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<br />~ <br />, <br /> <br />CONCEPT 3: Groundwater flows from upland areas to low areas, or from areas of <br />high pressure to areas of lower pressure (hydraulic head). <br /> <br />Action: Allow water to run through the model. Add dye to one or more <br />of the piezometers until the dye moves into the sand. NOTE: This works <br />best if you add dye before the water begins to fill the piezometer. <br /> <br />Discussion: The dye that moves into the sand is carried along by the <br />moving water so you can see the path and direction of flow. Primary <br />movement of the dye will be in a downgradient direction. <br /> <br />CONCEPT 4: The texture of the materials in an aauifer affects the rate of <br />flow throuQh the aauifer. <br /> <br />Supplemental Activity: Groundwater Movement (Extension 2) <br /> <br />Action: Inject dye into the 3 injection wells (see diagram for <br />location). Notice that the dye injected into the coarse sand wedge <br />(middle injection well) disper~es much faster than the dye injected into <br />the fine sand. Dye in the gravel disperses the fastest. <br /> <br />Discussion: Water flowing through an aquifer will take the path of <br />least resistance. Water will move through well-sorted gravel faster <br />than well-sorted sand because larger grain size leads to larger pore <br />size which leads to less surface area in the water contacts, and less <br />frictional resistance for the moving water. Lower frictional resistance <br />leads to greater velocity of groundwater flow. <br /> <br />CONCEPT 5: Water flows into rivers and lakes from many directions. <br /> <br />Action: Open the clamp on the plastic tube by the lake. Put a second <br />one liter bottle on the other end of the model (the discharge area <br />becomes a recharge area). Add two different diluted dyes to the <br />piezometers nearest the lake. Watch the colors reach the river (or lake <br />if you close the clamp). <br /> <br />Discussion: Rivers are natural discharge areas for groundwater. In the <br />model, you will see the dyes move from all directions towards the <br />river/lake. <br /> <br />CONCEPT 6: Groundwater is related to surface water and to all other forms of <br />water found on earth through the water cvcfe (hydrologic cycle). <br /> <br />Action: Keep the plastic tube closed and allow water to begin to fill <br />in the lake. This shows how groundwater becomes surface water. <br /> <br />Action: Remove the bottle from the outlet and release the clamp on the <br />plastic tube at the outlet. Allow the surface water of the lake to soak <br />into the ground (use of a color dye helps students see this movement <br />into the ground). This shows how surface water becomes groundwater. <br /> <br />2 <br />