Research In Fluvial Geomorphology Research Articles

Twenty-five years of hydromorphological restoration in the high-energy, gravel-bed rivers of southern France: What are the current benefits for bedload dynamics and sediment balance in the left-bank tributaries of the Aude River within the Minervois region?

The article synthesizes 25 years of hydromorphological restoration in the high-energy, gravel-bed rivers of southern France. In the Minervois region, the authors highlight the challenges and advancements made in riverbed restoration following the catastrophic flood of November 1999. This event catalyzed research in fluvial geomorphology and led to significant restoration initiatives implemented by the SMMAR. The article pays particular attention to the role of floods and ordinary flow events in the hydromorphological functioning of the channels, specifically focusing on hydraulic geometry, channel pattern, bedload transport, and sediment balance. The methods developed rely on field observations and measurements, as well as image processing. Between 2012 and 2024, the transport distances of cobbles were monitored in the watersheds using RFID technology (passive and active microchips). From 2016 to 2021, sediment balances of the restored river sections were quantified through LiDAR surveys to better understand how rivers respond to the new flow conditions and channel morphology resulting from restoration efforts. The results indicate that the restored sections function as preferential sediment storage areas. Although the restoration has improved sediment transport conditions during floods, several tributaries do not contribute sufficiently to the sediment recharge of the main channels, leading to chronic sediment deficits. The data also emphasize the importance of ordinary flows in sediment transport, which can often result in riverbed incision. To achieve a more balanced sediment supply, the authors advocate for the reactivation of sediment sources at the watershed scale.

Tidal impacts on downstream hydraulic geometry of a tide-influenced delta

Variations in river hydraulic geometry (HG) are of fundamental importance to fluvial geomorphological research and catchment management. In tide-influenced river deltas, channel geometry displays a mixed scaling behavior since the channel forming discharge is of both tidal and river origins. This study aims to map the tidal signature on delta morphology in the Pearl River Delta (PRD) channel network. The model results of a 2D numerical model are used to analyze the spatial variations of river and tidal discharges and their relations with representative channel geometry throughout the delta. Downstream HG of the distributary channels in the PRD features distinct characteristics in three zones. The transition points in morphology, which splits the delta into river- and tide-dominated parts, coincide with those in the mean flow velocity, the ratio of maximum tidal discharge amplitude (MTDA) to fluvial discharge. The ratio of MTDA to river discharge scales with bifurcation order. The water level setup created by non-linear tidal and fluvial interactions affects the discharge division at tidal bifurcations. In general, the net tidal impact is to attenuate the inequality in discharge division in the PRD. The tide is non-negligible in the cross-sectional morphology and plays a decisive role in the formation of the river channel in the seaward portion of the delta.

LEARNING, DOING AND PROFESSIONAL DEVELOPMENT – THE RIVER STYLES FRAMEWORK AS A TOOL TO SUPPORT THE DEVELOPMENT OF COHERENT AND STRATEGIC APPROACHES FOR LAND AND WATER MANAGEMENT IN BRAZIL

Ongoing development, training and adaptive learning are fundamental to professional practice in river science and management. River Styles Framework provides a coherent, carefully structured (scaffolded) approach that synthesises geomorphic understandings of rivers as a baseline to support river management applications. As the approach is generic, principles and procedures can applied in any setting. The Framework and its applications build on fundamental research into river forms and processes. Importantly, the Framework was developed in collaboration with river management agencies in New South Wales, Australia and has been used in collaboration with practitioners elsewhere in the world. This paper documents the process used to teach the five-day River Styles professional short course in Brazil, September 2017. We report upon some pedagogical foundations of the Framework to explain the approach to teaching. We present an overview of the types of exercises taught in Brazil, showing how local fieldwork and case studies support the uptake of this geomorphic information to inform river management. We emphasise the importance of careful planning in delivering a coherent product that integrates remotely-sensed work, field interpretation skills and lecture/practical class exercises. These exercises build upon foundation research in fluvial geomorphology in the Macaé Catchment in Rio de Janeiro State.

