Comparative of influences of light intensity and wind velocity on the evaporation rate of saturated soil surface

Abstract

The evaporation rate of saturated soil was investigated. The evaporation pan (Class A) was setup in a laboratoryscale
experiments. The effects of varying light intensity from 0 to 1,000 W·m-2 and wind velocity from 0.53 to 1.82
m·s-1 on the evaporation rate were investigated. It was found that light intensity plays an important role in the
evaporation rate. The evaporation rate increased from 6. 08x10-5 to 11. 6x10-5 m·min-1 when the light intensity
increased from 0 to 1,000 W·m-2 because the convective mass transfer coefficients were increased due to the
decrease in vapor pressure difference between the water surface and air, while evaporation increased from 9.93x10-5
to 13. 20x10-5 m·min-1 when the wind velocity increased from 0. 53 to 1. 82 m·s-1 because the convective mass
transfer coefficients were increased due to the high temperature difference between the air and water surface. On the
other hand, when light intensity decreased 0. 95% from 1,000 to 990. 52 W·m-2 caused the evaporation rate to
decrease 0.0523x10-5 m·min-1 from 11.66x10-5 to 11.55x10-5 m·min-1 or 0.45% . While wind velocity decreased
0.25% from 1.82 to 1.81 m·s-1, the evaporation rate decreased 0.0117x10-5 m·min-1 from 13.20x10-5 to 13.19x10-5
m·min-1 or 0.089%. When compare to the actual data during the years 2008 to 2017, light intensity decreased 0.95%
from 423. 66 to 419. 68 W·m-2 caused the evaporation rate to decrease 0. 0187 mm from 4. 351 to 4. 332 mm or
0.432%. While the wind velocity decreased 0.25% from 6.041 to 6.026 m·s-1 caused the evaporation rate to decrease
0. 001 mm from 4. 351 to 4. 350 mm or 0. 023% . Thus, light intensity has influence on the evaporation rate by
accounting for 95.01% of decrease in the evaporation rate and the wind velocity has influence on the evaporation
rate by accounting for 4.99% of decrease in the evaporation rate.