Exam: Section 3 - Field measurements

1. Draw the hydrologic cycle and explain its importance.

2. In doing a watershed inventory, what physical characteristics should be analyzed?

Answer:

3. List 3 methods used to measure water flow in a small stream, and describe their installation.

Answer:

bucket/stopwatch method
float/area method
weir method

4. What is the flow rate in cubic feet per second (cfs) of a 6 L/sec flow rate?

Answer: 6 liters per sec. x.0353 cfs/liter per second =.21 cfs

5. On a slope of 1.5%, what is the elevational rise in a horizontal distance of 150 m?

Answer: 1.5/100 = x/150 x = 2.25 m

6. Why is slope such an important concept in irrigation practices and agriculture in general?

7. Using the hand-feel method, determine the texture of the soil sample supplied.

8. How much water might you expect a sandy loam soil to hold between field capacity and wilting point in a one-meter depth?

Answer: = 100-130 mm/m

9. Define: (1) saturation, (2) field capacity, and (3) wilting point.

Answers: Saturation - occurs when all the pore space in a soil is filled with water.

Field capacity - the moisture status of the soil after drainage due to gravity ceases, and the soil retains its maximum amount of water against the force of gravity. This generally occurs 1 to 4 days after saturation.

Wilting point - the point at which water becomes unavailable to the plant; the soil holds on to water tightly.

10. How deep would you normally expect corn roots to go in a soil without hard layers or other obstacles to root penetration? How deep in a soil with a hardpan (hard clay layer) at 30 cm?

Answer:

without obstacles, (1 meter
with hard pan, (30 cm