Studies on Evapotranspiration of Some Aquatic Weeds

Abstract

The evapotranspiration of six dominant emersed and floating weeds was studied. Evapotranspiration of water-chestnut (Trapa natans L. var. bispinosa Roxb.), waterlettuce (Pistia stratiotes L.), and swamp morningglory (Ipomea aquatica Forsk.) did not increase water losses significantly. Evapotranspiration of waterhyacinth (Eichornia crassipes (Mart) Solms.) was 30 to 40% higher, that of narrowleaf cattail (Typha augustifolia L.) was 60 to 70% higher, and that of purple nutsedge (Cyperus rotundus L.) was 130 to 150% higher than evaporation from a free water surface under equivalent conditions. Positive correlations (significant at the 1% level) were found between some meterological factors (daily maximum air temperature and daily average wind velocity), evaporation from free water surface, and evapotranspiration from aquatic plants studied.