BOOK REVIEWS 303

Although it is recognized that erosion surveys need to be linked to measurements of soil erosion in the field, these have only just begun. An indication of long term erosion rates is obtained from the studies of valley infils by J. L. Monnon. Presentday erosion is being investi- gated on erosion plots and T. Messer provides data for 22 storms in 1977 for five plots: two where tillage is used, two where chemical weeding but no tillage occurs, and one under grass. Where there are two plots for a particular condition, however, they are not replicas but are, instead, of different lengths, 20 m and 40 m. The reason for this is not clear and no comment is made on effects of plot size on this type of experiment even though the data show that soil loss per unit area is greater on the smaller plots. Correlations of the soil loss data with various expressions of rainfall erosivity show that Lal’s AI,,, is the best index. It is surprising, there- fore, that this index is not included in another paper by T. Messer on the regional variations in erosivity in Alsace. Here only Fournier’s p 2 / P and the lesser known index of Deffontaines, based on daily rainfall totals, are used and no evidence is presented to show that either of these indices actually correlates with soil loss.

T. Saba El-Ghossain and J. Schwing examine the erodibility of the soils and both conclude that the HCnin structural stability index is not applicable to the very sandy or the very clayey soils of the vineyards. Better measures of erodibility are the silt/clay ratio and the

index of Dumas. J. Schwing also reports on two studies which, although marginal to the main research pro- gramme, are of interest in comparison with investiga- tions elsewhere. The work on the effects of burrowing animals of soil detachment parallels that carried out in Luxemburg by A. C. Imeson and his colleagues from Amsterdam whilst the study of the use of copper as a tracer element supports similar work in German vine- yards by U. Schwertmann.

Of less value are the two papers which conclude the volume but are totally unrelated to it. One describes the rainfall simulator designed in Hungary by B. Kazo but only to emphasize its limitations in terms of poor control over intensity and its coverage of too small a plot size. The other summarizes the research on soil erosion being carried out in Hungary.

My main criticism of the material presented in this volume is that it contributes almost nothing to what should be a major objective of soil erosion research which is how to reduce erosion to an acceptable level. Erosion control is simply not mentioned. Without this background it is difficult to determine the real purpose of the investigations carried out so far.

R. P. C. MORGAN National College of Agricultural Engineering,

Silsoe, Bedford

FLOODS-A GEOGRAPHICAL PERSPECTIVE, R. c. Ward, The Macmillan Press, London, 1978. No. of pages: 244. Price: f3.95.

Concern over both natural and man-made environ- mental hazards has seldom been higher than it is today and of all these hazards few are more international than that of flooding. It was with interest then, that the reviewer received this text which offered a geographical perspective on the flood problem. It proved to have the same qualities as earlier textbooks written by the same author-an easy, readable style, ample illustration and a sound, fairly comprehensive review basis.

Although there is no explicit broad subdivision of the book, it is possible to identify three major themes that occupy the bulk of the twelve chapters which comprise this book. In Chapters two to four the author examines the causes of flooding: Chapter two, rainfall floods; Chapter three, floods having a significant snow or ice melt component; Chapter four the ‘sweeper’ chapter dealing mainly with sea floods, but also covering such areas as dam failure and landslips into impoundments.

In the second section, Chapters six and seven, Ward

discusses the problems of flood prediction (for design purposes) and flood forecasting (for warning purposes). These are somewhat technical chapters and suffer from the obvious difficulty for any author-that of discussing prediction and forecasting for so many different flood causes in the forty-four pages available. One senses that this problem reaches a climax as the author selects from and compresses Chow’s 107 ‘in use’ flood prediction formulae, the several volumes of NERC flood report and many other relevant texts in the flood prediction chapter. None the less this remains one of the best sections of the text.

The third section, Chapters eight to eleven, deals with the control of flooding. In the first of these chapters Ward examines possible adjustments to flood hazard. Here the author appears to have followed closely upon the work of White and his colleagues and students at the Chicago School in the sixties. Chapter nine reviews the role of the catchment in the abatement and exacerbation of flooding, whilst in Chapter ten the civil engineering responses to flooding are assessed. These three chapters represent the familiar breakdown into floodplain. catchment and channel control. The last chapter in this

3 04 BOOK REVIEWS

section, the penultimate in the book, looks at a variety of economic influences on, and responses to, the flood hazard.

