57. The rainfall cycle period in India is taken as
A. 15 years
B. 20 years
C. 25 years
D.35 years.

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58.  Pick up the correct statement from the following : actual rainfall in a year at a place
A. Index of wetness ?normal rainfall of that place
B.(b ) Normal annual rainfall is obtained by taking the mean of the annual rainfall over a period of 35 years
C. Index of wetness gives an idea of the wetness of the year
D. All the above.

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59.  Isohytes are the imaginary lines joining the points of equal
A. pressure
B. height
C. humidity
D. rainfall.

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60. The area enclosed by the adjacent isohyets of a catchment basin are shown under : Isohyets in ctns I 40-50 I 50-60 160-70 70-80 I 80-90 Area in sq. km I 1500 , 2500 I 3000 2000 1000 The average depth of annual precipitation in the catchment basin will be
A. 60.0 cm
B. 60.5 cm
C. 61.5 cm
D. 63.5 cm.

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61.  For determination of average annual precipitation in a catchment basin, the best method is
A. Arithmetical method
B. Thiessen's mean method
C. Isohyetal method
D. None of these,

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62. While calculating the average depth of annual precipitation in a catchment basin, importance to individual raingauge station is given in
A. Arithmetical method
B. Thiessen's mean method
C. Isohyetal method
D. both A and B

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63.  The rainfall at any place is described by
A. its intensity
B. its duration
C. its frequency
D. all the above.

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