Arctic Mackenzie Deltachannel planform evolution during 1983–2013 utilisingLandsatdata and hydrological time series

AbstractArctic deltas, such as the Mackenzie Delta, are expected to face major climate change and increased human influence in the near future. Deltas are characterised by highly dynamic fluvial processes, and changing climate will cause considerable evolution of the riverine environment. The changes are difficult to predict with existing knowledge and data. This study quantified channel planform change of the Mackenzie Delta (1983–2013), analysing its temporal and spatial patterns. We addressed the main obstacle of research on large remote areas, the lack of data, by developing a unique work flow that utilised Landsat satellite imagery, hydrological time series, remote sensing‐based change analysis, and automatic vectorisation of channels. Our results indicate that the Mackenzie Delta experienced constant evolution but at a highly varying rate over the 30 years. The study demonstrates that the magnitude and duration of flood peaks and the presence of spring ice breakup floods determine the rate of Arctic delta planform change. Changing winter conditions and spring flood magnitudes may therefore affect the stability of Arctic deltas. However, no clear trends towards decreased recurrence or magnitude of spring floods or increased instability of the delta plain have yet been observed in the Mackenzie Delta. The delta plain was most dynamic at the beginning and at the end of the examined period, corresponding to intense flooding, whereas the rates of change were subtle during the low‐flood period 1994–2007. The largest changes have occurred along the wide Middle Channel and in the outermost delta. Relative to their size, however, smaller meandering channels have been highly dynamic. Hotspots of change in the delta plain are located in anastomosing and braiding channel segments and, at the local scale, in point bars and cut‐banks along meandering channels. Our study describes how Landsat satellite data can be utilised for advancing fluvial geomorphological research in remote areas. However, cloudiness in the delta restricts production of dense time series with simultaneous coverage of the whole area and requires manual preprocessing.

Detailed fluvial-geomorphologic mapping of wadeable streams: a proposal of universal map symbology

ABSTRACTDetailed maps are important components of fluvial-geomorphological research, connecting several tools, namely field mapping of presented channel and floodplain forms and the assessment of fluvial processes and hydromorphological conditions of current river management. In this paper, we propose a universal map legend for the complex mapping of small stream channels in a detailed scale, which means including both the channel and adjacent floodplain segments. With the help of the symbology we are able to demonstrate both fluvial forms (i.e. individual features, grain size of bed sediments and fluvial deposits) and fluvial processes (i.e. contemporary trends in channels, character of lateral sediment inputs and flow characteristics) in a single map. In total, nearly 150 symbols were proposed and created as a combination of TrueType font and ArcGIS Style files. However, the principle can be used in various software. The work is accompanied by three map examples from the Nízký Jeseník Mts (the Stará Voda Stream) and the Moravskoslezské Beskydy Mts (the Lubina and Bystrý Streams).

New opportunities for experiments in fluvial geomorphology: the flume PTETHYS

In recent decades both physical modelling and computer simulation of fluvial processes has undergone rapid progress. The paper summarizes the achievements of both international and Hungarian laboratory experiments in fluvial geomorphology. Then the new automatically governed flume facility, called PTETHYS (Project for Tectonical and Hydrological Simulations) recently set up at the Faculty of Natural Sciences, University of Pécs, is presented and some of the new opportunities it offers for research in fluvial geomorphology are briefly demonstrated: the identification of geomorphological thresholds; modelling the generation of (flash) floods and its application for the reconstruction of the architectural elements and geomorphic evolution of floodplains. Some important channel parameters can be quantitatively investigated: channel cross-section change, amount of bedload influencing braiding, current velocity distribution etc. The novelty of the facility is the easy adjustment of channel slope and continuous experimenting (no need for interruption as in the case of laserscanned experiments). The scaling necessary for quantitative analyses is also tackled.

