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Groundwater Principles: A Hands-On 3-D Classroom Activity To Determine Groundwater Flow Direction & Gradient
A groundwater hydrology course provides insight into fundamental theories and properties of groundwater flow through aquifers. Determining direction of groundwater flow as well as gradient is an important aspect within the course. A widely used technique to determine flow direction and gradient is known as the “three-point problem”. Solving a three-point problem requires knowing the groundwater elevation of three points that are not in a straight line, and the distances between the three points. The three-point problem utilizes simple geometry principles to determine both the direction of flow and gradient. In geometry, three points define a plane; knowing the groundwater elevations defines the plane in hydrogeologic space, allowing the inclination/gradient to be determined. Basic groundwater principles state that groundwater flows down-slope in aquifers, allowing direction of flow in a homogeneous, isotropic aquifer to be determined using this method.
This paper shows how utilizing a 3-dimensional hands-on activity can be more engaging than a traditional lecture. To better visualize the three-point problem, a hydrogeologic system is simulated in a classroom setting using low-cost materials which can be commonly found at hardware stores. Required materials consist primarily of PVC pipes and fittings, string/yarn, and a measuring device. The low-cost and simple technology requirements of the activity can be easily re-created at other educational institutions. The activity allows students the opportunity to apply what they’ve learned and visually see what is occurring in a 3-dimensional space, as opposed to simply solving the problem graphically in 2-dimensions on paper. Pipes are placed from floor to ceiling in a classroom, and string is used to mark the groundwater depth on each pipe. The ceiling acts as ground surface and everything in the room is considered to be below-ground. String is also used to mark the isocline line as well as the sloped groundwater flow line.