A nested hierarchical perspective to enhance interpretations and communication in fluvial geomorphology for use in water resources management: Lessons from the Okavango Delta, Botswana

Abstract

A key skill that geomorphologists possess is the ability to use multi‐scale perspectives in their interpretations of landscapes. One way to gain these perspectives is with the use of nested hierarchical frameworks. In fluvial geomorphology, such frameworks help with assessment of large‐scale controls (e.g., tectonic activity, climate change) on the pattern and dynamics of smaller‐scale physical features (e.g., channels, floodplains, bars), and conversely illustrate how these smaller‐scale features provide the building blocks from which to make interpretations of fluvial processes and dynamics over larger spatial and temporal scales. Given the rapid pace of technological developments, the range of relatively inexpensive tools available for visualising and mapping landscapes at different spatial scales is expanding exponentially. In this paper, which focuses on the World Heritage‐listed Okavango Delta in Botswana, we demonstrate how various visualisations generated by different technologies at different spatial scales (catchment, landscape unit, reach, site and geomorphic unit) are providing critical baseline information to enhance interpretation and communication of fluvial geomorphology, with potential application in water resources management. In particular, our nested hierarchical approach could be used as an interactive communication tool for non‐specialists and embedded within existing and future management plans for the Delta. The construction of nested hierarchies that synthesise information and analyses can be a valuable addition to the environmental manager's toolkit.

Things we can do now that we could not do before: Developing and using a cross-scalar, state-wide database to support geomorphologically-informed river management

“…Hence, a generic, carefully scaffolded approach was designed to derive a coherent package of catchment-specific geomorphic information, relating process-based insights that can be applied to all rivers, everywhere [ 11 , 24 , 56 ]. Data and analyses are conducted within a hierarchical, cross-scalar framework [ 24 , 57 , 58 ]. Systematic approaches to data collection are used to explain spatial variability in geomorphic river character, behaviour, pattern, condition and recovery.…”

Product vs. process? The role of geomorphology in wetland characterization

“…In geomorphological riverine classificatione.g. using the River Styles Framework (Brierley and Fryirs, 2005)a hierarchy is established by organizing larger-scaled controls, usually starting at the catchment scale, over progressively smaller-scaled features (Fryirs et al, 2018). Crucially, geomorphological hierarchies, like geomorphological concepts, are bidirectional.…”

“…Crucially, geomorphological hierarchies, like geomorphological concepts, are bidirectional. While larger-scale controls influence the dynamics of smaller-scaled features, smaller-scaled features are, in turn, the 'building blocks' that influence processes over larger spatiotemporal scales ( Figure 3B) (Werner, 2003;Thoms et al, 2007;Fryirs et al, 2018). For example, catchment-scale sediment connectivity is dependent on connectivity between landscape compartments and individual channel reaches, and while connectivity potential may be established, sediment transfer is dependent on sediment availability from individual landforms throughout the catchment (Fryirs, 2013;.…”

To plug‐in or not to plug‐in? Geomorphic analysis of rivers using the River Styles Framework in an era of big data acquisition and automation

“…Both approaches are vital; indeed, they are complementary. A revolution in practice in monitoring and measurement techniques is transforming data availability and approaches to analysis within earth and environmental sciences (Fryirs et al, ; Passalacqua et al, ; Piégay, Kondolf, Minear, & Vaudor, 2015).…”

“…In parallel, recent decades have also seen the emergence of a number of riverscape interpretation frameworks; that document the geomorphic (or hydromorphic) context of a river system. These include classification and characterization frameworks, nested hierarchical frameworks, and habitat assessment frameworks (Belletti, Rinaldi, Buijse, Gurnell, & Mosselman, ; G. J. Brierley & Fryirs, ; Fryirs et al, ; Gurnell et al, ; Kasprak et al, ). Typically these frameworks have, at their core, a conceptual structure and sequence of activities/steps that build layers of evidence, analysis and interpretation about riverscapes.…”