2.7.6.3 Temporal scope, hydrological response variable and receptor impact variables

The temporal scope for the ‘Non-floodplain, terrestrial GDE’ landscape group is the same as that described for the other landscape groups or combinations of landscape groups of the Galilee subregion. For groundwater variables, the reference assessment interval is defined as the 30 years preceding 2012 (i.e. 1983 to 2012). For groundwater, maximum drawdown (metres) and time to maximum drawdown are considered across the full 90-year simulation window (2013 to 2102). At the time of the qualitative modelling workshop, it was uncertain whether the time of maximum drawdown would vary in that 90-year window. Thus, the elicitation was conditioned on that variable as well.

For non-floodplain ecosystems, the qualitative modelling workshop identified one variable – groundwater – as the key hydrological component.

This hydrological variable was interpreted as two hydrological response variables that can be modelled (Table 31). The receptor impact variable was formally defined during the receptor impact modelling workshop. Annual mean percent foliage cover was chosen as the receptor impact variable. At the workshop, leaf area index was discussed as an alternative receptor impact variable but percent foliage cover was considered preferable. The relationships identified in the qualitative mathematical modelling workshop were formalised into a receptor impact model that described the response (due to changes in dmaxRef and tmaxRef) of annual average percent foliage cover of non-floodplain tree species in a 0.0025 km² (0.25 ha) area (Table 31).

Table 31 Summary of the hydrological response variables used in the receptor impact models, together with the signed digraph variables that they correspond to, for the ‘Non-floodplain, terrestrial GDE’ landscape group in the Galilee subregion zone of potential hydrological change

GDE = groundwater-dependent ecosystem