Application of Basin Morphometry Laws in catchments of the south-western quadrangle of south-eastern Nigeria

The relationship between process and form has been at the core of research in fluvial geomorphology. Form-process relationships of a natural river basin are strongly influenced by its hydrologic and sedimentologic processes as basin morphometric properties of length, shape, and relief, change in response to various hydrologic stimuli from the environment, but usually in line with well established laws. In the four river basins (Orashi, Otamiri, Sombreiro, New Calabar) examined in this study, however, empirical evidence does not conform neatly with theoretical postulates. Remarkable variations are noted in the morphometric properties of the catchments, when compared with established morphometric laws. The most varied in conformity are the Orashi and New Calabar basins, although the Sombreiro and Otamiri catchments also show some level of variation. Prime explanation for the morphometric and topographic non-conformity is caused by the nature of surficial material and the profoundly shallow relief of much of the study area, especially the alluvial flood and deltaic plains to the south and south-west of the study area.

Review of research in fluvial geomorphology 2010–2011

This progress report on the discipline of fluvial geomorphology for the calendar years 2010–2011 extends the analysis carried out by Stott (2010, 2011) of papers published in Earth Surface Processes and Landforms ( ESPL) during the calendar years 2006–2007 and 2008–2009 to include the period of 2010–2011. A total of 327 papers were published in the 30 issues of ESPL during the review period, up from 284 during 2006–2007 and 300 in 2008–2009. Of these papers, 175 (54%) were within the subject area of fluvial geomorphology, compared to 125 out of 284 (44%) in the 2006–2007 period, and 113 out of 297 (38%) in the 2008–2009 period. In comparing the three two-year periods covering 2006–2011, the numbers of papers in each of 10 subdisciplines within fluvial geomorphology (e.g. bank erosion, hydraulics, soil erosion) changed markedly. For example, river management, restoration and the effects of vegetation on fluvial systems changed from first in rank in 2006–2007 to tied in fourth place in 2008–2009 and eighth in 2010–2011. In contrast, the subdiscipline of soil erosion was consistently the second-ranked topic in each of the three two-year periods. Following the analysis of patterns of publications in ESPL, selected papers from each of the 10 subdisciplines are reviewed. The articles discussed were selected by searching using keywords from the 10 subdisciplines using http://scholar.google.co.uk, then selecting a relevant journal article from the first 10 hits returned. In this way, 33 papers drawn from 22 journals were sampled and their key findings are summarized.

Spatial relationships in a dendritic network: the herpetofaunal metacommunity of the Mattole River catchment of northwest California

We investigated the aquatic and riparian herpetofauna in a 789 km 2 river catchment in northwest California to examine competing theories of biotic community structuring in catchment stream networks. Research in fluvial geomorphology has resulted in multi-scale models of dynamic processes that cyclically create, maintain, and destroy environments in stream networks of mountain catchments. These models have been applied to understanding distributions of invertebrates, algae, fishes and their habitats across entire basin networks, but similar approaches with herpetofauna are rare. We examined multi-scale spatial patterns of multiple species as they related to variation in channel types, channel settings, and within-channel attributes that result from these processes. From 83 reaches distributed randomly throughout the watershed, we distinguished four channel types: 1) high gradient with cascade structure; 2) 2� 4% gradient with steppool structure controlled by moderately steep valleys; 3) slightly entrenched, lower gradient, plane-bed structure; and 4) low gradient, shallow, unconfined, multiple or migrating pool/riffle channels in broad alluvial valleys. The composition of herpetofauna differed in five of six pair-wise comparisons among these channel types, indicating a minimum of three distinct mesoscale assemblages. We used non-parametric multiple regression (NPMR) to examine relationships at multiple spatial scales. NPMR revealed species-specific associations with channel settings and within-channel environments among species sharing the same sets of channel types. Morphological adaptations, biophysical limits and natural histories of each species best explained their associations with distinct sets of attributes surrounding and within channel types. While each set of species has similarly adapted to fluvial and geomorphic disturbance processes structuring channels at the mesoscale, species within each set have adapted to a unique set of attributes that are best discerned when their spatial relationships are examined across multiple spatial scales. We evaluated the various spatial patterns against hypotheses of stream community organization and metacommunity perspectives.

