Evaporation from flowing channels

Stability‐dependent and Dalton‐type mass transfer formulas are determined from experimental evaporation data in ambient and heated channels and are shown to have similar performance in prediction of evaporation. The formulas developed are compared with those proposed by other investigators for lakes and flowing channels. The evaporation data were obtained from a heat‐budget analysis of two large outdoor channels, one of which received ambient‐temperature water from an adjacent reservoir while the other received an artificially‐heated discharge. Daily evaporation was calculated from bihourly values of water temperature and hourly values of meteorological variables for a 63‐day study period in the summer. The evaporation data were then used to derive mass transfer evaporation formulas for heated and ambient flowing channels.