Using multivariate statistical techniques to interpret patterns of flood plain sedimentation

Interpretation of flood plain sedimentation often relies on qualitative evaluations. Quantitative analysis is often made difficult by large amounts of data generated through an array of physical and chemical measurements of sediment character. As such, analysis of sediment character is mostly focused on bivariate comparisons. This paper illustrates the utility of multivariate statistical techniques in the interpretation of flood plain sedimentation, which consider multiple factors simultaneously. Seventeen sediment characteristics were used to distinguish between groups of sediment samples collected from the lower Balonne flood plain in southwest Queensland, Australia. Sediment samples were analysed in a hierarchical manner according to a nested design of river, zone and geomorphic unit scales. The analyses demonstrated differences in sediment character at the river scale. Clear patterns in sediment character were noted at the zone and geomorphic units scales, although these were river-specific. Techniques used in this study can rapidly divide the flood plain into units based on similarities in sediment character, and can provide greater quantitative interpretations of flood plain sedimentation.