Characterization of River Networks: A GIS Approach and Its Applications.

Fluvial geomorphology provides the basis for characterizing complex river networks and evaluating biophysical processes within watersheds. Understanding the spatial organization of morphological features, their influencing processes, and resultant geomorphic diversity in stream networks are important for efficient restoration, river health assessment, and improving our knowledge of the resilience of riverine landscapes. River characterization is a means to determine the biophysical character of river networks but many methods are fraught with pitfalls, such as the use of incorrect variables and limited acknowledgment of the hierarchical organization of rivers. In this paper, a top-down geographic information system-based approach for determining the physical typology of river networks is outlined. A suite of multivariate analyses are used to develop a nomenclature for functional process zones (FPZs) - large tracts of the river network with similar hydro-geomorphological character. Applied to the Little Miami River, Ohio, six distinct FPZs emerged, which had a nonuniform distribution along the river network. Some FPZs repeated downstream; others were rare in terms of total length and number of FPZ segments. The physical structure of the Little Miami River network was analyzed using a series of community metrics. Application of this approach for river monitoring, establishing reference conditions, as well as management of threatened and endangered species and asset trading is highlighted.