Hydrology and Earth System Sciences www.hydrol-earth-syst-sci.net 1027-5606 1607-7938 7 1 2003 10.5194/hess-7-11-2003 http://www.hydrol-earth-syst-sci.net/7/11/2003/ http://www.hydrol-earth-syst-sci.net/7/11/2003/hess-7-11-2003.html http://www.hydrol-earth-syst-sci.net/7/11/2003/hess-7-11-2003.pdf 11 21 0000-00-00 Evaporation characteristics of wetlands: experience from a wetgrassland and a reedbed using eddy correlation measurements M. C. Acreman R. J. Harding C. R. Lloyd D. D. McNeil Centre for Ecology and Hydrology, Wallingford, OX10 8BB, UK Email for corresponding author: man@ceh.ac.uk Measurements of evaporation were made from July to November 1999 using the eddy correlation method on two wetland types – wet grassland and reedbeds – in south west England. The evaporative water use of a reed bed exceeded that of the grassland wetland by 15% (or 50 mm over the 5 months). The evaporation rates at both sites exceed of the Penman Potential Evaporation estimates calculated for this area. The difference between sites results from the higher roughness length of the reed bed and the lower effective surface resistance of the reed/open water assemblage. At the grassland site, a significant relationship between the surface resistance and water table level has been demonstrated. The water table at this site is managed to maintain the plant diversity and allow some agricultural access. This regime specifies a water table below the surface during the summer period, which results in higher surface resistances and lower evaporation. The results have important implications for local water resources management, especially where wetlands are maintained by pumping from rivers or groundwater.</p> <p style="line-height: 20px;"><b>Keywords: </b>wetlands, evaporation, eddy correlation, wet grassland, reedbed, vapour pressure, water table level</p>