1. A rectangular, sharp-crested weir with end contraction is 1.5 m long. How high should it be placed in a channel to maintain an upstream depth of 2.5 m for 0.5 m3/s flow rate?
2. The following information was obtained from a discharge measurement on a stream. Determine the discharge.
Distance from bank (ft)
|
Depth (ft)
|
Mean velocity (ft)
|
0
|
0.0
|
0.00
|
12
|
0.1
|
0.37
|
32
|
4.4
|
0.87
|
52
|
4.6
|
1.09
|
72
|
5.7
|
1.34
|
92
|
4.3
|
0.71
|
100
|
0.0
|
0.00
|
3. An experiment was conducted to determine the hydraulic conductivity of an artesian aquifer. The piezometric heads at two points 150 m apart were found to be 55 m and 48.5 m above a datum. A tracer injected into the first piezometer was observed after 32 hours in the second well. A test on porosity of a sample of the aquifer shows that α = 24%. What is the hydraulic conductivity of the aquifer? Suggest what the aquifer material may be and verify that your solution holds true. Take the subsurface temperature as 15°C.
4. Suppose an unconfined aquifer lies over a confined aquifer as shown in Figure. Deternine the flow out of both aquifers.
5. Three monitoring wells are used to determine the direction of groundwater flow in a confined aquifer. The piezometric heads in the wells are found to be 52 m in well 1, 49 m in well 2, and 56 m in well 3. Determine the direction of flow.
6. A 50-cm diameter well fully penetrates vertically through a confined aquifer 12 m thick. When the well is pumped at 0.035 m3/s, the heads in the pumped well and the two other observation wells were found to be as shown in Figure. Does this test suggest that the aquifer material is fairly homogeneous in the directions of the observation wells?
7. The following data were obtained in an observation well 80 m away from the pumped well. The discharge from the pumped well was at 2.5 m3/min. Using Jacob's approximation, determine the aquifer properties. Assume a confined aquifer. Also verify your solution and determine the time after which Jacob's approximation will be valid.
Time (min)
|
Drawdown (m) |
0.5
|
0.16
|
1
|
0.18
|
2
|
0.24
|
3
|
0.27
|
4
|
0.47
|
5
|
0.50
|
7
|
0.57
|
10
|
0.68
|
20
|
0.84
|
30
|
0.96
|
50
|
1.06
|
100
|
1.29
|
200
|
1.46
|
500
|
1.68
|
1000
|
1.86
|