Geomorphic heterogeneity as a framework for assessing river corridor processes and characteristics

Abstract

Spatial and temporal heterogeneity, or messiness, is a broadly desirable characteristic of river corridors and an indicator of many of the geomorphic processes that sustain fluvial ecosystems. However, quantifying geomorphic heterogeneity is complicated by a lack of consistent metrics, classification schemas for dividing the river corridor

Quantifying floodplain heterogeneity with field observation, remote sensing, and landscape ecology: Methods and metrics

“…We specifically did not to pre‐define floodplain classes (“field classes” and “field patches”) as we did not want to limit the types of classes to what we saw during the pilot study (Wohl & Iskin, 2019). The pilot was conducted only on Colorado mountain stream floodplains, and we wanted the field classes in this study to reflect each unique site (Scott et al, 2022).…”

“…Classic descriptions of landscapes are segmented into landscapes, classes, and patches (“patch‐based”, Figure 2), and the spatial metrics are consequently grouped by landscape‐scale, class‐scale, and patch‐scale metrics. Although there are other types of analyses in landscape ecology beyond patch‐based (Erős & Lowe, 2019; With, 2019), we have chosen to use patch‐based, following Scott et al (2022), landscape‐scale metrics in this study to simplify the methods and to facilitate comparison between floodplains at the reach scale (here, a reach is a length of river corridor with consistent channel and valley geometry). More detailed analysis of specific classes could use class‐ or patch‐scale metrics.…”

“…Heterogeneity, complexity, connectivity, diversity, and other terms are used to describe related facets of temporal and spatial variation characteristic of river corridors (Table 1). Different methods have been used to measure floodplain variations, typically with the intent of inferring underlying processes (Scott et al, 2022; Turner & Chapin III, 2005).…”

Widespread Wood Placement and Regrading Drive Lateral Connectivity and Reworking of the Channel and Floodplain in a Valley Bottom Reset to Stage 0

“…Here, I present 6 years of monitoring of restoration to Stage 0 along Deer Creek. I analyze the spatial arrangement and change of geomorphic units across the valley bottom using a geomorphic heterogeneity framework (Scott et al, 2022) to quantify how different phases of restoration set up the valley bottom's geomorphic response to subsequent high flows. By mixing quantitative analysis of geomorphic spatial and temporal heterogeneity and qualitative observations of the spatial correlation between wood and geomorphic change, I examine how wood rearrangement alters the lateral connectivity of water and sediment and reworking of both the channel and floodplain.…”

“…To characterize the geomorphic form of the site and infer geomorphic process activity, I applied a geomorphic heterogeneity framework (Scott et al, 2022), focusing on the diversity (evenness and richness) and spatial configuration (namely fragmentation) of geomorphic units. This framework relies on mapping the wall-to-wall extent of geomorphic units across the valley bottom that indicate relevant forms (in this case, those that define a multi-channel riverscape and indicate lateral connectivity) and processes (in this case, avulsion and local scour and deposition around wood).…”