Kenneth Gregory
University of Southampton
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Applied Geography | 1992
Kenneth Gregory; R.J. Davis; P.W. Downs
Abstract Techniques for determining the precise location of river channel changes are required to complement space-time substitution and three major techniques are illustrated for the Monks Brook drainage basin in central southern England. First, channel widths were measured from large-scale topographic maps of three dates, the results compared with field measurements, and the spatial pattern of planform change was constructed. Secondly, field indicators based on vegetation, structures and morphological criteria were used to quantify channel width, depth and capacity changes at particular locations. Thirdly, mapping of the spatial variation in channel adjustments using field indicators was shown to be viable by comparing the results obtained by two independent operators surveying the same reach. Channel change due to the influence of urbanization on the Monks Brook involves capacity increases of up to 2–2.5 times, width increases of up to 2.2 times and bed lowering of up to 0.4 m. The three groups of techniques are capable of being applied to other channels. Channel capacity enlargements are demonstrated to be spatially discontinuous and may involve widening, deepening, or a combination of the two. The character and location of such changes can be an important consideration for channel management.
Annals of The Association of American Geographers | 2001
Anne Chin; Kenneth Gregory
Comparatively few studies of stream channel adjustment following urbanization have been undertaken in dryland environments. In the new master planned community of Fountain Hills, a residential area near Phoenix, Arizona developed since the 1970s, surveys in 1987 and 2001 of ephemeral wash channels show that they are larger than comparable channels in humid areas, reflecting the effects of rare but substantial floods. Morphological adjustment is spatially varied and is influenced by wide road crossings that are responsible for fragmentation of the adjusting channels into segments. By 2001, these segments are characterized by scour immediately downstream of a crossing and a relatively high width-depth ratio farther downstream before the next road crossing. Such spatially distributed responses have caused management problems unique to arid environments, so that, although road drainage was originally allowed to flow into the washes at the crossings, the stormwater network has now been augmented to improve drainage and to inhibit scour at the crossings. In maintaining such washes, consideration of channel adjustments as a result of urbanization could form the basis for an approach comparable to restoration methods in more humid areas.
Environmental Management | 1991
Peter W. Downs; Kenneth Gregory; Andrew Brookes
Land and water management is increasingly focused upon the drainage basin. Thirty-six terms recently used for schemes of “integrated basin management” include reference to the subject or area and to the aims of integrated river basin management, often without allusion to the multiobjective nature. Diversity in usage of terms has occurred because of the involvement of different disciplines, of the increasing coherence of the drainage basin approach, and the problems posed in particular parts of the world. The components included in 21 different approaches are analyzed, and, in addition to showing that components related broadly to water supply, river channel, land, and leisure aspects, it is concluded that there are essentially five interrelated facets of integrated basin management that involved water, channel, land, ecology, and human activity. Two aspects not fully included in many previous schemes concern river channel changes and the dynamic integrity of the fluvial system. To clarify the terminology used, it is suggested that the termcomprehensive river basin management should be used where a wide range of components is involved, whereasintegrated basin management can signify the interactions of components and the dominance of certain components in the particular area.Holistic river basin management is advocated as a term representing an approach that is both fully comprehensive and integrated but also embraces the energetics of the river system and consideration of changes of river channels and of human impacts throughout the river system. The paradigm of working with the river can be extended to one of working with the river in the holistic basin context.
Geomorphology | 1993
Kenneth Gregory; R.J. Davis; Stephen Tooth
Abstract Debris dams of coarse woody debris have a significant influence on channel processes in forested areas but few detailed studies have been made of variations within a single basin. Results from previous research are standardised and show that average variations throughout basins include densities of debris dams up to 40 per 100 metres of channel and can involve a loading value of up to 225 kg per m2 of channel. Variations have been ascribed to distance downstream, to channel width, to land-use effects, to felling, and to the management of coarse woody debris in streams. This study of the Lymington Basin, 110.4 km2 in drainage area, shows that the input of storm debris resulting from blowdown accounts for 45% of the gross load. The remaining 55% net load varies to distance downstream, to land use with the greatest loads in deciduous woodland areas, and according to management removal of debris from streams and multiple regression equations are provided. It is deduced that as a consequence of long-term management the present channel debris may be as little as 7% of the total net load that could have been present if no management had occurred.
