Using 2D models to teach how and why watersheds flood

Wednesday 1:30-2:30pm PT / 2:30-3:30pm MT / 3:30-4:30pm CT / 4:30-5:30pm ET Online
Share-a-Thon Part of Share-a-Thon


Alan Berkowitz, Cary Institute
Bess Caplan, Cary Institute of Ecosystem Studies


At the Rendezvous, we will demonstrate how to use the Floorlandia model. Participants can practice using the model to 1) delineate watersheds, 2) demonstrate runoff, 3) simulate a flood event, 4) collect runoff data and create hydrographs.


We will demonstrate how to use a 2D watershed model to simulate how and why watersheds flood. The model, "Floorlandia," simulates water movement across an imaginary landscape, with students moving beads across a flat surface following elevation values. The activity shows how a computational model can be used to quantify surface water runoff and help students understand what must be programmed into a computer to model and run a simulation model of water flow. Outcomes for this activity include student ability to: 1) demonstrate how water flows from high gravimetric potential to low gravimetric potential; 2) explain how computational models can be used to represent real-world phenomena; 3) understand computational principles including discretization, time-stepping, parameterization, rules or algorithms and boundary conditions; 4) delineate watersheds; 5) collect first hand flood data and construct a hydrograph.


This activity is part of a larger module on the frequency and intensity of flooding in Baltimore-area watersheds. The activity occurs after students have defined the causes of flooding (precipitation and runoff), learned about local historical flooding events, and created a rainfall contour map using a physical model to simulate a rainfall event. The target audience is high school environmental science or computer science students.

Why It Works

The activity provides a very simple way for students to visualize watershed boundaries using elevation values on a 2D surface. Students are able to use dry-erase markers and static elevation values to delineate a watershed directly on the model. In addition, students use beads to simulate runoff from a storm event. The activity follows common computational concepts and practices such as iteration or time-stepping to slow down the process of runoff and allow students to capture quantitative data (i.e. the # of beads during each time step that exit the watershed) from the model. The activity can be used multiple times in a single class period with easy clean-up and easy transfer from one class period to the next.

Presentation Media

Slide show for Floorlandia Assignment (Acrobat (PDF) 859kB Jul14 20)
Comp Hydro Baltimore Lesson (Acrobat (PDF) 1.4MB Jul14 20)

Connection Information

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