5 points During a storm gage station A was inoperative but t

[5 points] During a storm, gage station A was inoperative but the surrounding stations B, C, and D, recorded rainfall of 5.2, 4.5, and 6.1 inches, respectively. The average annual precipitation for stations A, B, C, and D are 48, 53, 59, and 67 inches, respectively Estimate the storm precipitation for station A. #4 [2+5+5 points] The rainfall was recorded at the network of stations over a trapezoidal watershed 20 mi 5 mi (see figure below). Determine and compare the average rainfall using: 5 mi a) Arithmetic average method b) Thiessen polygon method c) Isohyetal method 5 m 85 mi Station | Precipitation (in.) 45 mi 2.8 3.5 4.2 5.1 6.0 4.5 3.9 45 m 25 mi 5 mi D 5 m 5 mi

Solution

By normal ratio method

Pa=Na/4(Pb/Nb+Pc/Nc+Pd/Nd)

=48/4(5.2/53+4.5/59+6.1/67)

=3.1851inches