Names:
It’ll Go With The Flow…
Background: Groundwater usually flowsin the same direction as the land slopes,often toward a nearby lake or stream. Many factors, such as rate of percolationfrom the surface and pumping fromwells, can influence the direction and rateof groundwater flow, but it is possibleto get an idea of how groundwater ismoving in a given area by determiningthe slope or “plane” of thewater table.To do this, at least three monitoring wellsmust be installed (three points determinea plane). By measuring the “static waterlevel” (SWL), or elevation of the watertable above sea level, we can estimatehow groundwater will flow at a certainlocation. Water table contours lines are constructed to join areas of equal static water levels.
Groundwater flows from areas of highstatic water levels to areas of low staticwater levels. This can be illustrated using abook and a marble. The marble will roll offthe book in the direction of the slope andthe speed of the marble will be determinedby the steepness of the slope. Groundwatermoves in much the same way. The rate of groundwater flow can be determined by looking at the distance between the contour lines. Contour lines that are close together would indicate a steeper plane than those that are farther apart. The steeper the plane the faster the rate of groundwater flow.
It is important to consider the directionand rate of groundwater flow when planningland development to avoid potentialcontamination problems. Using staticwater level data, you will be asked todetermine the general direction and relative rate of groundwater flow on a givenmap, and evaluate a proposed landfill siteon the basis of this information.
Questions to Answer (put answers on another sheet of paper):
- What do the contour lines on your map show?
- What is "static water level?" How is it different from water table depth?
- How does the plane of the water table affect groundwater flow (direction and rate)? What other factors might influence groundwater flow?
- In what general direction does groundwater flow in PleasantValley (use the compass)?
- Can we make assumptions about the speed of groundwater movement at certain locations? Explain.
- What is the level of Mud River as it passes by town?
- Is the star a good location for the landfill? Why?
- Propose an alternative location for the landfill. Mark this location with an “X” on the map. Explain why you think your alternative site would be a better location.
**The groundwater flow at any point on your map is perpendicular to the contour lines at that location.