Question

In a watershed, four raingauges I, II, III and IV are installed. The depths of normal annual rainfall of these stations are 60, 75, 80 and 100 cm respectively. The rain gauge at station III went out of order during a particular year. The annual rainfall for that year, recorded at the remaining three stations was 90, 60 and 70 cm. The rainfall at station III can be considered as

• A. 60 cm
• B. 70 cm
• C. 80 cm
• D. 120 cm

Answer 1

The correct option is C 80 cm

Since the normal annual rainfall of stations I, II and IV does not lie within 10% of that of normal annual rainfall at station III. So,
Using Normal Ratio Method
$P_{III}=\frac{80}{3}[\frac{90}{60}+\frac{60}{75}+\frac{70}{100}]=80\text{cm}$