MEASURING RIVER-BED AND FLUME MORPHOLOGY AND PARAMETERISING B ED ROUGHNESS WITH A KODAK DCS460 DIGITAL CAMERA

Hydraulic engineers and fluvia l geomorphologists need to underst and how moving water flows over stream beds, and results in sedim ent transport. One critical aspe ct that is becoming increasingl y important is gaining knowledge about the exact shape and morphol ogy of water worked sediments. This paper demonstrates how auto mated terrain model extraction so ftware combined with images acqu ired using a Kodak DCS460 digita l camera have been effective in generating digital elevation mod els (DEMs) to represent such co mplex bed morphology and derive estimates of bed roughness. The aut omated extraction of DEMs to rep resent sedimentary forms create d in a flume requires careful ph otogrammetric design. In addition to the normal constraints impose d by scale and photo-configurati on, the estimation and stabilit y of camera inner orientation are critical. The approaches adopt ed and recommended are illustra ted by recent research projects carried out on large flumes at Loug hborough University and Hydraulics Re search, Wallingford, both in the UK. T he methodology has also been develope d and applied to a real and large braided river channel system in the Canadian Rockies, using obli que imagery acquired with the DCS 460. These three applications show the efficacy of the approach and d emonstrate that morphological da ta has been collected at signifi cantly higher spatial and tempor al densities than is possible usi ng other methods available. Autom ated digital photogrammetry now pr ovides hydraulic engineers and fluvial geomorphologists with an ability to measure at the bedfor m scale and partly at the grain scale. Manipulation of these bas e morphological descriptors and da ta derived from them, is becoming increasingly necessary for unde rstanding fully, fluvial flow an d sediment transport mechanisms.