This is not a text without faults, however. Chapters eight to eleven are very uncritical. One doubts the value of a number of the generalizations made, especially in relation to the role of catchment land use. The work of the Chicago school is becoming rather dated and in any case is probably best read directly as it is too extensive to paraphrase successfully. In Chapter eleven the dis- cussion of cost benefit analysis is extremely thin. Time and discount rate problems are not covered, benefit risk analysis is not explored, but of more significance is the fact that for the first time in the book a number of important references (to cost benefit review and dis- cussion papers that might have alleviated the inadequacies outlined above) are missing. In addition this chapter contains a section on systems analysis in which the author implies that this is an alternative to cost benefit analysis. This is clearly very doubtful ground given the operational significance of systems analysis. In Chapters four and six more is needed in relation to the causes and prediction of coastal flooding. Prediction of

lowest astronomic tides, variation in spring tides and the frequency relationships demonstrated by Wemelsfelder could have been profitably covered. Finally, Chapter five, an examination of floods as geomorphic agents, seems very brief especially in a text claiming a geo- graphic perspective.

To summarize, this is an enjoyable and readable review test. It makes no original contribution to the field of study but it seems clear that this was never the author’s intention. Although it does not earn a place on the bookshelves of flood specialists it will be a very useful text at the lower to middle undergraduate level. In this respect it is rather sad that it contains no worked examples in the analytical sections to complement the case study examples of flooding that appear in other sections. At the price it seems good value for libraries and for students taking courses that have a substantial flood studies component.

ADRIAN MCDONALD School of Geography

University of Leeds

MECHANICS OF SEDIMENT TRANSPORTATION AND ALLUVIAL STREAM PROBLEMS, R. J. Garde and K. G. Ranga Raju, Halsted Press, New York (Wiley Eastern Limited, New Delhi), 1977. Price: €7.25. No. of pages: 483.

The subject of sediment transportation and stream mechanics is a vexing one because the scope of the problem is nearly beyond the capabilities of the indivi- dual worker. Books on the subject are necessarily compendia of often conflicting results of work by many researchers, and can be bewildering hodgepodges unless careful organization and critical evaluation of differing analyses have been exercised. Thus, new books on the subject by senior workers, especially foreign ones, are generally received with enthusiasm as they may present new insight into old problems and access to a different body of data and literature. This book by Drs. Garde and Ranga Raju does not warrant such enthusiasm.

The book has 16 chapters, and the subject matter is treated in two parts. The first eight chapters are intro- ductory or analytical in nature, and deal with origin and properties of sediments, incipient motion of sediment particles, regimes of flow, resistance to flow and velocity distribution in alluvial streams, bed load transport and saltation, suspended load transport, and total load transport. The second eight chapters deal with applied problems of sediment samples and sampling, design of stable channels, alluvial streams and their hydraulic geometry, stream bed variation in alluvial streams, variation in plan-form of streams, sediment control in

canals, river training and bank protection, and miscel- laneous problems of alluvial river models, mud-flows, density currents, and sediment transport through pipes. Each chapter has an extensive list of references, although post-1970 ones are sparse and many developments since 1970 are not included. Treatment of this extensive material varies from over-detailed to over-simplified and gross errors of content occur in areas outside the authors’ area of knowledge, especially in geology. For example, they state in the introduction (pp. 12-13) that deserts are ‘regions in which the average annual rainfall is less than ten inches’ and ‘surface drainages are rare and therefore stream erosion is almost absent (emphasis added)’. In the lengthy section on sediment size analysis, which is too long for its lack of detail, the authors recommend the visual accumulation tube method for size analysis of silt- and clay-size material, but it is only appropriate for sand sizes. In the analytical chapters, the authors have achieved an exhaustive compilation at the expense of comprehen- sion. The ‘critical review’ promised by the dust jacket falls short of enabling the reader to choose between different analyses for application to a given problem, and graphs of field data compared with results of different analyses are largely absent. With the exception of Chapters 12, 14 and 15 on stream bed variations, sediment control in canals, and river training and bank protection, the book generally lacks useful insight from the experience of Drs. Garde and Ranga Raju, and presents few new data for use in evaluating different analytical techniques.