Empirical Evaporation Equations

Q. If the wind velocity at a height of 9 m is measured as 50 km/h, the velocity at a height of 0.5 m above the ground can be expected to be, in km/h about

1. 18
2. 28
3. 33
4. 43

Q. Which of the following empirical methods/formulae can be used to estimate the evaporation loss from a water course?

i) Muskingum formula

ii) Mayer's formula

iii) Fitzgerald's formula

iv) Thiem's formula

1. (i) and (ii)
2. (i) and (iv)
3. (ii) and (iii)
4. (iii) and (iv)

Q. A deep reservoir had the following average values of climatic parameters during a week:
(i) Saturation vapour pressure = 17.54 mm Hg
(ii) Relative humidity = 50%
(iii) Wind velocity at 1.0 m above ground surface = 16 kmph
An ISI standard pan at the site has pan coefficient 0.80. If this pan indicates an evaporation of 70 mm in a week, estimate the error in the result of Meyer's method relative to pan evaporation measurements.
$[\text{Take}{k}_m=0.36]$

1. 11%
2. 4.6%
3. 6.5%
4. 9%