Problem 1
Imagine that you have a box that is 15 centimeters (6 inches) square. You also have a never-ending supply of rectangular sticks measuring \(15 \times 3 \times 3\) centimeters \((6 \times 1.2 \times 1.2\) inches). How could you arrange the sticks in the box to model a system with very low porosity \((\sim 0\) percent) and high porosity ( \(\sim 40\) percent)?
Problem 2
Imagine that you have three identical containers (A, B, C) filled with flour, uncooked rice, and coffee beans, respectively. Predict what would happen if you were to pour water into each container. How would they rank in terms of permeability (from highest to lowest)? Explain your thinking.
Problem 8
Student Answer Evaluation Exercise In response to the question "Is there groundwater below lakes?" a student wrote the following response. The instructor gave the answer a score of 7 out of 10 and wrote the following comment on the assignment: "You have clearly understood some of the concepts related to this topic, but you have not yet pulled all the key ideas together. Think a little more about the difference between surface water and groundwater systems." Review the student's answer, and write a more complete response. Is there groundwater below lakes? No, there should not be any groundwater below lakes. Groundwater is present in rocks with good porosity and permeability. If rocks under a lake had good porosity and permeability, then the water from the lake would drain out into the groundwater and the lake would be gone. But if the rock under the lake had bad permeability and porosity. then water could not move into it and the lake would not lose water.
Problem 9
Two wells (A and B) are drilled in rocks that have the same porosity, but the rocks around well A have a higher permeability than those around well B. Suppose both wells are pumped at the same rate. Which statement is true? a) Well A will have a larger cone of depression. b) Well B will have a larger cone of depression. c) The cone of depression will be the same for both wells.
Problem 13
Which is the best explanation for the changes in water level in the High Plains aquifer? Explain why you chose your answer. a) The distribution of present-day rainfall on land above the aquifer b) Differences in the thickness of the rocks that make up the aquifer c) The number of water wells that have been drilled into the aquifer d) The type of crops supplied by irrigation from the aquifer
Problem 14
Sketch and label a graph illustrating changes in water levels in part of the High Plains aquifer from 1900 to 2000 . Assume that wells were not drilled into this part of the aquifer until 1940 and that the area is currently experiencing groundwater overdraft.
Problem 16
Much of the agriculture in the middle United States relies on water from the High Plains aquifer. What are the longterm implications if we continue to use large volumes of groundwater for irrigation faster than it can be replenished?
Problem 24
Wetland Management Exercise After graduation, you begin work for your local county government. A few years later, you are put in charge of the local park system. One park includes a wetland area in the meander bend of a river. A boardwalk has been built out into the wetland so that residents can admire the water lilies, watch for fish, and sit at dusk to look for beaver and ducks. Part of your job is to monitor the health of the wetland. There is some concern that it is starting to be overrun by a type of water grass that will push out other vegetation and change the character of the area. What kinds of factors could you survey annually to measure the general health of the wetland? How could you monitor the status of the water grass?
