Estimation of evaporation from non-vegetated surfaces using natural deuterium

Abstract

Loss of water by evaporation from bare surfaces is difficult to measure, because, like transpiration, it is subject to the vagaries of climate and water potential. Such loss can be a dominant parameter in the water balance of arid or semi-arid areas. Classical soil physical and meteorological methods can be used to estimate evaporative fluxes over short time periods, but are difficult to use over the longer times which are appropriate for most water balance studies. We describe here a new method for the estimation of evaporation from a bare surface based on enrichment of natural deuterium. The advantage of this technique is that it provides an integrated measure over relatively long periods of time. Using this method on data collected from the bed of Lake Frome, a normally dry salt lake in Central Australia, we find that the evaporation rate from the ‘dry’ lake surface is 63 mm yr−1.