Abstract
Buildings on many campuses have basements that project down into the water table. These buildings deflect groundwater flow and fundamentally change the flow pattern. In the case of our campus, groundwater that used to travel as a broad sheet toward the Mississippi River gorge in the Twin Cities now must follow a tortuous path between many structures. To prevent basement flooding, each building has a large sump that collects groundwater flow that moves along the outside of the building's substructure. So water that once flowed naturally to springs, seeps and creeks is now pumped into storm sewers that direct this flow to the Mississippi River. These sumps provide an excellent opportunity to enlighten our community about our campus' impact on groundwater and to create a valuable teaching tool for geology, biology and environmental science courses. Using open-source, Arduino micro-controller board technology (Enviro-DIY Mayfly boards) and relatively low-cost ultrasonic sensors, we built and deployed three sensor/datalogger stations on campus to monitor groundwater flow that passes through these sumps. The data are telemetered, over a wifi modem attached to the microprocessor board, to the Monitor My Watershed website, where anyone can look at the status of water flow in real time. They can also download textfiles of the sensor data to investigate the timing of groundwater pulses through the campus and to examine changes in groundwater flow over long time spans. We have made the plans for these sensors available on Github and we hope to add other sensors over time, such as conductivity and temperature probes. Finally, we also would like to work with a local artist to use the data from these sumps to create a visually appealing art installation that dynamically shows how the hidden water on our campus moves beneath our feet.