The area between the isohyets 45 cm and 55 cm is 100 square km and between 55 cm and 65cm is 150 square km. The average depth of annua! precipitation over the above basin of 250 square km will be
A)50 cm
B)55 cm
C)56 cm
D)60 cm

Question

Quizplus · Accepted Answer

The average depth of annual precipitation over the basin can be calculated by taking the weighted average of the precipitation depths over the respective areas. For the area between 45 cm and 55 cm (100 square km), the midpoint precipitation depth is 50 cm. For the area between 55 cm and 65 cm (150 square km), the midpoint is 60 cm. The total precipitation volume is (50 cm * 100 km²) + (60 cm * 150 km²) = 5000 cm-km² + 9000 cm-km² = 14000 cm-km². The average depth over the entire 250 square km area is 14000 cm-km² / 250 km² = 56 cm.

The Area Between the Isohyets 45 Cm and 55 Cm