WHERE DOES RAIN GO? A MULTIPHASE LAB EXERCISE ON WATER AND SOIL EROSION

A commonly held misconception about water is that it flows in underground rivers (USGS, https://pubs.usgs.gov/gip/gw/how_a.html). One possible explanation for this is that it is difficult to visualize what is below ground. The learning objective of one of the lab sessions in Geology/Astronomy 106L, a two-hour, one-credit lab required for elementary education majors, is the understanding of surface and groundwater flow, and how it affects the landscape and water usage.

To help students visualize the processes that involve water flow, we have created a series of short, 20-30 minutes activities that address key water concepts. The first concept is the effect of rainfall on soil erosion. We asked an outreach group related to ISU Extension, Water Rocks!, to create a video of the rainfall simulator that they use to give demonstrations to school children, farmers, and students. The 20-minute video (https://www.youtube.com/watch?v=8xlrBcHf3HM&feature=youtu.be) shows five different undisturbed samples of soil with intense, minimum or no tillage, a green roof with hardy plants, and an urban environment with pavement. Students are asked to hypothesize what will happen when a sprinkler that simulates rainfall is turned on, and water flows through the trays and collects in beakers.

A second activity uses ‘antfarms’, or groundwater flow models, where students use food coloring to visualize the flow of potential contaminants in a groundwater reservoir tapped by various wells. To complement this, we created a physical model of a landscape in Wyoming using a 3D printer. The landscape includes a slope and a river valley. The goal of the activity is for students to place a drinking water well on the slope given the location of houses, a chemical plant, a landfill, and farm animals. This is accomplished using worksheets to guide students’ inquiry in surface and groundwater flow in a mountainous landscape.

Students also have chance to use our new Augmented Reality Sandbox to explore the relationship between topography and surface water flow, as well as using a stream table to investigate stream flow dynamics. Students greatly enjoy the interactive nature of these activities and engage well with some of the more inquiry-based activities, such as using the stream table to create their own experimental setup to investigate stream flow.