Reading the Landscape

Reading the Landscape

“The ultimate test of geomorphological knowledge lies in field interpretation of real world examples.”

In simple terms, geomorphology is the scientific study of the characteristics, origin and evolution of landscapes. Geomorphic enquiry entails the description and explanation of landscape forms, processes and genesis. Implicitly, therefore, it requires both a generic understanding of the physics and mechanics of process and an appreciation of the dynamic behaviour of landscapes as they evolve through time. The key to effective use of geomorphic knowledge is the capacity to place site-specific insights and relationships in their broader landscape context, framing contemporary process-form linkages in relation to historical imprints. Theoretical and modelling advances are pivotal in the development and testing of our understanding. However, the ultimate test of geomorphological knowledge lies in field interpretation of real world examples.

Landscapes determine the template upon which a range of biophysical processes interacts. Alterations to the geomorphic structure of rivers have enormous implications for the operation of biophysical fluxes that affect the movement of water, sediment, nutrients, etc. Hence, a geomorphic template provides a basis for ‘whole of system’ thinking, aiding the development of coherent plans and strategies for environmental management, guiding decision-making for concerns relating to global change, natural resource management, natural hazards, or conservation and rehabilitation issues.

Reading the landscape is a mechanism by which practitioners use their knowledge and experience to identify the assemblage of landforms or features that make up rivers, develop hypotheses to interpret the processes responsible for those landforms, determine how those features have/will adjust and change over time, and finally place this understanding in its spatial and temporal context. Successful interpretations draw on existing theory, questioning and testing its relevance to the system under investigation.

The constructivist (building block) approach to “Reading the Landscape” that is utilised in the River Styles® framework assesses how each part of a system relates to its whole in both spatial and temporal terms (Figure 1). As a fluvial geomorphologist, a range of different questions are asked and answered when “Reading the Landscape”.

Figure 1. Click to see full-size.

An approach to reading the landscape

Step One: Identify individual landforms (geomorphic units) and the process-form relationships that determine their process regime
Identify the types of units in the channel and on the floodplain. Interpret the morphodynamics of each geomorphic unit based upon its process-form interactions, outlining the erosional and depositional processes that create and rework each feature.
Step Three: Explain controls on the package and assemblage of landforms at the reach-scale and how they adjust over time
Analyse the range of flux and imposed boundary conditions that control the process relationships that characterize the behavioural regime of a reach. Assess natural (geological, climatic) and human-induced controls upon river behaviour and evolution. Explain contemporary landscape behaviour in relation to longer-term evolution, framing system responses to human disturbance in relation to natural variability.
Step Two: Analyse and interpret the package and assemblage of landforms at the reach-scale and how they adjust over time
Analyse the range of units within a reach as packages of genetically linked assemblages, taking into account their position and their juxtaposition with other units. Appraise interactions between landforms by interpreting the erosional or depositional nature of boundaries (contacts) between units. Assess magnitude-frequency relationships that form and rework the package of landforms. These insights are combined to determine the behavioural regime (natural range of variability) of the reach.
Step Four: Integrate understandings of geomorphic relationships at the catchment scale
Place each reach/site in its catchment context and examine linkages between compartments to interpret spatial relationships within that system. Examine downstream patterns of river types to assess why certain rivers occur where they do along longitudinal profiles, interpreting the dominant controls on river character and behaviour. Interpreting the efficiency and effectiveness of sediment flux at the catchment scale determines the strength of linkages (connectivity) in the catchment, and associated natural or human-induced responses to disturbance events (i.e. lagged and offsite impacts).
Reading the landscape is an open-ended, interpretative, field-based approach to geomorphic analysis of river systems. Efforts to read the landscape can be summarised as follows:
Identify features and assess their formative processes
Appraise how these features fit together in a landscape (reaches and catchments)
Assess how these features adjust and evolve over time

 

Meaningful identification and description underpins effective explanation, providing a platform with which to make realistic predictions about likely future states. Landscape relationships are analysed through appreciation of system dynamics, recognising the variable imprint/memory of influences from the past. Behavioural regimes are differentiated from river changes as landscapes evolve. Human impacts upon rivers are differentiated from natural variability. The book, “Geomorphic Analysis of River Systems: An Approach to Reading the Landscape” outlines the contextual principles and theories with which to ground these analyses, and takes practitioners through how to undertake such analyses.