Patterns of anabranching channels: The ultimate end-member adjustment of mega rivers

Large fluvial systems adjust to a combination of controls to form distinctive channels, which represent a dominant factor in the evolution of floodplain geomorphology and sedimentology. Fluvial geomorphology has commonly classified river channels into meandering, straight and braiding patterns, which are seen to represent a continuum of channel geometry. Anabranching patterns, rivers with multiple channels, however, are characteristic of many rivers. The identification of a combination of variables that discriminates specific channel patterns has been a significant focus of research in fluvial geomorphology. The development of this body of knowledge, however, has been established from medium and small rivers, and laboratory flume studies. Very few of these research ideas developed from analysis of large fluvial systems. This paper assesses the pattern of channel adjustment of large fluvial systems by employing hydraulic geometry, discharge, w/ d, slope, grain size, stream power, specific stream power, and Froude number ( Q mean > 1000 m 3/s). The study demonstrates that methods currently used to discriminate channel patterns are not useful when applied to very large rivers. Further, with the exception of the Lower Mississippi, alluvial rivers with mean annual discharges greater than ~ 17,000 m 3/s, here classified as mega rivers, do not generate single thread meandering or typical braided patterns. These mega rivers develop anabranching patterns.

Nikolay I. Makkaveev and the development of Fluvial Geomorphology in Russia and the former Soviet Union

Abstract 2008 marks the centenary of the birth of Professor Nikolay Ivanovich Makkaveev (1908–1983), a former Professor in the Faculty of Geography at Moscow State University and the founder of the Laboratory of Soil Erosion and Fluvial Processes in the Faculty of Geography. Professor Makkaveev is little known in the west, but he must be seen as a highly influential and important figure in the development of fluvial geomorphology in Russia and the former Soviet Union. He was responsible for drawing together the nascent work on fluvial geomorphology in Russia, which was founded in the different fields of soil science and soil conservation and waterway engineering, and his monograph entitled ‘The river channel and erosion in its basin’ published in 1955 emphasised the need for a holistic treatment of the river and its drainage basin. In advocating a holistic systems approach, Makkaveev's ideas paralleled similar developments in the west and anticipated future recognition of the importance of an understanding of the geomorphological functioning of drainage basins for effective catchment and river basin management. Makkaveev's ideas were highly influential in the development of research in fluvial geomorphology in Russia and the former Soviet Union and the Laboratory of Soil Erosion and Fluvial Processes that he founded within Moscow State University remains a highly successful and influential focus of fluvial geomorphological research in Russia.

Variability and uncertainty in reach bankfull hydraulic geometry

Observations of the hydraulic geometry of river channels are widely used in fluvial geomorphological research and river management. Variations in hydraulic geometry observed at sites through a region or through time are often assumed to be true variation, but measurement uncertainty will also contribute to these variations. Few studies have quantified the effect of error. This paper evaluates uncertainty in bankfull hydraulic geometry for 114 river sites in southeast Australia. These sites represent a broad range of river types, including lowland and upland rivers in temperate and semi-arid climates. Results will be applicable to hydraulic geometry investigations worldwide when consistent channel survey techniques are used. Uncertainty is quantified relative to observed variation in hydraulic geometry between sites. For bankfull discharge, width, depth, velocity and slope, respectively 4%, 3%, 7%, 23% and 42% of the site-to-site variation can be attributed to uncertainty. Uncertainty in the variability of bankfull metrics for each of the 114 sites (e.g. standard deviation in bankfull width) is higher, contributing between 40% and 50% of the observed between site variation. Mean width and depth are more sensitive to sample errors associated with cross-section surveys. Bankfull discharge, velocity and slope are more sensitive to errors in parameters for the gradually-varied flow model required to model flow conditions at bankfull discharge. We develop models to predict the error resulting from using hydraulic models to predict bankfull flow, which may be used to estimate the appropriate number and spacing of cross-section surveys required for accurate modelling. These models relate error in bankfull metrics to channel attributes and the number and spacing of cross-sections. To minimise errors, sites must be longer in low gradient channels and have more cross-sections in more variable channels.

