Abstract

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.

Context

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.