Annual rainfall at a point M is needed. At five points surrounding the point M the values of recorded rainfall together with the coordinates of these stations with respect to a set of axes at point M are given below. Estimate the annual rainfall at point M by using the USNWS method. Station A B C D E 10.8/ Rainfall P (cm) 10.2 A 11.2 D 102 120 126 108 131 13.2 'c 9.2 11.7 E 14.0 10.9 H 0 Coordinates of station (in units) ENGG Fig. 2.25 Problem 2.9 2.0 2.0 3.0 1.5 4.5 SCALE 6.3 5 km 3.6 8.2 F Y 1.0 2.0 1.0 1.0 1.5 Hint: In the US National Weather Service (USNWS) method the weightage to the stations are inversely proportional to the square of the distance of the station from the station M. If the co-ordinate of any station is (x, y) then D2+ and weightage EPW W=1/D. Then rainfall at M = P =