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University of Adelaide (1999)

Potential impacts of interception belts on the management of dryland salinity

Taylor, Peter John

Titre : Potential impacts of interception belts on the management of dryland salinity

Auteur : Taylor, Peter John

Grade : Doctor of Philosophy (Ph.D.) 1999

Université de soutenance : University of Adelaide,

Résumé
"The extent and rate of increase of dryland salinity are serious problems, with many environmental, economic and social ramifications. For the Upper South East catchment of South Australia, an Environmental Impact Study in 1993 recommended the implementation of a revegetation program, with a high priority option the strategic use of interception belts of trees. For this work, it was hypothesised that interception belts would be useful land management tools for sustainable control of dryland salinity. The main aims were to establish if interception belts could control rising groundwater, where in the landscape they should be planted and what configuration they should take. At a red gum salinity trial site, spatial and temporal transpiration patterns of Eucalyptus camaldulensis (Lake Albacutya provenance) were examined using the heat pulse velocity technique and the stable isotopes of water. Soil and groundwater conditions were monitored. Shorter term monitoring of intra and inter-provenance variability of transpiration was carried out. At a trial blue gum (E. globulus) plantation, edge effects due to increased wind advection on transpiration rates were investigated. Red gum transpiration varied between 0.13 and 4.2 times rainfall in summer and autumn and was approximately equal to rainfall at other times. Significant differences in water use, normalised to sapwood area, were found among trees along the saline gradient. Trees utilised groundwater for approximately half the year. In the blue gum plantation, edge trees showed higher normalised water use compared to inner trees when canopy conductance exceeded critical values. Effects were no evident when water availability became limiting. Optimal locations for interception belts are suggested where groundwater is accessible and strong gorundwater gradients for lateral leaching of salt exist. Size of belts depends on recharge zone size and recharge depth. In the Upper South East catchment, between 10,000 and 20,000 ha of interception belts would be needed to eliminate recharge from the dunes. Use of existing GIS datasets would enable calculation of precise lengths of belts required and thus necessary widths. It is concluded that interception belts will be useful tools in the management of dryland salinity. Further study should examine performance of interception belts in finer scale groundwater models as well as in existing regional or more complex ecosystem process models

Mots clés : Salinity Control South Australia

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