Unit 7.1 - Model My Watershed

Students will be able to:

• Describe a watershed and delineate a watershed on a map;
• Identify the key factors in a watershed that impact runoff and sediment yield, describe how increased storm-water runoff affects landscapes (e.g., erosion, channel incision, sedimentation) and describe how those factors are impacted by human development;
• Evaluate the impact of human alterations to the landscape and investigate how best-management practices can lessen those impacts;
• Compare social and economic impacts to society from both runoff changes and from mitigation measures;
• Analyze how neighborhood redevelopment can affect local communities, to their benefit and/or to their detriment.

This unit uses a web application called Model My Watershed. It is an interactive, online hydrologic modeling tool that allows users to calculate water budgets for various storm intensities, generic land-cover types, and soil textures for a generic patch of land ("Micro model") or for an area you have defined in your own watershed ("Watershed model"). Its purpose is to investigate various water management best practices in urban/suburban neighborhoods. (It's not very effective in Western states away from urban areas). Students will be asked to research various best management practices (BMPs) and develop a report on the appropriate use of these measures. Finally, students will select locations on their campus where they will develop designs using BMPs, to address problematic areas where runoff produces problems. Individual students or teams will report back to the class on their designs, both orally and using a handout for the class to use for discussion purposes. This module is appropriate for a variety of science majors wishing to learn more about Human Interactions and Critical Zone science.

Getting Started

Faculty should use the "Generic Model" to introduce basic hydrologic concepts. It allows for students to change three variables (rainfall amount, land cover, and soil texture). This model provides a basic introduction of how those three primary variables affect the partitioning of rainfall among other water cycle components on a land surface. Because it is not site specific, slope is not considered in this model, although it is included in the GIS-based modeling.

One of the first learning outcomes to address is defining what a watershed is and how to delineate it. SERC has a great video of watershed delineation that will be useful (link below). If you feel that students need to cover this in more detail, there is also a great watershed delineation unit on the SERC site (link below). However, since this course is aimed at upper-level geoscience or biology majors, it may not be necessary to spend much class time on this.

Unit 7.1 - Day 1 (75 min total)

Watershed Modeling (25 min)

• Review Water Balance Equation: Ppt = ET + Runoff + Infiltration
• Review function of Daily Water Budget using:
• Micro Site Model
• Review Watershed Delineation
• Watershed Delineation Animation - Simple
• Watershed Visualization - Verde River

• Activity - Assignment Overview (10 min) - what to do and tips for running the model.
• Preview the material found at Model My Watershed - about
• Play around with the Micro Site Model to get a feeling for the effect of land cover and soil on the water budget

The following two options ask students to explore the relationship between runoff and land cover type or management practice. A discussion about validating and testing their hypothetical scenarios, particularly using the simple model in Option A, might prove interesting. The limitations of each technique should also be considered.

Option A - Model my Watershed

• Activity - Use "Model My Watershed" to investigate the water budget and water quality of your site (40 min)

• Launch the Model My Watershed App (either login as a User or a Guest)
• Zoom into some area of interest;
• For rural watershed-scale areas, turn on HUC-12 Watershed boundaries using "Select by Boundaries".
• For smaller urban areas, use "Draw Area" to define your area of interest.
• Analyze Tab contains:
• Land Tab - Bar chart of % Landcover
• Soil Tab - Bar chart of % Soil infiltration capacity
• Animals Tab - Farm census for your area
• Point Sources (if any) from EPA NPDES (National Pollutant Discharge Elimination System)
• Water Quality - Delaware River Basin only
• Model tab (Site Storm Model (with precipitation controlled by slider) or Watershed Multi-year (annual) Model
• Runoff/Hydrology tab - Water budget components: graphs (above), table (below)
• Water Quality tab - Water Quality component tables: Landcover source zone (above), TMDL (below)
• Do these make sense based on what you know about the area?
• How does amount of precipitation affect the water balance? (site storm model)
• Which seasons contribute the most sediment to the stream? Why? (multi-year model)

Option B - Stormwater Management - Best Management Practices (BMP)

• What are the water-related issues on your campus or in your area?

• Identify potential issues on your campus that relate to storm-water runoff. For example, are there areas where water pools in a storm or gullies or rills that develop because water is not infiltrated? Take photos of them and annotate them to describe what is happening.
• Using what students have learned from the Generic Model, describe what combinations of storm intensities, land cover types and soil textures are most common on your campus.
• How do local conditions (impervious surfaces, fine soils, etc.) influence the fate of the rainwater in your area? Are there places on the campus where you often see puddles, erosion, deposition, or other results of storm runoff?

• Activity - Research different types of BMPs.

Each individual or group should select one of the BMPs below or develop one of their own, with the approval of the instructor. Each group should describe how the BMP is designed, built and maintained to address your local conditions. They should also discuss how, if at all, this BMP is modified to reflect the environment in which it is built (urban, rural, temperate, arid). In addition, they should provide information on the cost/sq. ft. of the BMP; the average reduction of runoff that it provides; where this BMP is best implemented (large scale development, single home, campus, etc.) and, finally, recommend where, if at all, this BMP should be integrated on or near their campus. Below is a list of typical BMPs. Also see references below.

