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.