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Classification of the Tasmanian Continental Shelf using multivariate analysis of wave, tide and sediment parameters. R. Porter-Smith, P. T. Harris, A. D. Heap, O. Anderson, R. Coleman, D. Greenslade , C.J. Jenkins and P. McQuillan. 01/0000. Talk Structure Reasons Approach
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Classification of the Tasmanian Continental Shelf using multivariate analysis of wave, tide and sediment parameters R. Porter-Smith, P. T. Harris, A. D. Heap, O. Anderson, R. Coleman, D. Greenslade ,C.J. Jenkins and P. McQuillan 01/0000
Talk Structure Reasons Approach Physical variables Analytical proceedure Results Conclusions Future goals
Why….? • Develops an automated quantitative regionalisation. • Provides a spatial representation. • Fulfils a need for greater accuracy. • Promotes efficient assimilation of large complex datasets.
CBS Central Depth varies from 80 to Bass Strait 50m. Subtrate mainly mud. FLI Flinders Strong tidal currents. Waves highly variable. FRA Franklin Extremely exposed. Moderate tidal range. OTW Otway Very steep off-shore gradients. High wave energy. TWO Twofold Moderate tidal range. Shelf Variable wave energy. Interim Marine and Coastal Regionalisation for Australia - a qualitative ecosystem-based classification
Distances between Pairs of Combined Classes (in the sequence of merging)
carbonate mud tide-v bathy grain-size wv-ht sorting wv-prd Ordination of 500 sample sites based on 8 Physical Variables. (Semi-strong hybrid multi-dimensional scaling using the Bray-Curtis similarity measure. Data standardised to zero mean and unit variance. Stress in 3 dimensions = 0.118)
Principle Components Analysis of 100 random sample sites based on 8 Physical Variables.
Variables Correlation wave-height 0.948 1 carbonate 0.946 2 wave-period 0.908 3 mud 0.832 4 bathymetry 0.794 5 sorting 0.688 6 tidal-velocity 0.583 7 grainsize 0.496 8 *Monte Carlo analysis -all variables significant at 99% confidence
Shallow water, with variable wave energy, strong local tidal Class 1 currents and a terrigeneous, mixed grained sediment. Shallow water, with variable wave energy, strong local tidal Class 2 currents and a calcareous, mixed grained sediment. Moderate water depth, with high wave energy, strong tidal Class 3 currents and a calcareous well- sorted sediment. Deep water, very high wave energy, moderate tidal currents Class 4 and a calcareous well-sorted sediment. Deep water, with low wave energy, low tidal currents, and Class 5 a fine, muddy, mixed grained, calcareous sediment. Final Classification
Conclusions • Allows a rigorous interrogation of available data • Helps solve a class problem - tests robustness • An alternative to the Delphic (qualitative) approach • Framework of spatial classes for environmental management
Future goals • Improve the methodology • Refine current datasets • Examine other Physical Variables • Bring in a biological component • Examine annual/seasonal variability