Groundwater First Test Fall 2010
Closed book portion: one page one side cheat sheet
Open book portion: cheat sheet and book, no notes
Take home: laboratory exercises a) horizontal flow, b) confined aquifer, c) unconfined aquifer (image wells); pump test example (from internet site)
1. (3) (T/F) An element is defined by the number of neutrons in the nucleus.
2. (3) (T/F) Stable isotopes are radioactive.
3.. (T/F) In the capillary fringe:
a) (2) the surface tension is greater than at the water table
b) (2) the water pressure is higher than at the water table
c) (2) the height of the capillary fringe is lower in clay than in sand
4. (3) (T/F) When flow crosses a boundary with a change in hydraulic conductivity the flow usually changes direction
5. (3) When the barometric pressure rises, the water levels in confined aquifers ______
6. (6) Which of the materials in the triangle of soil textures has the largest specific surface?
Which has the highest hydraulic conductivity?
Which has the lowest hydraulic conductivity?
7.(6) Draw the water table between A and B if W (recharge) = 0.
8.(4) A suction pump can raise water about 25 feet on a practical basis (the theoretical limit is about 34 feet). Is the 25 feet the distance between the pump and point b (the water table) or point a (the water intake point)?
9. (3) Which one has the highest uniformity coefficient? Loess, dune sand, or alluvium
10. (12) Draw flow lines, show areas of recharge and discharge of groundwater.
11. (3) The quality of a water chemistry dataset can be checked by:
a) Stiff diagram
b) cation/anion balance
c) Piper plot
d) Anapera Error Analysis diagram
12. (4) Rank the points a and b in order from highest to lowest hydraulic head.
13. (4) The slide below shows the single well model with no pumping. Show what the dye plumes look like at steady state when the well is pumping.
14. (3) What is the specific capacity of a well?
15. (4) The well on the right is pumped. Where would you place an image well to compensate for the impermeable boundary on the right when estimating the drawdown? Would you pump into or out of the image well?
16. (3) Methods of well development include pumping, surging with air or water, adding chemicals, and hydro fracturing. What I don’t understand is why we develop wells. We do it to increase ______, prevent sanding, improve water quality, and increase economic life of the well.
1. (10)
Given the equation for transient, three dimensional, heterogeneous, anisotropic media; find the equation for:
a) steady state, homogeneous, isotropic media
b) transient, homogeneous, anisotropic media
must show your work!
2.(10) The confined aquifer has a simple one dimensional gradient in piezometric head as shown with a slope of 20 feet/mile. (a mile is 5280 ft). If the aquifer has a hydraulic conductivity of 10-4 cm/s, a thickness of 30 m, a porosity of 0.23. Find: specific discharge, pore velocity, transmissivity.
3. (10) Work problem 4.1.2, page 198. Assume porosity of confining layer is 0.25.
4. (10) Estimate the amount of net soil moisture use by plants in July and August in inches. Show your work.