Instructor Materials: Overview of the Modeling Flood Hazards module
Students will: Summative Assessment
Unit 5 is the summative assessment. It provides data sets for students to apply concepts learned in prior units to a new site. It is beneficial to tell students about the Unit 5 assignment early in the module so that they know they are going to be asked to apply the skills they are learning independently. Learn more about assessing student learning in this module.
The module covers material sequentially, but the units can also often be taught as stand-alone lessons. For instructors who do not wish to use the module in its entirety, suggested pairings are included in the "Context for Use" section on each unit's page. If you plan to use Unit 4 and 5, you should plan ahead to make sure that HEC-RAS (Hydrologic Engineering Center's River Analysis System) software for generating flood maps is ready to use. The software is free but it only works on Windows 64-bit computers. If your school has a computer lab, arrange to have the software added to lab computers. If you are relying on student computers, you will need to dedicate time to making sure that each student (or student group) has a functional version. If a large percentage of students have Mac computers, you can point them to resources that allow the software to run cross-platform. See Unit 4 for more advice.
In this unit, students are introduced to the concept of flooding and the mechanisms that cause different types of floods in natural and urban environments. Students will interpret annual maximum flow series to relate the magnitude of past flow events to their frequency. Students will explore different datasets to describe the magnitude of a flood, its spatial extent in the form of a map, and its socio/economic impacts.
This unit introduces students to the statistical concepts that are used to determine the relationships between peak flow magnitude, return periods, and societal risk. The intent is that when a student hears or uses the term "100-year flood," they understand how it is obtained. The vocabulary and techniques of flood frequency analysis (FFA) are introduced through demonstrations. In a formative assessment exercise, students will use concepts learned in demonstrations to conduct an FFA in a new river.
Streamflow becomes a flood when water overflows its channel banks. The shape and characteristics of a stream channel and its adjoining floodplain are therefore essential components of defining and appraising floods. In this unit, students evaluate the geometry of river channels and floodplains using LIDAR-derived data and compute the depths and velocities of flow rates within channels using Manning's equation.
The flow or discharge value in a river does not mean much to a lay person or a decision maker because this flow can be insignificant on a big river or can be dangerous on a small creek. Thus, we must know how to translate this flow value into the water depth, velocity, and the corresponding extent to understand its impact. The objective of this unit is to perform hydraulic modeling on a reach of Wabash River near Lafayette, Indiana, to estimate water surface elevation and extent corresponding to a 100 year flow. Students will learn the basics of hydraulic modeling using HEC-RAS to simulate the flow hydraulics using one-dimensional steady state assumption. The outcome will be the inundation extent corresponding to the 100-year event along the reach of the Wabash River near Lafayette, IN. Make sure you have HEC-RAS available on school or personal computers prior to the start of the unit. See unit page for more information.
Most often we characterize floods based on their return periods. Considering new land developments and the changing climate, what was once a 100-year flood may change over time. Thus, if we are going to experience the previously defined 100-year flood more frequently, the new 100-year flood may be what was a 500-year flood before. One may then wonder what will be the impact of this 500-year flood compared to a 100-year flood? Is it five times bigger and more damaging than a 100-year flood? The goal of this Unit is to have students quantify floods for 100 and 500 year return periods, and map the corresponding flood inundation extents. The students will then use these results to see how the flood magnitude and the inundation area changes for these floods. The final inundation maps can also be used to estimate key infrastructure that may be vulnerable.
This unit serves as the Summative Assessment for the module. Data sets are provided for students to apply concepts learned in prior units to a new scenario. This unit also uses HEC-RAS, but can be done by students largely outside of class time.
Making the Module Work
To adapt all or part of the module for your classroom you will also want to read through