Characterization of River Networks: A GIS Approach and Its Applications

Abstract

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.

Functional process zones and their fish communities in temperate Andean river networks

“…Accordingly, the physical structure of river networks govern the type, abundance, and arrangement of biological communities found within these networks (cf. Thoms et al, ). This study has shown each FPZ in the Biobío River to have a unique fish community, similarly to specific macroinvertebrate communities and aquatic food web associated with FPZs character (Maasri et al, ; Thoms et al, ).…”

“…The river networks of the Biobío and Imperial rivers were obtained from the Chilean National Hydrography data set, which provides a 1:50.000‐scale digital representation. The river network of each system was divided into 5‐km reaches following the approach recommended by Thoms et al (). Each reach defined a site and 160 sites were defined in the Biobío River and 187 in Imperial River.…”

“…On the basis of the results of cluster analysis, groups of reaches were selected. The criterion of selection was based on the inflexion point in the curve of relationship between the number of groups in the cluster and their corresponding similarity value (Thoms et al, ). Once identified, similar groups were arrayed onto the streamlines of the Biobío and Imperial Rivers to delineate the position of reaches with similar morphological character.…”

“…River systems display unique and emergent properties relevant to the scale of analysis. Hence, the structure and function at higher levels of organization (e.g., entire river networks) cannot be obtained from the summation of individual components at lower levels of organization (e.g., individual reaches; Allen & Starr, ; Thoms, Scown, & Flotemersch, ).…”

Looking Back at 2018

“…); Identifying the relative importance of water quality stressors in predicting fish community responses in midwestern streams (Meador and Frey ); Using geographic information system and multivariate statistical methods to characterize river networks for establishing reference conditions and managing threatened and endangered species (Thoms et al. ); Addressing social dimensions of urban flood exposure concerns (Hale et al. ); and How snowpack melt‐out timing correlates with agricultural droughts (Nicholson et al.…”