Module 4: Understanding Sea-Level Change
The goal of Module 4, Understanding Sea-Level Change, is to provide students with the framework for understanding how sea-level changes over geological time scales. Upon completion of the module, students will be able to:
- Develop fundamental geospatial (linking geography and geology) skills and concepts needed to assess coastal processes that produce sea-level change;
- Explain what sea level is and differentiate the mechanisms that interact to produce changes in sea level over short-term and long-term time periods;
- Characterize trends in sea level over geologic time and conceptualize how changes in sea level can result in various spatial scales of coastline change; and
- Use real tidal gauge data from diverse global regions to identify recent trends in sea-level change and use these trends to formulate reasonable projections for future sea-level positions.
Context for Use
Description and Teaching Materials
In this module, students will complete two activities. The formative assessment requires students to use the "The Interactive Earth" website to visualize how tides and other processes can produce sea-level change over different scales of space and time, as well as the "Sea-Level Rise Visualization for Alabama, Mississippi, and Florida" tool produced by the United States Geological Survey (USGS). In the former, students will need to change a variety of parameters including tidal characteristics, storm impacts, and lunar phase effects, so they can analyze how each factor changes the extent of coastal flooding as a result of short-term and long-term sea-level change. In the later, which is a GIS-based visualization system built from topographic data and sea-level measurements from Hurricane Katrina, students will explore the impact of projected sea-level rise on the Gulf Coast and will be able to compare it to actual water levels produced by Katrina. Students will then complete a series of multiple-choice questions designed to assess their ability to interpret and analyze what they have observed.
The summative assessment is a bit more involved and requires students to pull data from a global database on historic sea-level readings (i.e. tide gauge data). The data is obtained from the Permanent Service for Mean Sea Level. Students will self-select at least two different locations with as long a record as possible (i.e. at least 30 years preferred). They will then visualize the sea-level data (on the web) to determine its relative completeness, and if their data is relatively complete for the lifetime of the recording station, then they will download the data into Excel. In Excel, students will clean up and label the data, perform calibration calculations to mean sea level, and plot sea- level curves so they can assess trends in sea level bothâ€”on short-term and over long-term time increments. Finally, students will project a linear sea-level trend into the future (i.e. using Excel forecast function) to approximate the position of sea level. Student will be able to then consider local geology and tectonic setting as it pertains to whether their data shows evidence of sea-level rise, or sea-level fall.
Materials for students for this module are located at the link below. Teachers can find documentation of the activities at this location as well as rubrics for students. Rubrics for teachers are compiled under Assessment on this site. Suggestions for teaching and a list of the assessments are found below.
Teaching Notes and Tips
Optional or extra components
Students are encouraged to explore another user-friendly GIS-based visualization tool to explore other regions of the United States. The tool is called the Sea-Level Rise and Coastal Flooding Impacts Viewer which is to be found on NOAA's Digital Coast website. Three additional open-ended questions for students to explore are provided. These focus on evaluating specific regions of their interest to investigate potential impacts of sea-level rise on human landscape elements, interior waterways, and natural environments that serve important ecosystem services.
Strategies for completing the module
A number of learning checkpoints are developed immediately following major sections of the module. They are designed to make sure students take some time to consider what they have read and check for their understanding. As Module 4 covers, in detail, the numerous intrinsic, extrinsic, and anthropogenic reasons for se-level change, and the various timescales that sea level can change, this module's content is foundational to the rest of the course. Thus, students should be encouraged to take advantage of all of the learning checkpoints, and wherever possible, instructors could ask students to reflect on these as part of discussions, blog posts, or for other active learning sessions.
Suggestions for instruction delivery
Due to the in-depth readings for this module, it is recommended that the instructor take time prior to initiating the summative assessment to review patterns of sea-level change over different timescales and their causes. Students had questions about intrinsic versus extrinsic variables and raised questions about how human activities can exacerbate natural processes. It was helpful for students to put into context modern sea-level trends with regard to historic sea levels and the rates and ranges of natural sea-level change. Students also had questions about proxy data sets (ice cores and stable isotopic data), and this allowed for good class discussion prior to working on their own data sets collected from the PSMSL website.
What works best for the module?
First, students should be encouraged to explore the extra links, maps, videos, and other information that is provided within the text of the modules. Students who read all of the material and follow the extra, external links will develop the most complete understanding of concepts.
Students should be encouraged to use the hands-on, active learning links and should carefully read the content of the module before coming to the face-to-face meeting/lab time. Students should be encouraged to do the reading over the weekend prior to class the upcoming week, and should dedicate some time every day, or at least every other day, to staying on topic and on task. Students should also review the assessments, and if possible, start them so they come to class to work efficiently.
Completing the formative assessments was generally uneventful for students, as long as students read and carefully followed the step-by-step directions. In class, students should be encouraged to work in pairs or small groups to help with their interpretation/critical reasoning process as they work on individual questions. Students can then ask the instructor for guidance when necessary.
