Write your name here: This exam counts 20% of your grade for this course; your instructions are as follows: 1) You have 75 minutes to finish this exam. 2) No books, notes, or discussion is allowed. If you have questions please ask the proctor. 3) It is your responsibility to communicate your understanding of the subject matter. 4) State any, and all, assumptions that you make in answering these questions. 5) Please remember the importance that your instructor attaches to units and significant figures. Section 1: (3 points each, 30 points total) Multiple guess; answer 10 and only 10 of the questions in this section by clearly circling the single best answer. Clearly mark the question that you don t want graded. No partial credit will be given. 1) Plants that tap the groundwater table and transpire large amounts of water are known as: a) phreatophytes c) xerophytes b) hydrophytes d) toxophytes 2) The following equation (inflow - outflow = change in storage) is known as: a) Darcy s Law c) Manning Equation b) Hydrologic Equation d) Horton Equation 3) Stream flow is often measured with a device that dams the river and forces flow to pass through a notch. This device is called a: a) gaging station c) pygmy meter b) Manning dam d) weir 4) This type of rock typically has low primary porosity due to an interlocking crystalline structure: a) sedimentary c) volcanic b) metamorphic d) pyroclastic 5) The measure used to express the volumetric fraction of water that drains from a given volume of aquifer under the force of gravity is the: a) specific storage c) specific yield b) porosity d) saturation
6) Given the total volume, water volume, and specific yield of any field soil sample you can calculate: a) saturation c) porosity b) specific retention d) none of these 7) Evapotranspiration is commonly measured in a: a) lysimeter c) hygrometer b) phreometer d) transometer 8) Most of the fresh water on earth is contained in: a) oceans c) ground water b) rivers, streams, and lakes d) ice caps and glaciers 9) The number of grams of water contained in a cubic meter of air is the: a) relative humidity c) dew point b) saturation humidity d) absolute humidity 10) This quantity can have a value that is greater than one (100%): a) porosity c) specific yield b) saturation d) none of these 11) If evapotranspiration within a given watershed is reduced (i.e., crop change) surface runoff will probably: a) increase b) decrease c) stay the same
Section 2: (5 points each, 10 points total) Answer two and only two of the following questions regarding Cadillac Desert by Mark Reisner 1) Reisner is critical of the reclamation act, and in particular the concept of 160 acre homesteads; what did he (and John Wesley Powell) think was wrong with this concept? 2) Reisner describes the role railroads played in settling the Western United States. What is the primary reason that he gives for the railroad companies enthusiastic efforts to induce new settlers?
3) Reisner reports on several methods that were used to fraudulently attain land grants during settling of the Western United States; describe one such method. Section 3: (5 points each, 30 points total) Answer six and only six of the following questions. Clearly mark the question that you do not want graded. Show your work CLEARLY for partial credit 1) Land pans are commonly used to estimate evaporation from lakes; describe this device and explain why evaporation from the land pan will be different than from the lake itself. 2) Using examples, explain the difference between primary and secondary porosity.
3) Draw and label diagrams that show how the water table relates to: 1) a gaining stream; and 2) a losing stream. Be sure to clearly indicate direction(s) of groundwater flow. 4) Given a dry soil sample that has a total volume of 1.1 liters and 40.0% porosity, calculate the volume of water in cm 3 that is required to bring the sample to 70.0% saturation. 5) Explain the difference between the terms porosity and effective porosity
6) Describe the porosity found in volcanic rocks such as lava flows. 7) Explain how a stream might change from gaining to losing Section 4: (10 points each, 20 points total) 1) A sample of soil with a known porosity (n) of 37% loses 110.0 cm 3 of water during oven drying. Assuming an initial saturation of 65% calculate the total sample volume (V t ) in cm 3. V t =
2) The small basin drawn below has 5 rain gauges; draw Theissen polygons for this basin. Explain why this method of calculating an average rainfall is superior to simply taking the arithmetic average of the five gauges. 5 + + 2 + 4 + 3 1 +
Section 5: (10 points total) These questions all refer to the permeameter shown below. Flow is assumed to be steady, the media is homogeneous and isotropic (K = 37.0 cm/hour and porosity = 0.35), the permeating fluid is pure water at standard temperature (density = 1 gm/cm 3 ) and crosssectional area of the permeameter is 27 cm 2. Show your work CLEARLY for partial credit. 1) Calculate volumetric flow rate (Q) through the system. 2) Calculate total, pressure, and elevation heads at points A and B. location total head elevation head pressure head Point A Point B