Optimum Number of Raingauge Stations

Q. There are four raingauge stations existing in the catchment of a river. The average annual rainfall values at these stations are 780, 640, 400, 520 mm. Allowable percentage error in mean value of rainfall is 10%. The optimum number of rain gauges in the catchment should be ________.

1. 8

Q. A catchment has six rainguage stations. In a year, the annual rainfall record by the gauges are as follows

Station	A	B	C	D	E	F
Rainfall (cm)	76	85	101	130	88	110

For the 12% error in the estimation of mean rainfall, the optimum number of stations required in the catchment are

1. 1
2. 2
3. 3
4. 4

Q. There are four rain gauge stations existing in the catchment of a river. The average annual rainfall values at these stations are 800, 620, 400 and 540 mm. How many more gauges are required to be installed, if it is desired to limit the error in the mean value of rainfall in the catchment to 10%?

1. 5
2. 6
3. 4
4. 3

Q. The coefficient of variation of the rainfall for six rain gauge stations in a catchment was found to be 29.54%. The optimum number of stations in the catchment for an admissible 10% error in the estimation of the mean rainfall will be

1. 9

Q. The coefficient of variation of the rainfall for six rain gauge stations in catchments was found to be 29.54%. The optimum number of stations in the catchments for an admissible 10% error in the estimation of the mean rainfall will be

1. 3
2. 6
3. 9
4. 12

Q. The percentage standard error of precipitation averages is often expressed functionally or graphically in terms of (i) precipitating gauge network density expressed as area per gauge, and (ii) total area of catchment. The percentage standard error

1. increases with area per gauge as well as with total area
2. decreases with area per gauge as well as with total area
3. increases with area per gauge but decreases with total area
4. decreases with area per gauge but increases with total area