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**Essay Questions**

Click here to access the Equation Sheet.

22. (head-darcy) An artesian aquifer is overlain by three soil layers and a small pond as shown below. How much water flows into the pond (in ft^3) from the aquifer per square foot of area in **one month's** (30 days) time?

23. (modflow) What is a **drain**? How are drains simulated in MODFLOW?

24. (head-darcy) For a soil deposit with **horizontal** layering of heterogeneous deposits, which is

greater, Keq for the horizontal direction or Keq for the vertical direction? Why?

25. (modflow) Enter a short description for each of the following terms associated with the **Evapotranspiration** package:

a. Max ET Rate

b. ET Surface

c. Extinction Depth

26. (gw-concepts) Describe the three basic **types** of ground water models.

27. (head-darcy) The water level in an observation well A is measured at **3785.4** ft. At a point **1238** ft downgradient from that point, the water level in a second well (B) is measured at **3629.3** ft.

a. What is the hydraulic gradient between the well A and well B?

b. Assuming that the hydraulic conductivity is 3.0 ft/day and the effective porosity is 0.3, what is the seepage velocity between the two points? [ft/day]

c. How long would it take for a particle to travel from point A to point B? [days]

Show your work and label your answers.

28. (modflow) Suppose you wish to represent the soil profile shown below in a MODFLOW model using a single layer. What values would you enter for the equivalent **horizontal** and **vertical** hydraulic conductivity? Put your answers in [m/d].

29. (head-darcy) For the previous problem, assume you got **0.01** m/d for Kv. Also assume that the effective porosity is **0.2** and that the head at the top of the profile is **1024** m and the head at the bottom of the profile is **1020.5** m. How long would it take [in days] for water to travel from the top of the profile to the bottom?