Projected climate change effects on diffuse recharge in the NT - Summary for major groundwater resources
Details:
Title
Projected climate change effects on diffuse recharge in the NT - Summary for major groundwater resources,
Creator
Short, Michael, A.,
Northern Territory. Department of Environment and Natural Resources,
Collection
E-Publications,
E-Books,
PublicationNT,
23/2018,
Date
2019-03-01,
Description
The purpose of this report is to summarise the CSIRO recharge modelling results as they apply to major NT groundwater resources. The aim is not to provide a detailed synthesis of the modelling methods (this can be found in the CSIRO reports and academic publications) but to provide a discussion on the
modelling results and likelihood for future climate change effects on NT’s groundwater systems. The
report will summarise the following points:
• modelled recharge scaling-factors across the NT;
• probability of exceeding a range of recharge scaling-factors across the NT; and
• general implications for NT groundwater allocation planning.
A key concept to note for the application of the CSIRO modelling to groundwater resources in the NT, is
that the modelling considered diffuse recharge only - that is, recharge to aquifers via deep drainage
through the root zone and unsaturated soil profile to the watertable. Although many of the NT’s aquifers
receive most of their recharge by this mechanism, many of the NT’s carbonate aquifers may also receive
recharge via point source recharge mechanisms during high-intensity tropical weather events (e.g.
cyclones and tropical storms). Point source recharge rapidly reaches the saturated zone by bypassing
the root zone and soil profile through karstic landscape features, especially where carbonate formations
outcrop at the ground surface.
Another mechanism of point recharge that is relevant to water resources in the NT is via episodic
streamflow events. This is particularly relevant for shallow aquifers in the arid southern regions where
infrequent streamflow events (sometimes decadal intervals or more) from typically dry streambeds are
the only significant source of modern recharge.
These recharge mechanisms are not considered by the CSIRO modelling and interpretation of the
following results should consider this potential limitation of the modelling.
Also note that the Crosbie et al. (2013) modelling did not include the Tiwi Islands but the values are
expected to be very similar to those described for the Darwin Rural Area WCD.,
Notes
Made available via the Publications (Legal Deposit) Act 2004 (NT).,