Oral Presentation Australasian Groundwater Conference 2017

Groundwater dynamics in upland catchments of NSW (242)

Tony Bernardi 1 , Leah Moore 2 , David Mitchell 1
  1. NSW Department of Primary Industries, Orange, NSW, Australia
  2. University of Canberra, Canberra, ACT, Australia

The Key Sites research analyses how natural landscape processes, including land and water salinisation, are impacted by changes in landuse and climate.

Eight long term monitoring sites were established across NSW in a north-south transect from Quirindi in the north to Wagga Wagga in the south in 2002-2003. The sites are located in first and second order upland sub-catchments, with some undergoing landuse change from annual crop and pasture to perennial pastures and trees. A range of components of the hydrological cycle including climate and groundwater were measured.

Analysis of monthly groundwater data from 2003 on 71 boreholes across all sites using the auto-regressive model HARTT (Hydrograph Analysis: Rainfall and Time Trend) was conducted.  There was a relationship between changes in groundwater level and rainfall that varied on a continuum from high (R2 0.80 – 0.97; n=31) through to low (R2 <0.50; n=6) across the sites.  

The calculated lag time between rainfall and groundwater response varied from less than 1 month to 46 months, with most highly responsive (1 month or less (n= 62)). The underlying trend is for the groundwater to fall from 14 to 360 mm/year in 51 boreholes (P<0.05) and rise from 16 to 189 mm/year in 10 boreholes (P<0.05). The underlying trend in the other 10 boreholes was small (P>0.05).

Rainfall was the major driver in the rise and fall of groundwater across all sites. This challenges the paradigm that the removal of deep rooted vegetation is the primary driver responsible for the rise in groundwater and the consequential mobilisation of salts stored deep in the profile in upland catchments.  

  • We are offering awards for Career and Early Career presentations and posters. Please indicate length of time since highest degree completed.: 5 Years or more
  • We are offering awards for Career and Early Career presentations and posters. Please indicate length of time since highest degree completed.: 5 Years or more