摘要：Remote sensing of gravel-bed patches and resulting highresolution
digital elevation models (DEMs) allow for the identification of
various spatial scales of surface roughness. Thus far, dimensions relating to
grain and bedform roughness scales have been determined using
semivariograms or equivalent structure/autocorrelation functions. However,
it is difficult to clearly differentiate roughness scales and separate analysis
of roughness properties is not possible. This study examines the use of
moving-window detrending on gravel-patch DEMs for isolating grain and
bedform roughness and their respective topographic signatures. An
extensive dataset of water-worked gravel surfaces collected in both
laboratory and field environments is used. The measured bed topography is
separated into two distinct DEMs: one representing grains, the other
representing bedforms, and roughness properties are determined separately
for grain and bedform DEMs. The results show that both roughness scales
are controlled by the size of the coarse sediment forming the bed surface,
with positive linear relationships connecting bed composition and vertical
roughness. Coarse sediment is controlling bedform development by forming
humps on the surface, in the lee of which finer sediment is sheltered. We
present synthesis relationships connecting vertical roughness of gravel
patches to the vertical roughness of grains and bedforms.
其他摘要：Remote sensing of gravel-bed patches and resulting high-resolution digital elevation models (DEMs) allow for the identification of various spatial scales of surface roughness. Thus far, dimensions relating to grain and bedform roughness scales have been determined using semivariograms or equivalent structure/autocorrelation functions. However, it is difficult to clearly differentiate roughness scales and separate analysis of roughness properties is not possible. This study examines the use of moving-window detrending on gravel-patch DEMs for isolating grain and bedform roughness and their respective topographic signatures. An extensive dataset of water-worked gravel surfaces collected in both laboratory and field environments is used. The measured bed topography is separated into two distinct DEMs: one representing grains, the other representing bedforms, and roughness properties are determined separately for grain and bedform DEMs. The results show that both roughness scales are controlled by the size of the coarse sediment forming the bed surface, with positive linear relationships connecting bed composition and vertical roughness. Coarse sediment is controlling bedform development by forming humps on the surface, in the lee of which finer sediment is sheltered. We present synthesis relationships connecting vertical roughness of gravel patches to the vertical roughness of grains and bedforms.
