and subsurface flow during such high-impact events. The role of soil properties, which significantly shape the watershed’s response to heavy rainfall have been explained. Key factors such as soil texture, type, saturation levels, and infiltration capacity determine how much water is absorbed into the ground versus how much becomes overland flow. For example, well-drained sandy soils tend to absorb more water and delay runoff, while compacted or clayey soils often lead to quicker and more pronounced runoff due to limited infiltration. Through this module, hydrologist and practitioners will learn how to quantify and compare rainfall, infiltration, and runoff volume under different soil conditions. The outcomes of this module is to calculate the runoff, while also providing a scientific basis for sustainable watershed management.

Module Overview

This module aims to explore the hydrological dynamics of Hurricane Helene, with a focus on runoff generation, and watershed response following the storm event. It addresses the question: How does rainfall translate into streamflow during extreme events, and what factors control this response? To answer this, learners will examine key factors such as soil properties,and antecedent moisture conditions, which influence water movement through a watershed. As part of the technical component of the module, learner will implement the Green-Ampt infiltration model, a physically based method used to estimate runoff based on rainfall intensity, soil infiltration capacity, and hydraulic properties. By quantifying these parameters, the module provides a foundation for understanding how different landscapes respond to extreme precipitation, and how this knowledge can be applied to improve flood forecasting, watershed modeling, and the design of flood protection infrastructure Target Audience Operational Hydrologist Tools Needed Computer with access to Internet, Excel, Jupyter Notebook Suggested Implementation Mode The intent of this module is to bring together different concepts and techniques typically covered in hydrology courses using a real-world case study with an actual hydrologic problem on flood protection. The design of the module is such that hydrologist should be able to complete all activities on their own and each activity has its own worksheet for analyzing the progress and knowledge acquired from the module. Expected Completion Time One to two weeks is a reasonable timeframe to complete the entire module. Course Adaptation This course was adapted from HydroLearn411: "Quantifying Runoff Generation" This course is available for adaptation and customization by other instructors. You can request a link to download a copy of the course and import it back into your own new HydroLearn course.