GETSI Teaching Materials >Flood Hazards > Unit 1: Introduction to Flooding
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This module is part of a growing collection of classroom-tested materials developed by GETSI. The materials engage students in understanding the earth system as it intertwines with key societal issues. The collection is freely available and ready to be adapted by undergraduate educators across a range of courses including: general education or majors courses in Earth-focused disciplines such as geoscience or environmental science, social science, engineering, and other sciences, as well as courses for interdisciplinary programs.
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Unit 1: Introduction to Flooding

Venkatesh Merwade, Purdue University (
James McNamara, Boise State University (


Do geoscientists understand the meaning of floods and their role within the broader context of ecological and societal impacts? In this unit, students are introduced to the concept of flooding and the mechanisms that cause different types of floods in natural and urban environment. 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 flood, its spatial extent in the form of a map and its socio/economic impacts.

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Learning Goals

Unit 1 Learning Outcomes

Students will be able to:

  • Explain the meaning of annual maximum series of streamflow and its role in flood hazard analyses
  • Estimate return period or frequency associated with a specific flow magnitude
  • Compile data related to historic floods and assess the socio-economic impacts of the flooding event on the surrounding communities
  • Create graphs and maps using time series and geospatial data

Unit 1 Teaching Objectives

  • Affective: Provides students with the opportunity to assess and understand the impact of flood hazards on humans and the natural environment
  • Behavioral: Promotes students' skills to use streamflow data and conduct basic flood frequency analysis. Promotes students' skills to use Excel and ArcMap/Google Earth
  • Cognitive: Facilitates students' ability to interpret streamflow data for identifying historical floods

Context for Use

The content of Unit 1 is appropriate for advanced geoscience, earth science, and civil engineering courses at the junior and/or senior level, in which the basic hydrologic cycle and related processes are taught. This unit uses streamflow data and a little bit of statistics, so it is appropriate to present this material in either the third or fourth quarter of the course, when students have grasped the basics of hydrology and hydrograph analysis. Unit 1 provides students with basic knowledge of flooding, its causes, and management strategies. Students are also exposed to some of the terminology used in professional practice related to flood hazards, such as return period, design flow, and flood frequency. Unit 1 provides a broader perspective of a flood hazard, its estimation, and its impacts. It can be used as a standalone teaching/learning unit to introduce students to the basics of flood hazards. If the entire module is used, Unit 1 provides the motivation for students to do the rest of the units, where the specifics of flood hazard estimation and its mapping are covered in more detail. If students had exposure with basic probability and statistics, this unit can be done much earlier during the semester, such that the module can be spanned out over a longer duration of time.

Description and Teaching Materials

This Unit is divided into three parts. The description of each part is given below. This unit may be introduced during a lecture using the PowerPoint presentation, and the subsequent parts done as homework. If homework is not the preferred way, subsequent parts can also be performed in either a computer laboratory or flipped classroom environment, where each group of students works together with help or guidance from the instructor. Unit 1 introduces students to the broader concept of flooding, its different types, the relationship between flood magnitude and frequency, and some of the management strategies for handling flood hazards. Students are exposed to the different types of data that can be used to identify historical flood events, compute return periods associated with different historical flow values, and finally, map the 100-year flood hazard area. Students will learn how to get some of these basic data and plot or map them using standard softwares such as MS Excel, ArcMap, and Google Earth. If the students are not familiar with Excel, ArcMap, or Google Earth, introductory tutorials on how to download and plot gauge data in Excel and how to create a flood map in ArcMap or Google Earth are provided in the teaching materials section.

Part A - Peak flow and return period

Students compare data and site parameters such as climate (especially precipitation) between two gauging stations -- one in Illinois and one in Indiana. They look at peak flows and calculate recurrence of 6000 cfs and 15,000 cfs flows. You can choose to have the students access the data portals and download the data directly using the provided tutorial (below) OR you can provide them with a spreadsheet of the flow data (below). They will search online for information on topography, geography, and climate of the two sites.

Part B - Assessing flood hazard

Students pull together data, including information about the gauging site, daily and annual maximum flows, and a FEMA flood map. Part B of this unit can be done mostly outside of a classroom setting, but it would be good to devote some classroom time to form groups, set expectations, and answer any questions related to the activity. Divide the class into groups with four to six students in each group. Each group is then assigned (randomly or any other way deemed appropriate) an area of study from the following list:

