Hydrogeomorphic zones characterize riverbed sediment patterns within a river network

Abstract

Simplified techniques for assessing the condition of aquatic ecosystems are widely used at multiple levels of investigation. Tools for the rapid characterization of the physical structure of river systems at the entire network scale are limited. Functional Process Zones (FPZs) are remotely-derived river sectors representing different hydrogeomorphic and ecological perspectives of river networks. Here we investigate associations between FPZs and the composition of 3500 field-derived riverbed sediment samples for the Kanawha River Basin, USA. Using various statistical analyses, we confirmed the texture of the riverbed substratum differed between FPZs of the Kanawha River. Catchment geology and valley floor width, surrogates for sediment supply and overbank hydraulic conditions, respectively, were signifi cant factors associated with textural differences in riverbed substratum between FPZs. Self-emergent groups of riverbed sediments, derived independently via Entropy analysis, agreed with the a priori FPZ classification approximately 70 percent of the time. We demonstrate that rapid assessment of riverbed sediments can be undertaken through an initial analysis of FPZs within a stream network. FPZs can be generated with remotely sensed data and can account for variability in riverbed sediments at a basin scale thereby contributing to management activities including bioassessment, monitoring, restoration, impact identification, and characterization for environmental flows programs.