15. Rank the following stream discharge data. Given that RI =...

15. Rank the following stream discharge data. Given that RI = (N+1)/Rank and the values below, 

determine the recurrence interval for each data point. Show your work (1 pt).

Discharge

(cfs) Rank RI

1010

900

400

590

Plot and draw a best-fit line through the data, and determine the discharge of a 100-year flood 

(2 pts).

16. A drainage basin bordering the sea has an area of 8000 km2. The average precipitation for this 

drainage basin is 700 mm per year. What volume of precipitation falls on the basin each year (1 

pt)?

17. A piezometer is screened 800 meters above sea level (in a water aquifer). Water level in the 

piezometer is at 805 masl.

e.  What is the hydraulic head at the screen (1 pt)?

f. What is the elevation head at the screen (1 pt)?

g.  What is the pressure head at the screen (1 pt)?

h.  What is the pressure? (1 pt). Assume that the density of water = 1 gram / cm^3

 

18. Water flows through a sand body that has been placed between two screens in the apparatus 

shown. The water levels to the left and right are kept at constant levels. The screens keep the 

sand in place but allow water to pass.

z1 = 35 cm p1/(rho)(g) = 15 cm

z2 = 10 cm p2/(rho)(g) = 30 cm

L = 100 cm r = 2 cm

K = 10 cm/day ne = 0.3

a.  Draw an arrow through the sketch indicating which direction the water flows (1 pt).

b.  Determine the hydraulic gradient (1 pt).

c.  Determine the volume flux Q in the sand 

body (1 pt).

d.  Determine the travel time of a water particle that flows through the sand body (1 pt).

The following questions ask you to utilize flow nets. If you have not yet received feedback on your flow net homework, feel free to contact Dr. Courtland for feedback before / while completing this portion of the exam. Note that I will only answer questions related to the homework and will not explicitly provide advice for the exam.

19. Determine the flow (q) under the dam. Hydraulic conductivity of the foundation soil is 2.5 x 10-

5 m/s. The upstream water level is Datum (2 pt).