The spatially averaged rainfall is to be calculated for the catchment area shown

Question

The spatially averaged rainfall is to be calculated for the catchment area shown in the figure below. There are five rain gages in close proximity to the catchment area, and the Cartesian coordinates (x,y) and rainfall P, measured at these gages during a particular 1-hour interval are as follows:

Gage

y (km)

A

7.0

B

3.7

C

4.2

4.9

30

D

3.5

1.4

5

E

2.1

-1.0

25

Use the Thiessen grid method with the 1km by 1 km grid shown in the figure to estimate the average rainfall over the catchment area during the 1-hour interval. Use Table 9.3 in the textbook and change the values in Column 9. Use Excel for calculation.

Gage

x (km)

y (km)

P (mm)

A

1.3

7.0

70

B

1.0

3.7

10

C

4.2

4.9

30

D

3.5

1.4

5

E

2.1

-1.0

25

Column 6 Row 7 1 km Catchment 7 Column 1 Row 1 6 km

Explanation / Answer

Average Rainfall P bar is

P bar = P1A1+P2A2+P3A3+...............PnAn/A1+A2+A3.....An

= 1707.2/28.91

= 59.07 mm

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.