2.7.6 'Non-floodplain, terrestrial groundwater-dependent ecosystem' landscape group

Summary

The ‘Non-floodplain, terrestrial groundwater-dependent ecosystem (GDE)’ landscape group contains two landscape classes within the zone of potential hydrological change: ‘Non-floodplain, terrestrial GDE’, which occupies an area of 5.5 km²; and ‘Non-floodplain, terrestrial GDE, remnant vegetation’, which occupies an area of 1184 km². The vegetation in this landscape group depends on the subsurface expression of groundwater on a permanent or intermittent basis to maintain growth or avoid water stress and adverse impacts on condition.

The physical environment of the ‘Non-floodplain, terrestrial GDE’ landscape group is described here along with a description of vegetation assemblages and threatened flora and fauna. The water requirements and the degree of groundwater dependency of the vegetation are discussed with a focus on rooting depth and depth to watertable.

A qualitative model was developed for the ‘Non-floodplain, terrestrial GDE’ landscape group. The model focused on recruitment dynamics associated with groundwater-dependent native tree species, with the primary production associated with tree canopies providing a range of (as yet unspecified) ecosystem roles.

A receptor impact model was designed that focused on the response of mean annual percent foliage cover of woody vegetation to changes in groundwater. The quantitative modelling, based on expert elicitation of response values, indicated that the reference year had a positive effect on average percent foliage cover. This suggests that given a set of hydrological response variable values in the future, a site with higher foliage cover at the 2012 reference point is more likely to have a higher foliage cover in the future than a site with a lower foliage cover value at this reference point.

The model also indicates that the expert’s responses suggest that a 10 m groundwater drawdown will have almost no effect on average percent foliage cover.