HR: 14:55h
AN: H42H-06    [PDF]
TI: The Impacts of Vegetation Change on Regional Groundwater Balances - an Australian Perspective
AU: * Gilfedder, M
EM: mat.gilfedder@csiro.au
AF: CSIRO Land and Water, GPO Box 1666, Canberra, ACT 2601 Australia
AU: Walker, G R
EM: glen.walker@csiro.au
AF: CSIRO Land and Water, PMB 2, Glen Osmond, SA 5064 Australia
AU: Dawes, W R
EM: warrick.dawes@csiro.au
AF: CSIRO Land and Water, GPO Box 1666, Canberra, ACT 2601 Australia
AB: Salinity in the Australian landscape is in many cases a groundwater issue. The removal of deep-rooted native vegetation and its replacement with cropping/grazing systems has increased groundwater recharge across large regions in many regions [Walker et al., 1999]. As groundwater is already saline in many areas, this has led to expanding areas of waterlogged/saline land, and increased discharge of salt to streams. The ability to predict the timing and magnitude of the groundwater response to vegetation change is desirable. Unfortunately, groundwater data is very sparse across large areas of Australia. While complex-models can be used successfully for specific point-source problems at a local-scale, the paucity of data at a regional scale begs for a simpler approach using broadly available spatial data. Such an approach is analogous to the prediction of flows in ungauged surface water catchments with almost no neighbouring historic gauging data. In broad terms the available data consists of limited bore-data (often sparse in non-irrigated areas), historical stream flow and salinity data (used to infer salinity trends and catchment salt balances), particular individual case study catchments, as well as recently developed Groundwater Flow Systems (GFS) maps which disaggregate the landscape into broad geomorphic / hydrogeological units. We present an Australian perspective on simple methods for predicting catchment response to vegetation change. These include the use of GFS maps, building on the surface water balance work of Zhang et al. [2001], and developing simple groundwater response functions to provide prioritisation tools for predicting the effect of vegetation change on the groundwater balance across large areas. References Walker G.R., M. Gilfedder, and J. Williams, Effectiveness of Current Farming Systems in the Control of Dryland Salinity, CSIRO Land and Water: Canberra, 1999. (www.clw.csiro.au/publications/Dryland.pdf) Zhang, L., W. R. Dawes, and G. R. Walker, The response of mean annual evapotranspiration to vegetation changes at catchment scale, Water Resour. Res., 37, 701-708, 2001.
DE: 1829 Groundwater hydrology
DE: 9330 Australia
SC: Hydrology [H]
MN: 2003 Fall Meeting