A hybrid method for size characterization of coarse subsurface fluvial sediments

This paper introduces and evaluates a novel method for ascertaining the grain-size distribution of subsurface sediments that involves profoundly less sampling effort than standard methods. It is based on hybrid sampling principles previously applied to the construction of synthetic surface grain-size distributions. The method is developed from an empirical demonstration of the approximate similarity of surface and subsurface grain-size distributions when compared over a common range of sizes. Subsurface hybrid models are found to provide good facsimiles of grain-size distributions defined using standard criteria and to yield distribution percentiles with millimetre accuracy. The technique is presented as an expedient alternative to standard methods for large, perennial gravel-bed rivers. As this is a new technique, prudent application is advised in lieu of further investigation. Copyright (C) 2004 John Wiley Sons, Ltd.