Impact of dew deposition on water flux dynamics at a tropical rainfed paddy field in the dry season

Dew deposition and its impact on water flux dynamics at a rainfed paddy field in northern Thailand during the dry season were investigated. Daytime evaporation was found to be related to the soil water content after the paddy had been drained and to the nighttime water addition after the paddy soil surface strongly dried. Consequently, daytime evaporation decreased because of nighttime dew deposition ceased due to increased soil surface temperature. Thus, daytime evaporation from rainfed paddy fields appears to be controlled by the timing of paddy water discharge and dew deposition. This finding differs from earlier studies in arid and semiarid regions that showed that the dew deposition on a bare soil surface is probably rare because the dew-point temperature is lower than the soil surface temperature due to the lack of water vapor content (WVC) in the atmosphere. This result indicates that atmospheric WVC might play a key role in water addition to the soil and water flux dynamics in the tropics.