Environmental Management | 2008
Anne Chin; Melinda D. Daniels; Michael A. Urban; Hervé Piégay; Kenneth Gregory; Wendy Bigler; A. Butt; Judith L. Grable; Stanley V. Gregory; Martin Lafrenz; Laura R. Laurencio; Ellen Wohl
This article reports a study of the public perception of large wood in rivers and streams in the United States. Large wood is an element of freshwater aquatic ecosystems that has attracted much scientific interest in recent years because of its value in biological and geomorphological processes. At the heart of the issue is the nature of the relationship between scientific recognition of the ecological and geomorphological benefits of wood in rivers, management practices utilizing wood for river remediation progress, and public perceptions of in-channel wood. Surveys of students’ perceptions of riverscapes with and without large wood in the states of Colorado, Connecticut, Georgia, Illinois, Iowa, Missouri, Oregon, and Texas suggest that many individuals in the United States adhere to traditionally negative views of wood. Except for students in Oregon, most respondents considered photographs of riverscapes with wood to be less aesthetically pleasing and needing more improvement than rivers without wood. Analysis of reasons given for improvement needs suggest that Oregon students are concerned with improving channels without wood for fauna habitat, whereas respondents elsewhere focused on the need for cleaning wood-rich channels for flood risk management. These results underscore the importance of public education to increase awareness of the geomorphological and ecological significance of wood in stream systems. This awareness should foster more positive attitudes toward wood. An integrated program of research, education, and policy is advocated to bridge the gap between scientific knowledge and public perception for effective management and restoration of river systems with wood.
Area | 2002
Kenneth Gregory; Anne Chin
In managing urban stream channels there are pressures to use soft engineering techniques to restore channels wherever possible, to undertake management within a drainage basin context, to produce sustainable solutions and to consider community views. However, specific methods for characterizing the channel network in terms of possible management options have not been developed explicitly for urban areas. A method of characterizing the entire drainage network of urban areas, based upon segmentation of the stream channel network according to the incidence of road crossings and stormwater outfalls, is proposed together with consideration of ways in which the segments can be characterized, including stream channel hazards as a means of providing one basis for urban channel management.
Journal of Hydrology | 1989
Geraldene Wharton; N.W. Arnell; Kenneth Gregory; Angela M. Gurnell
Abstract Estimates of flood discharges are often required at ungauged sites. A considerable amount of research has been devoted to the production of reliable flood estimates for ungauged catchments but such estimates are costly to obtain. Although a catchment-based approach has often been used, for example in the U.K. Flood Studies Report, an alternative method is to estimate flows at ungauged sites from river channel dimensions. Data for 72 rivers throughout the U.K. are employed to establish regression relations between measures of peak discharge ( Q 5 , mean annual flood, and Q 5 and Q 1.5 are the floods with return periods of 5 and 1.5 years respectively) and channel dimensions (cross sectional area, width and depth at bankfull stage). Channel measurements of area, width and depth individually account for up to 85% of the variation of the three discharge variables and the explanation is greatly superior to that obtained by using the more frequently used drainage basin area variable for the same data set. Relationships between discharge and channel dimensions give a rapif means of flow estimation from channel dimensions and can be used effectively prior to hydrological or hydraulic methods.
The Geographical Journal | 1984
M. G. Anderson; Kenneth Gregory
Shows the range of subdisciplines and approaches that contribute to palaeohydrology. Includes reviews and examples of specific approaches, including gully development, drainage network development, vegetation changes, and river channel planform changes. Concentrates on middle and high latitudes.
The Geographical Journal | 1988
A. S. Goudie; Kenneth Gregory; D. E. Walling
During the last twenty years, more attention has steadily been devoted to the significance of human activity upon the environment. This book identifies ways in which human activity has affected environmental processes. Each chapter examines a particular aspect of environmental processes showing how they have been affected and then gives a brief indication of the significance for the management of the environment. The chapters are organized by the major spheres which make up the Earths environment under the headings atmosphere, hydrosphere, geosphere, pedosphere and biosphere. The introductory chapter looks at the way in which investigations have been carried out and the concluding chapter relates such investigations to management at both the national and international level.
Archive | 2014
Kenneth Gregory; John Lewin
Gregory, K. J., Lewin, J. (2014). The Basics of Geomorphology: Key Concepts. Sage Publications.