Geomorphic Analysis of River Systems
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Most books on rivers deal with just that. Not surprising really and we could say the same about any other aspect of the biotic or abiotic environment. However, there is a point here. By focussing on the river, you tend not to connect it to the landscape. This is not a problem for the professional geomorphologist because they know how it fits together. It is a problem for the student or educator wanting to draw people into river studies because they need to connect theory and practice explicitly. If we add to this the need for an increasingly sophisticated response from the public to environmental issues it follows that the old way of studying might not be effective. One way that is useful is to forget the theory and tell a story. Landscapes have narratives! You can read the landscape in much the same way you can books – it’s just a question of decoding the symbols. Having used a less sophisticated version of the idea presented here to some effect with senior school students, I am drawn to the ideas presented by the authors.
How do we go about this? An opening chapter outlines the key ideas explored later on. The emphasis is on fieldwork – that geomorphology is a field science as much as a set of theories. There is the assumption that we need to understand the geomorphological processes of river formation but that we must put them in the context of the surrounding area. Above all, we must use geomorphology to help us decode the history of the area. To do this we follow a four-step process: identify individual landforms; analyse and interpret; explain the controls on the system; create a synthesis of understandings. To make any sense of this there is a need to have some basic understanding of fluvial geomorphology. Chapter two delves into this and provides as much as is needed to be able to read the landscape. It’s here that the unique nature of the book becomes apparent; most texts would continue to investigate the operations of river systems. Here, the aim is to make sure people can accurately describe and analyse the river. There will be more that needs to be done but it’s this initial picture that’s wanted.
The reader now has the basics mastered. From here, a series of chapters explore key issues, each in turn. There is a common focus: scale. The argument put forward is that processes occur at a range of scales and what is needed is to look at the process not the scale it operates at. The first chapter in this section looks at catchments and catchment sub-divisions as well as profiles, morphometrics and patterning. The next chapter deals with hydrology – the flowing of water through the river system and the operation of the hydrologic cycle. Major water movements are analysed e.g. runoff and infiltration, and their impact on channel design is noted. Now that we have a catchment of a given design and a flow of water, it’s important to see what might impede water flow. Depending on the characteristics of the catchment, there can be erosion or deposition, where the physics of water movement meets the physics of the stream bed to create the numerous dynamic patterns we see in our rivers. This in turn suggests the movement of sediment, as particles or dissolved solids. Such aspects are key features of river systems and so this chapter, one of the longer in the text, looks in some detail at a series of key theoretical and practical issues from the physics of particle movement to the description of particles sizes and depositional patterns. As well as river deposits, water action will create erosion which, depending on the initial geology of the area, will create a series of landforms. If all these elements are added up it becomes clear that we have just read through all the key processes than form rivers and river basins. What is needed is the ability to put the information together to create a narrative. We get some clue about how to do this in chapter eight which describes a classification of geomorphological units but which also has the corresponding interpretation of how that unit might have been formed. A final chapter rounds out this section. Up to this point, the focus has been the river but that is only part of the catchment – the floodplain needs a similar treatment of landscape units and interpretation.
By now, the reader has an idea of river geomorphology and some insight into the mechanics of river system structure. It’s possible to create landscape units that make geomorphological sense and plot them. The second major section of the book now focusses on the integration of all these ideas into a coherent account of river history. It’s worth remembering that this text is aimed not at geomorphology per se but a use of geomorphology in analysing landscapes. It is also aimed at highlighting some key work of the authors in their description of rivers and the use to which this information can be put. Called the ‘River Styles’ (r) framework it seeks to provide a common language to describe and analyse river systems. The first chapter focusses on river diversity. Here we can see that the various factors combine to create specific stretches of river which can then be described and analysed and their history interpreted. Some of these patterns might also give an indication of how a river might “act” under certain conditions i.e. its behaviour. Behaviour can suggest how river patterns might change under conditions of flood or drought and what the implications of this might be. Of course, rivers are not static and changes in one part obviously lead to changes in other parts – an evolution of the river landscape which again, needs to be described and interpreted. The penultimate offering in this section deals with human impact, starting with the historical impact of people. Here we see examples of human action and the resulting landforms. A final chapter analyses sediment budgets and fluxes and their impact on the river system. A very brief chapter focussing on the use of this way of working concludes the text.
If we look back over the text, a clear pattern emerges. We start by outlining the system and highlighting the main parts of fluvial geomorphology. This is then developed as a thematic, cross-scalar approach providing, for each chapter, an overview of the processes, a description of the landform units that can result and the interpretation that can be made. From this we combine all these aspects and then see how they can account for the common cross-thematic dynamics seen in actual river systems.
This is a very unusual text. It’s aim is very clearly to describe in a systematic way, the landform units of rivers. It does so by providing a theoretical background (often brief), a description of landscapes and an interpretation of the pattern analysed. The focus is on narrative – to see how a river system was formed and to be able to understand how it might develop in the future and what this means for us in terms of management. As such, the ideas here feed straight into the author’s website highlighting their method. This is practical work, fieldwork, aimed at creating readers who can read a landscape as easily as they read this well-structured text. This is vital work not just because it offers a very simple and practical entry into geomorphology but that it also allows experienced readers to analyse their own rivers and suggest management techniques and strategies for conservation. It’s a rare combination but it makes perfect sense for river management as well as education. It deserves a wide readership.
