HR: 1330h
AN: H13B-10    [Abstracts]
TI: How do Sandy Palaeochannels Affect Shallow Groundwater Flow in a Clay-Dominated Vadose Zone under Flood Irrigation?
AU: * Vanags, C P
EM: cvanags@student.usyd.edu.au
AF: The University of Sydney, A03 Ross Street Building The University of Sydney, Sydney, NSW 2006 Australia
AU: Vervoort, R W
EM: w.vervoort@acss.usyd.edu.au
AF: The University of Sydney, A03 Ross Street Building The University of Sydney, Sydney, NSW 2006 Australia
AB: Palaeochannels, or prior streams, are common landscape features in much of the irrigated areas of the Northern Murray-Darling Basin, Australia. Prior research has indicated that these features are likely to amplify irrigation water losses due to their sandier textures. However, little is known about the pathways and flux of this water after it infiltrates and how changes in soil properties and sedimentary layering govern this movement. This poster utilises electromagnetic induction surveys to supplement soil core information to model a palaeochannel system using the three-dimensional groundwater simulation package PMWIN-MODFLOW. Hydraulic properties were estimated using pedotransfer functions of soil physical properties. Based on the distribution of observed soil properties and the uncertainties related to the hydraulic property estimation, several realisations were created and Monte Carlo-type simulations were run to identify model sensitivities to the empirically-derived input parameters. Irrigation and rainfall top boundary inputs were applied to simulate water movement through the system. Model outputs are analysed using simulated observation wells and particle tracing, showing perched water tables within the sandy palaeochannel following stress periods. Contrasts in hydraulic conductivity, soil layering, and slope of the channel had a greater effect on water movement under irrigation than under natural rainfall conditions.
DE: 1875 Unsaturated zone
DE: 1894 Instruments and techniques
DE: 3210 Modeling
DE: 9330 Australia
SC: Hydrology [H]
MN: 2005 Joint Assembly