Toward a theory for step pools in stream channels

Over the past 10 to 15 years there has been a surge in interest in step-pool streams in fluvial geomorphological research. This reflects recognition of the geomorphic significance of step pools in high-gradient channels, and a growing interest in rivers in mountainous regions in general. This paper synthesizes the recent literature on step pools, with particular reference to theory construction and progress made over the past decade and a half. Four groups of contributions are identified. The first focuses on understanding morphological relations in order to seek causal mechanisms. The second emphasizes processes that result from the step-pool configuration. The third is a group of integrative studies that seek broader explanations for step-pool sequences. The fourth and growing body of literature applies what has been learned about step pools toward managing and restoring steep channels. We conclude by highlighting some future possible research directions toward gaining a complete explanation for step pools in stream channels.

A multiscale conceptual framework for integrated ecogeomorphological research to support stream naturalization in the agricultural Midwest.

The complexity of fluvial systems necessitates interdisciplinary research in fluvial geomorphology and aquatic ecology to develop a fundamental understanding of interconnections among biotic and abiotic aspects of these systems. Integrated knowledge of this type is vital for environmental management of streams in human-dominated environments. A conceptual framework is presented for integrating geomorphological and ecological research on streams in East Central Illinois, USA, a glaciated low-relief agricultural landscape. The framework embodies a multiscale perspective in which a geomorphological conception of the fluvial system is used to define a hierarchy of characteristic spatial scales for exploring important linkages between stream geomorphology and aquatic ecology. The focus ecologically is on fish, because a rich body of historical information exists on fisheries in East Central Illinois and because past work has suggested that availability of physical habitat is a major factor influencing the community characteristics of fish in this human-altered environment. The hierarchy embodied in the framework includes the network, link, planform, bar unit, bar element, and bedform/grain scales. Background knowledge from past research is drawn upon to identify potential linkages between geomorphological and ecological conditions at each of these scales. The conceptual framework is useful for guiding integrated ecogeomorphological research at specific scales and across different scales. It also is helpful for illustrating how widespread human modification of streams has catastrophically altered the scalar structure of fluvial systems in East Central Illinois. Knowledge emerging from the integrated research provides a basis for environmental-management schemes directed toward stream naturalization.

Monitoring and modelling morphological change in a braided gravel-bed river using high resolution GPS-based survey

Recent research in fluvial geomorphology has emphasized the direct monitoring of channel topography as a useful tool to better understand the interrelationship between river form and process, and in particular to estimate bedload transport rates and reach-scale sediment budgets. Until recently, however, this morphometric approach has been limited to comparison of repeatedly surveyed cross-sections with the associated problems of low frequency sampling and an emphasis on cross-stream as opposed to downstream morphological dynamics. Recent advances in analytical photogrammetry have, however, permitted the acquisition of data at sufficient resolutions to represent macroform (101 m) and microform (10° m) channel geometry, in fully three dimensions. While inherently spatially distributed, the photogrammetric approach to land-surveying is, however, restricted to observable areas of the channel and is thus of limited use in the subaqueous zone, especially if flows are turbid or highly coloured. This paper presents an alternative approach to the study of three-dimensional morphological dynamics of a divided reach of the gravelly River Feshie, Scotland, in which topographic survey of both exposed and submerged areas of the reach was undertaken using the Global Positioning System (GPS). Survey results from two field programmes in 1998 and 1999 are presented in which a Geotronics Geotracer 2000, real-time kinematic GPS receiving unit was used to survey a 200 × 80 m reach. Rapid radial survey methods were employed permitting the collection of 2000 + survey points per day, giving a mean density over the 13 ha reach of 1·1 points per square metre. A detailed assessment of survey errors and DEM quality is presented and a limit of detection of c. 10 cm proposed as an upper threshold for the identification of significant change between DEMs. Preliminary interpretation of channel dynamics in 1998–99 reveals relatively little change to the overall macroscale reach structure. DEM differencing techniques, however, highlight important local changes including the progradation of submerged bar fronts, bar head aggradation and scour along major channel thalwegs and the erosion of fines from sloughs. Copyright © 2000 John Wiley & Sons, Ltd.

