Recent research in fluvial geomorphology has emphasized the spatially
distributed feedbacks amongst river channel topography, flow hydraulics
and sediment transport. Although understanding of the behaviour of
dynamic river channels has been increased markedly through detailed
within-channel process studies, less attention has been given to the
accurate monitoring and terrain modelling of river channel form using
three-dimensional measurements. However, such information is useful in
two distinct senses. Firstly, it is one of the necessary boundary
conditions for a physically based, deterministic modelling approach in
which three-dimensional topography and river discharge drive
within-channel flow hydraulics and ultimately spatial patterns of
erosion and deposition and therefore channel change. Secondly, research
has shown that an alternative means of estimating the medium-term
bedload transport rate can be based upon monitoring spatial patterns of
erosion and deposition within the river channel. This paper presents a
detailed assessment of the distributed monitoring and terrain modelling
of river bed topography using a technique that combines rigorous
analytical photogrammetry with rapid ground survey. The availability of
increasingly sophisticated terrain modelling packages developed for
civil engineering application allows the representation of topographic
information as a landform surface. Intercomparison of landform surfaces
allows visualization and quantification of spatial patterns of erosion
and deposition. A detailed assessment is undertaken of the quality of
the morphological information acquired. This allow some general
comments to be made concerning the use of more traditional methods to
monitor and represent small-scale river channel morphology.