HR: 14:40h
AN: H42H-05    [PDF]
TI: Impacts of vegetation change on groundwater recharge
AU: * Bond, W J
EM: warren.bond@csiro.au
AF: CSIRO Land and Water, GPO Box 1666, Canberra, ACT 2601 Australia
AU: Verburg, K
EM: kirsten.verburg@csiro.au
AF: CSIRO Land and Water, GPO Box 1666, Canberra, ACT 2601 Australia
AU: Smith, C J
EM: chris.j.smith@csiro.au
AF: CSIRO Land and Water, GPO Box 1666, Canberra, ACT 2601 Australia
AB: Vegetation change is the accepted cause of increasing river salt concentrations and the salinisation of millions of hectares of farm land in Australia. Replacement of perennial native vegetation by annual crops and pastures following European settlement has altered the water balance causing increased groundwater recharge and mobilising the naturally saline groundwater. The Redesigning Agriculture for Australian Landscapes Program, of which the work described here is a part, was established to develop agricultural practices that are more attuned to the delicate water balance described above. Results of field measurements will be presented that contrast the water balance characteristics of native vegetation with those of conventional agricultural plants, and indicate the functional characteristics required of new agricultural practices to reduce recharge. New agricultural practices may comprise different management of current crops and pastures, or may involve introducing totally new species. In either case, long-term testing is required to examine their impact on recharge over a long enough climate record to encompass the natural variability of rainfall that is characteristic of most Australian farming regions. Field experimentation therefore needs to be complemented and extended by computer simulation. This requires a modelling approach that is more robust than conventional crop modelling because (a) it needs to be sensitive enough to predict small changes in the residual recharge term, (b) it needs to be able to simulate a variety of vegetation in different sequences, (c) it needs to be able to simulate continuously for several decades of input data, and (d) it therefore needs to be able to simulate the period between crops, which often has a critical impact on recharge. The APSIM simulation framework will be used to illustrate these issues and to explore the effect of different vegetation combinations on recharge.
DE: 1803 Anthropogenic effects
DE: 1836 Hydrologic budget (1655)
DE: 1866 Soil moisture
DE: 1875 Unsaturated zone
SC: Hydrology [H]
MN: 2003 Fall Meeting