The total capacity of a reservoir is 25 million cubic metres and dead storage is 5 million cubic metres. If the average volume of sediment deposition is 0.10 million cubic metre per year, then the usefulness of the reservoir will start reducing after
A. 50 years
B. 150 years
C. 200 years
D. 250 years
Answer: Option A

50 year
ist calculate live storage = total capacity - dead storage = 25 - 5 = 20million metercubic
then number of year = live storage capacity / sediment deposition in each year = 20 / 0.1 = 200 year
therefore the correct answer is 200 year
After filled up the dead storage the usefulness of the reservoir will start reducing
The storage will be filled up in
5/0.10 = 50 years
How