EVAPORATION FROM DAMPLAND VEGETATION ON A GROUNDWATER MOUND

Annual evaporation from an area of wetland vegetation in a dampland on a groundwater mound near Perth, Western Australia, was estimated from measurements of daily evaporation using ventilated chambers on thirteen occasions between March 1987 and March 1988. Evaporation over this period was estimated to be 814 mm, which exceeded the annual rainfall (747 mm) by 67 mm of water. Groundwater loss during summer was 266 mm of water (equivalent to 35% of annual rainfall). During summer, estimates of daily evaporation using diurnal water-table fluctuations gave values which were highly correlated (r = 0.90) with the ventilated chamber method. Provided that estimation was restricted to periods when vegetation is drawing mainly on groundwater, the diurnal fluctuation method offers a practical, cheap alternative method of estimating evaporation from wetlands. © 1990.