  • Area 1: Boulder County, Colorado (Gauge 1: 06730200 Boulder Creek at North 75th St. near Boulder, CO)
  • Area 2: Fort Bend County, Texas (Gauge 1: 08116650 Brazos River near Rosharon, TX; Gauge 2: 08114000 Brazos River at Richmond, TX)
  • Area 3: Frederick County, Maryland (Gauge 1: 01619500 Antietam Creek near Sharpsburg, MD; Gauge 2: 01643000 Monocacy River near Frederick, MD)
  • Area 4: Kalamazoo County, Michigan (Gauge 1: 04106000 Kalamazoo River at Comstock, MI; Gauge 2: 04105500 Kalamazoo River near Battle Creek, MI)
  • Area 5: White County, Indiana (Gauge 1: 04101000 St. Joseph River at Elkhart, IN; Gauge 2: 03332555 Tippecanoe River at Norway, IN; Gauge 3: 03333050 Tippecanoe River near Delphi, IN; Gauge 4: 03332605 Tippecanoe River below Oakdale Dam, IN)

The above list includes areas that have experienced major flooding since 2000, and represent different geographic, climate and socio-economic settings. An important data resource: the number and name of the United States Geological Survey (USGS) stream gauge(s) for each location is also provided. Each group will then perform a simple flood hazard assessment for their area by using different datasets. Before assigning the flood hazard assessment task to the students, the instructor should study the example of a flood hazard analysis provided and/or explore the data sources. Additionally, the instructor should advise students to be fair in assigning the workload among themselves. A sample workload example for each member in a group of six students is provided in the Teaching Materials section. It may help students within a group to pick roles depending on their skills.

The flood hazard assessment will include the following:

  1. Obtaining historical daily and annual maximum series for the USGS gauge to see how many times this area has been flooded since the date has been recorded. Instructions (Tutorial for downloading and plotting daily/annual peak series) on getting the daily and annual maximum series is included in the teaching material section, and should be provided to students. The flood stage for each station is usually provided on USGS graphs. If not, it can be obtained from the corresponding National Weather Service Advanced Hydrologic Prediction Service. The students will have to zoom to the station on the AHPS website, and then click to see a graph for the station which also shows the flood stage. This plot shows the flood/action stage on one axis and the corresponding discharge on the other axis. Use this discharge value as reference for the USGS annual maximum series in finding the number of times this gauge has been flooded.
  2. Pick the most recent major flood for this area and find its return period. This can either be done through quantitative analysis as described in Part A or can be obtained from news reports.
  3. Get the FEMA flood hazard map for this area and display it using either ArcMap or Google Earth. Instructions on creating this map are provided in the Teaching Materials section.
  4. Get any data or information on the damages from this recent flood. This can be done via online search or through published news reports.
  5. Do some online research on the area to see if any flood management strategy has been implemented or being implemented. Use the four strategies as outlined in the FEMA document/presentation.
  6. Discuss any potential flood management plan for the community to minimize the damages from future floods.
  7. Prepare a presentation, maximum 10 slides, summarizing the flood hazard assessment for the selected area.

Part C - Presenting findings

Part C involves presentation from each student group and reflection on what they have learned. From these presentations, students will learn how the flood hazard and its impacts vary among the different sites and the factors that contribute to these differences.

Teaching Materials and Resources

Teaching Notes and Tips

  • If the students end up using Google Earth, some good general Google Earth tutorials for both the instructor and the student are available.
  • If the class has both graduate and undergraduate students, the instructor may form groups such that there is one graduate student in each group to lead the group activity.
  • The latter part of the PowerPoint with management strategies has a lot of text. That text can also be converted to handout to save presentation time.
  • With the group activity, it is advisable to have all students look at and approve the presentation before submitting it to the instructor so they know each of them "own" it, and the entire group is accountable for mistakes made by one or more members in the group.
  • Even though FEMA has a flood map for Area 3 (Frederick county) on their website, the students found out that the map delivered is for a neighboring county. We will try to fix this by contacting FEMA. For the purposes of students' learning, it is okay to include this map in their presentation.


Formative Assessment

Observation of student activity and conversations, individual questioning, and group discussion are excellent ways to conduct formative assessment as the students complete this unit.

Summative Assessment

The student-made presentation and/or the student exercise forms the summative assessment for this unit. The first two parts in the student exercise have definite quantitative answers, The third question is reflection of their broader understanding of the subject and the cause-effect relationships between the different factors that are related to the flood risk. To receive full credit, students must show their work, where appropriate. Students work can be assessed by using the provided rubric.

Unit 1 Student Exercise and Presentation Rubric (Microsoft Word 2007 (.docx) 14kB Mar13 23)

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This module is part of a growing collection of classroom-tested materials developed by GETSI. The materials engage students in understanding the earth system as it intertwines with key societal issues. The collection is freely available and ready to be adapted by undergraduate educators across a range of courses including: general education or majors courses in Earth-focused disciplines such as geoscience or environmental science, social science, engineering, and other sciences, as well as courses for interdisciplinary programs.
Explore the Collection »