• Green/vegetated roofs
• Permeable pavement
• Bio-retention cells
• Vegetated infiltration basins
• Rain gardens
• Grassed swales
• Rain barrels and cisterns
• Riparian buffers

Unit 7.1 - Day 2 (75 min total)

• Class Discussion (10 min) - Questions about model or results

Option A - Model My Watershed

Activity - Use "Model My Watershed" to investigate the impact of conservation practices on your watershed

• Launch the Model My Watershed App (either login as a User or a Guest)
• Zoom into some area of interest;
• For rural watershed-scale areas, turn on HUC-12 Watershed boundaries using "Select by Boundaries".
• For smaller urban areas, use "Draw Area" to define your area of interest. (Best choice for scenario analysis)
• Enter the Model Tab and select the "Site Storm Model"
• Start a new scenario by using the "+ Conservation Practice" tab in the upper left.
• Define one or more areas having a "new" conservation practice and compare how the area's water budget changes using the "Compare" icon in the upper right. Return to the previous page using the "Navigate Scenarios" link at the bottom left of the page.
• A turning ring icon is displayed under the "Runoff and Water Quality" icons to indicate when the model is recalculating values.
• Investigate at least 2 scenarios under the Model/Runoff Tab and write a short summary of the conditions and related water balance.
• Investigate at least 2 scenarios under the Model/Water Quality tab and write a short summary of the conditions and related water quality.

Option B - Stormwater Management

Activity - Student Investigations of Stormwater Management BMP's

• How can you modify your campus in a way that is acceptable to the community and improves the hydrology?

Using a Google Earth image of your campus, each group should indicate areas where you would recommend BMPs to reduce runoff. What BMPs would you recommend at each site? Why that BMP? You will find that BMPs are basically the same throughout different environments. However, they will use different vegetation that reflects local climate. These projects should be presented to the class. Presentations: Each presenter/group should develop a map with recommended changes to the existing conditions and a summary to provide an overview for classmates of what they recommend, what challenges they anticipate and how they addressed them.

• Individual or Group Presentations (3-4 min each, ~ 45 min): Each presenter/group should develop a map with recommended changes to the existing conditions and a summary to provide an overview for classmates of what they recommend, what challenges they anticipate and how they addressed them.
• Class Discussion (20 min): Once all students have provided their classmates with their scenario overviews, the class should discuss similarities and differences in treatments and what challenges they had improving the hydrology while reducing impacts on their community. They should also discuss whether there are any areas near where they live that have similar problems and how they might address those problems.

Pre/Post test

This unit has a Pre/post test to help you assess the students incoming and exit misconceptions and understandings. Try to set this up as a quiz on a course management system to allow the students to complete prior to the first class. The pre-test has a question on the definition of a watershed. If the results of that test indicate that students do not know the definition, then it will be important to include a greater emphasis on watersheds in this course. This unit does assume a certain level of geoscience knowledge, so be sure to look over the student handouts before assigning them to make sure your students are adequately prepared.

• Pre/post testing- this will not be graded, but will provide a way to measure the effectiveness of the unit, if desired. Students should complete the tests online before and after class, if possible.
• Assessment: Pre/post test w/ key (Microsoft Word 2007 (.docx) 833kB Feb12 17)

• Each group will complete a worksheet that documents the changes they made to arrive at the improvement(s). As homework, student pairs or groups will be asked to compare and contrast two best-management practices (BMP) to reduce runoff. They will compare the underlying design and engineering, as well as the efficacy (runoff and nutrient) and cost of the BMPs where each technique would be best applied. The reports will be handed in and graded.

• Model My Watershed Worksheet: Student Worksheet (Microsoft Word 2007 (.docx) 18kB Feb19 17)

• Each group will report to the class on their findings, which will be the basis for a class discussion. The worksheet and related screen capture images will be consolidated to provide their classmates with a 1-2 page overview of what they did, what challenges they faced and how they addressed them. That report should also address what trade-offs they made to achieve their environmental goals while preserving or improving social and economic conditions for the residents.

• Model My Watershed Presentation: Minor Class Presentation Rubric (Microsoft Word 2007 (.docx) 18kB Dec26 16)

• Students will also receive in-class participation scores for in-class discussions guided by the overall class discussion rubric:
• Class Discussion Rubric Class Discussion Rubic (Microsoft Word 2007 (.docx) 20kB Dec26 16)

• Total Points: Instructor's choice

Model My Watershed Instruction Sheets are available from WikiWatershed, an initiative of Stroud™ Water Research Center

• Finding Your Watershed
• Using Model my Watershed
• Using the Micro Site Storm Model

Best Management Practices

• EPA - National Menu of BMP's for Stormwater link
• USDA/NRCS - Unlock the Secrets of Soil - Soil Health
• USFS - National Best Management Practices (BMP) - Watershed scale
• UIext - Stormwater BMP - Start at home
• VA WRRC - Stormwater BMP Clearinghouse

Other Related resources

• TR-55 Model
• Using Curve Numbers (link unavailable)
• Related SERC activity: Watershed Delineation Unit
• Kid's Activity: Watershed World Activity (Acrobat (PDF) 189kB Aug2 13)
• This is a good resource for watershed water-quality: RiverWeb