System design for catchment-scale approaches to studying river channel adjustments using a GIS

In comparison to studies in hydrology, progress in developing Geographical Information Systems (GISs) for catchment-based research in fluvial geomorphology appears to be slow due to problems relating to the digital representation of the channel perimeter, the non-incremental basis of river channel change and the extended timescales over which geomorphological change occurs. Acknowledging these constraints, critical system and parameter requirements are defined from which a GIS is implemented combining Laser-Scan mapping capabilities and macros with 'C' programs and ARC/INFO routines. Accurate data representation of linear and areal features is critical for deriving terrain and flow properties and an 'error' checking method for calculating upstream catchment areas is described. In general, system requirements are met with minimum data compromise but at cost to the system complexity and 'user-friendliness'. The potential for obtaining novel insights exists but requires careful attention to data quality standards.

Developments in monitoring and modelling small‐scale river bed topography

AbstractRecent research in fluvial geomorphology has emphasized the spatially distributed feedbacks amongst river channel topography, flow hydraulics and sediment transport. Although understanding of the behaviour of dynamic river channels has been increased markedly through detailed within‐channel process studies, less attention has been given to the accurate monitoring and terrain modelling of river channel form using three‐dimensional measurements. However, such information is useful in two distinct senses. Firstly, it is one of the necessary boundary conditions for a physically based, deterministic modelling approach in which three‐dimensional topography and river discharge drive within‐channel flow hydraulics and ultimately spatial patterns of erosion and deposition and therefore channel change. Secondly, research has shown that an alternative means of estimating the medium‐term bedload transport rate can be based upon monitoring spatial patterns of erosion and deposition within the river channel. This paper presents a detailed assessment of the distributed monitoring and terrain modelling of river bed topography using a technique that combines rigorous analytical photogrammetry with rapid ground survey. The availability of increasingly sophisticated terrain modelling packages developed for civil engineering application allows the representation of topographic information as a landform surface. Intercomparison of landform surfaces allows visualization and quantification of spatial patterns of erosion and deposition. A detailed assessment is undertaken of the quality of the morphological information acquired. This allow some general comments to be made concerning the use of more traditional methods to monitor and represent small‐scale river channel morphology.

INTERREGIONAL COMPARISON OF ALLUVIAL STREAM CHANNEL MORPHOLOGY: GREAT PLAINS VERSUS CENTRAL LOWLANDS1

ABSTRACT: Stream channel development is a complicated process involving many factors. A major goal of research in fluvial geomorphology is to develop an understanding of the relations between channel form, water discharge, and sediment discharge characteristics. The concept of thresholds has been introduced as an element in fluvial processes, with the implication that the factors involved in a process might change in some way as threshold boundaries are passed. This study is focused on the extent to which a particular regional boundary represents a threshold in the process of stream channel development. Twenty‐four alluvial stream channels from the Great Plains region and 24 from the Central Lowlands region are compared with regard to the distributional form, central tendency and dispersion characteristics, and correlation structure of ten variables, including indicators of discharge, channel sediment, and channel morphology. The results suggest that these aspects of the data are very similar between the regions, except for certain differences in central tendency characteristics, which are assumed to reflect underlying differences between the regions in geology and climate. In general, the results support the idea that this regional boundary is not an effective threshold with respect to the stream channel development process, and that, therefore, stream channels develop in these environmentally distinct regions by way of a similar process.

Causal and functional relations in fluvial geomorphology

AbstractThe concept of causality has been a fundamental principle of scientific investigation for many centuries. Recently, however, there has been a significant reappraisal of the philosophical basis of the concept of causality and this has important implications for future geomorphological research.It is now recognized that there are two approaches to the study of relations between variables. Conventionally knowledge was divided into classes and, on the basis of time precedence, causal relations were defined. While this approach enables static systems to be analysed it does not apply to dynamic systems which exhibit mutual causality. This traditional view of knowledge became obsolete with the introduction of the concept of the continuum. Algebraic techniques now enable the solution of systems of simultaneous equations, provided that there are as many equations as unknowns. Significantly this approach applies to dynamic as well as static systems.Further advances in fluvial geomorphological research are dependent on the adoption of mathematical reasoning. This will concentrate research on the mode and rate of operation of channel processes and feedback mechanisms. Given this information it will be possible to develop a static process‐response model to explain and predict channel response to a set of input conditions, and a dynamic model to simulate channel development through time and space.