Question

Problem 1 (10 po There are 7 rain gauges in and near the watershed shown in the figure below. During a storm event, rainfall depths were recorded at 5.13 inches for Gage A, 6.74 inches for Gage B, 9.00 inches for Gage C, 6.01 inches for Gage D, 5.56 inches for Gage E, 4.98 inches for Gage F, and 4.55 inches for Gage G (1). Draw the Thiessen polygons in the figure below (2) Estimate the average rainfall depth over the watershed using the Thiessen polygon method

Treat each square box as 1 inch

Answer 1

Procedure to draw thiesson digram

1) Indentify rainguage stations within catchment

2) Join all adjucent stations by straight black lines

3)Draw perpendicular bisectors by red colour lines, the area enclosed by bisectors and boundary of catchment represents poligonal area

4) measure the area of each polygon by measuring total number of square boxes come in poligonal area in square feet

5) Calculate total catchment area by measuring total square boxes in catchment.

THIESSEN DIGRAM IS

2) mean precipitation is calculated as