(I. Hydrology (10%) MODERATE, DIFFICULT

Question 1

18. The precipitation depth that corresponds to a liquid quantity of 1 liter falling into a 1 square meter of ground area.

A. 0.5 mm
B. 1 mm
C. 2 mm
D. 2.5 mm

Answer 1

Answer: B

Solution:
Precipitation = (1 liter x 1,000,000 mm3/liter) / (1 m2x 1,000,000 mm2/m2) = 1 mm

Question 2

19. Probability of occurrence in any year of hydrologic event recurring once in 4 years.

A. 40%
B. 25%
C. 20%
D. 50%

Answer 2

Answer: B

Solution:
Probability = (1/Return Period) x 100% = (1/4) x 100% = 25%

Question 3

20. What is the probability of occurrence in any year of a hydrologic event recurring every year?

A. 100%
B. 10%
C. 20%
D. 50%

Answer 3

Answer: A

Solution:
Probability = (1/Return Period) x 100 = (1/1) x 100% = 100%

Question 4

21. Rainfall depths recorded were as follows: 8mm and 2mm for 8:00 A.M. and 2:00 P.M., respectively on 7-7-2022 and 5 mm and 9 mm for 8:00 A.M. and 2:00 P.M., respectively on 7-8-2022. What is the total rainfall depth on 7-7-2022?

A. 0.5 mm
B. 1 mm
C. 2 mm
D. 2.5 mm

Answer 4

Answer: C

Solution:
The rainfall recorded at 8:00 AM of any day is counted as part of the total rainfall for the
previous day.

Rainfall on 7-7-2022 = Rainfall at 2:00 P.M. on 7-7-2022 + Rainfall at 8:00 A.M. on 7-8-2022
= 2 mm + 5 mm
= 7 mm

Question 5

22. The agrometeorological station uses electronic rain gage. The rainfall depths were recorded on
    June 1, 2022 as follows: 2 mm from 6:00 to 8:00 A.M., 7 mm from 8:00 to 10:00 A.M., 9 mm from 12:00 noon to 2:00 P.M. and zero rainfall for all other times of the day and the previous day. What is the rainfall intensity recorded on June 1, 2022?

A. 0.75 mm/hr
B. 2 mm/hr
C. 4 mm/hr
D. 3 mm/hr

Answer 5

Answer: C

Solution:
Intensity = Depth/Time, time is from 8:00 AM of current day to 8:00 AM of the next day
= (7mm from 8:00 to 10:00 A.M. + 9mm from 12:00 noon to 2:00 P.M.)/(2hr +2 hr)
= 4 mm/hr

Question 6

23. Estimate the time of concentration of a certain watershed having a time lag of 1 hour.

A. 1.43 hours
B. 1.34 hours
C. 14.3 hours
D. 13.4 hours

Answer 6

Answer: A
Solution:
 Using the formula for time of concentration from PAES 609:2016,
 TC = TL / 0.70
= 1 hr / 0.70
= 1.43 hrs