Hyperscale Modelling of Braided Rivers: linking morphology, sedimentology and sediment transport

Abstract

A time-series of very high resolution digital elevation models (DEMs) of a braided reach of the Rees River, NZ were derived from a novel combination of mobile terrestrial laser scanning (TLS) and image analysis of non-metric aerial photography. In total 10 DEMs were generated from surveys undertaken between October 2009 and May 2010 and used to quantify the 3D morphodynamics of the Rees River. The surveys involved between 86-356 individual laser scans that were acquired using a Leica HDS6100 high-frequency TLS while the braidplain was exposed at low flow. Scans were co-registered and georeferenced using a mobile network of targets positioned using RTK GPS. The unified point clouds incorporated over 4 x 109 raw 3D observations, with a median point density of 1600 pts m-2. Continuous topographic models of the braidplain were generated by fusing these data with empirical-optical depth maps of submerged areas of the reach, derived from calibrated, geo-referenced, helicopter aerial photography. DEMs and derived products were extracted from this combined product at resolutions ranging from 0.1-1 m resolutions, providing unparalleled information on the morphology, sedimentology and dynamics of braided rivers.