29.1 Evaporation from landscape
This line item represents the evaporation from landscape across the whole of the Canberra region. For 2011 the volume reported was 3,769,515 ML.
Evapotranspiration from the landscape was estimated based on the AWRA-L version 1.0.0 (Van Dijk, 2010) model outputs. Using climate grid data for the Canberra region (including precipitation, temperature and solar radiation data), AWRA-L was used to estimate the evapotranspiration depth at each gridpoint within the region. Only evapotranspiration from the landscape is considered; therefore, the surface areas of the major reservoirs and the local catchment reservoirs were excluded from the analysis. The average evapotranspiration depth across the Canberra landscape was determined as the weighted mean of evapotranspiration occurring from the relevant grid points within the region boundary. Points were weighted upon the area they represented within the Canberra landscape to remove edge effects (where the area represented is not wholly within the reporting region) and the effect of changing area represented with changing latitude. The depth of evapotranspiration was converted to a volumetric estimate by multiplying by the total area of the Canberra landscape. For the 2010–11 year, the evapotranspiration from the landscape represents 79.6% of the total precipitation on the landscape and it is 37% more than the previous year.
The gridded climate input data are subject to approximations associated with interpolating observation point data to a national grid detailed in Jones et al. (2007). The evapotranspiration estimates were subject to the assumptions of the AWRA-L model detailed in Van Dijk (2010).
Assumptions, Limitations, Caveats and Approximations
The precipitation estimates were subject to approximations associated with interpolating observation point data to a national grid detailed in Jones et al. (2007).
The uncertainty estimate was not quantified.