The summative assessment requires scaffolding, especially for first-year students. Upper-level students will find it less challenging because they have likely used Excel in some capacity to graph and plot data. Thus it is best delivered in two instructional phases. Phase one focuses on accessing, downloading, and preparing the data for analysis; this could be completed independently (see below) and does not necessarily require the formative assessment. A teaching assistant, if available, can help students with some of their individual challenges. Experience in the test showed that new students had more difficulty with Excel. Phase two focuses on plotting the data using Excel and interpreting the data using critical reasoning and using background knowledge from earlier modules and the formative assessment. Depending on instruction modality, the instructor may want to require students to follow the detailed step-by-step instructions that are provided for phase one. The "cookbook"-style instructions are clear for the most recent version of Microsoft and PC/Mac platforms. Older versions may have some minor problems, therefore having a teaching assistant or an upper-class student available to help is recommended. Regardless, all students should be able to work on their own prior to class time if necessary to increase efficiency. Class time should be used to help students with very specific questions, but more importantly, face-to-face time can be used to move students from the seeing tide gauge data as abstractions of columns and rows of numbers to a level of understanding where they visualize and interpret the meaning of the data in concrete ways. Again, it is wise to pair students in the class to think about and share their data and any challenges. If students are not prepared for class, these students should not be allowed to disrupt the learning process for other students. Various course management strategies can be implemented to minimize ill-prepared students.
With regard to the summative assessment, depending on modality of instruction, completing plots for three different locations can consume in-class time (especially in the once per week implementation). Therefore, you may opt to provide a portion of a data set (already in Excel) and representative plots for one or two sites as models for your students. Thus students would simply add one or maybe two sites of their own choosing and move the process forward faster. If it is important for students to learn data processing skills in your course, repetition of procedures is usually an effective strategy; however, if time is a limiting factor, simplifying the process by reducing the number of sites is a time-saving solution. One recommendation is to poll students (upon completion of their graphs) by raise of hands. Ask them "How many of you found one location with evidence of sea-level rise?" Then "How many of you found two locations with sea-level rise?" ... "How many of you found all three locations that have sea-level rise?" Then go to "How many had a site with evidence of long-term sea-level fall?," "How many with two sites of long-term sea-level fall?" and so on. In both of my class sections, the vast majority of students had two or three sites with evidence of sea-level rise. Only one or two students had two sites with long-term sea-level fall. It was quite revealing for the students to see so many hands go up for sea- level rise, and so few go up with sea-level fall. I then asked students who had one or two sites with falling sea-level trends over time to give their locations. I then visited a couple of these sites in Google Earth, and we explored the geography of each region. Students were asked to explain why we might have different trajectories, and this promoted great discussion. In most cases, students would provide answers like "ground is rising because of tectonics" or "the site was near glaciers so the ground is bouncing back," etc. These answers re-enforced learning from earlier modules.
What students found tough and how we adapted:
Students who did not thoroughly read the text and look at the accompanying external links had the most problems with the module. These students were unable to relate concepts to one another and consequently had difficulties completing some of the assessments.
As mentioned previously, delivery modality and face-to-face instructional time is critical for the learning process. Students who engage the material daily, or at least every other day, were far more likely to complete projects with less difficulty and with better individual outcomes. Students who came to class ill-prepared to work experienced the most difficulty on both the formative as well as the summative assessments. Although this module was one of the most time-intensive modules, it was also well received by many students and provided a number of very good in-class discussions.
In terms of adaptations, see above for some of the potential options. PSU and UNO chose to modify this assignment by reducing the number of plots to be produced to better allow students to achieve the primary learning objectives.
There are two parts to the formative assessment, Recognizing Short- & Long-Term Sea-Level Change, to be completed, both of which will help students think about important key concepts and move them from abstract understanding of the concepts to applying them through interpretation of map-based visualizations. The formative assessments in this case are not required to initiate the summative assessment, but critical analysis of the summative will require that students complete the formative assessments.
- Formative Assessment Part 1: Interactive Earth asks the students to work with visualization tools to evaluate models of short- and long-term sea-level change in the form of tides, storm surge, and longer-term sea-level rise. Students will be able to toggle different scenarios and evaluate spatio-temporal implications of different parameters of the coastline and various physical parameters. Students will then complete three multiple-choice/ranking questions to demonstrate their abilities to apply critical concepts.
- Formative Assessment Part 2: Sea-Level Rise for Alabama, Mississippi, and Florida focuses on the use of a GIS-based data visualization tool to explore the real impact (spatial range) of Hurricane Katrina's storm surge, and various sea-level rise scenarios from 1 to 6 feet. Students will interact with different base maps (satellite imagery, street maps, and terrain or topographic maps), and population distribution maps to make assessments about the real and potential impacts of short- and long-term sea-level rise along the entire Gulf Coast region, and particularly on the Biloxi, Mississippi, region. Students complete nine multiple-choice questions.
The summative assessment, Tide Gauge Data, was designed to 1) help students learn how to access, plot, and analyze archival instrumental tide gauge data sets that they select from disparate regions around the globe, and 2) allow students to self-assess how sea level is changing regionally and globally. Through this assessment, students develop individual data analysis skills, but more importantly, they contribute to class learning outcomes by sharing their individual findings. Students' understanding of sea-level change can thus be developed through their own logic when presented with clear class aggregate data that show an overwhelming number of sites that show clear evidence of sea-level rise. Moreover, given the learning outcomes focused on understanding coastal geology in Unit 1 (Modules 2 and 3), students should have the background information to assess the geologic settings of their selected tide gauging station in order to better interpret why some sites show asynchronous sea-level fall.
Finally, completion of the summative assessment for this module is critical as the data and sea-level plots were used for completion of the final project for the course. This needs to be stressed so students work carefully on this assessment.
References and Resources
- Student readings are provided in Student Materials — Module 4: Understanding Sea-Level Change.