- Email: [email protected]
An environmental appraisal of the severn barrage
The two remaining papers, by C.P.B. Hardcastle and F.H. Mann. dealt with the problems of offshore industrial development. The first took a wide view of the legal. political and economic inhibitions on the exploitation of the EEZ by UK industry. pointing out the necessity for giving sufficient legal security and physical protection to encourage the large-scale long-term investment necessarv _ for the development of offshore resources. The second described the structure and organization of tt1e oil industries operating on the UK shelf.
Preoccupations Both in the papers and in the following days of discussion. in multidisciplinary working groups and in plenary sessions. Certain preoccupa&ions were evident. The present division of responsibilities in the UK for activities in and concerning the offshore zone between about 20 government felt to departments was widely necessitate the creation of a permanent within coordinating agency the government. Such an agency could not only reconcile the sometimes conflicting interests of departments in the use of the zone (for example, where dredging and fishing compete) but could also begin to streamline the system of administration of the offshore zone so as to minimize the number of departments with which intending developers of the zone would have to deal. The necessity for a coordinating agency arises from the unsuitability of the existing categories of activity and divisions of responsibility for planning
two
development of the seas. This necessity was also reflected in the general recognition that the policing of fisheries and oil rigs could not be seen as entirely military tasks forming part of the duties of the Royal Navy. It was thought better that the funding and organization of such policing duties should reflect the wide range of interests served by them. Similar views were expressed relation in the to Hydrographcr of the Navy. whose vital role in all offshore activities sometimes seems to be inadequately acknowledged. The present state of marine research in the UK caused some disquiet. The need to develop new techniques and technology for the exploitation of areas hitherto untouched, and for the better management of existing activities. is apparent. White there is much advanced work being done. many participants felt that closer liaison between public and private sector research. and between different establishments within sectors, would minimize duplication of effort and facilitate systematic examination of the many problems which remain to be solved. Some felt that there was a need for bodies funding research and training to play a more active role in directing effort into tl-mse areas where it was most needed. The necessity for training a body of skiltcd personnel in the techniques of offshore development was also recognized. There is already a considerable trade in the exportation of expertise, in fields such as fisheries management and This trade could be hydrography. expanded, both providing a source of revenue for the funding of work in UK waters and in exchange for access to the offshore resources of other states. the
The necessity for providing a stable &mate encouraging investment in offshore operations was stressed by many participants. This means. for example, quickly resolving the outstanding international disputes over delimitation of the continental shelf and questions of the applicability of UK law to offshore activities, in order to maintain the inornentuill of the oil industry. Similarly. it is necessary to formulate an EEC fishing policy accommodating the British industry fishing. Several speakers etnphasized the desirability of continuing to negotiate bilateral fishery treaties, despite n~ernb~rsliip of the EEC. in order to the flexibility of approach retain neccssnr\ to the soluGon of this complex problem. Again. in some areas. such as fish farming and ranching, the Iah’ has so far failed to provide the framework of protection necessary to induce commercial investment. The present uncertainty of the legal positions of developers was thought to be a major restraint on investment and future planning in an area which demanded heavy capital investment and so long-term certainty and security. Finally. it was generally felt that the level of public awareness of the opportuniGes and problems of offshore development should be heightened, both as a background to the evolution of a rational political policy on ocean management. and in order to encourage recruitment in the marine industries.
Centre for Marine University of Science
A.V. Lowe, Law and Policy,
of Wales Jnst~t~te and Techno/ogy, Cardiff, UK
Book reviews Impacts of a tidal barrage AN
ENVIRONMENTAL
OF THE SEVERN edited
APPRAtSAL
BARRAGE
by T.L. Shaw
of Civil Engineering, Department University of Bristol, 1977, 2nd ed, 155 pages,
72
f 3.00
The book represents an effort to come to grips with the array of environmental effects that would result from the implementation of the proposal to build a barrage across the Severn Estuary for the purpose of harnessing part of the enormous tidal energy available there. The editor deserves the gratitude of all
concerned with this massive (potentials project for having brought together papers covering a very wide range of problems. Indeed, one would be tempted to use the adjective ‘comprehensive’ were it not for the propensity of the natural environment to spring awkward surprises on us. In any event, it is impossible for this particular stranger to the Severn to see any omissions. If the volume has a most important message, it is that our knowledge of
MARINE
POLICY January 1978
Book revieirs what is actually going on in the estuary now and, a fortiori, our ability to predict what is likely to go on after such an enormous change in the underlying geography, are simply not on anything like a par with our ability to do the necessary civil engineering. True, none of the authors predicts catastrophic effects from the point of view of the UK as a whole, nor do any suggest that are even real such outcomes possibilities. Still, the degree of contradiction between chapters, and of within and uncertainty vagueness chapters is such that readers can only hope that the ‘further study’ called for by nearly every author is in fact undertaken before the project becomes an irrevocable stage in, for example, a post-North-Sea energy plan.
Tidal effects In counterpoint to this almost constant note of great uncertainty, a few environmental effects of greater or less specificity are set out in quite definite terms. Most predictable, because of our the underlying understanding of mechanisms and our ability to model the resulting processes mathematically, are the effects of the barrage on tides, both above and below the barrier (Chapter 2, by Miles and Webb of the Hydraulics Research Station). In general, it appears there will be some small changes in the tidal regimes of the outer estuary, St George’s Channel, and the Irish Sea, most of these being small amplifications of current ranges (though it is fascinating to the non-hydrologist to see that as far around Wales as Aberystwyth the tidal range is predicted to increase by about one quarter of a metre because of the barrage). As one would expect, the changes above the barrage are considerably more dramatic. For example, depend@ on which chapter one uses as a source of numbers, the dual-basin scheme proposed by Shaw is predicted to reduce the tidal range, at spring tides near Weston, from about lo-12 m (6 m above datum and 4 to 6 below) to roughly 3 m (6 m above datum to about 3 m above). From this striking change follows one other specific and unhedged prediction: the barrage is going to make continued drainage for agriculture of various low-lying pieces of land around
MARINE
POLICY
January
1978
the upper estuary very difficult and, indeed, impossible using the current method of tidal flaps. Pumping will have to be introduced - an additional cost of the project - or the land abandoned to marsh - a damage created by the project measurable in terms of agricultural net income lost (Chapter 4, by Tinkler of the Wessex Water Authority).
Effects on the ecosystem Beyond these observations, things are much less clear cut. Of course the tapping of tidal energy for electric power will result in a reduction in the energy expended in various ways in the estuarine environment during each cycle. This. no one doubts. will lead to a large amount of settling of solid particles which are now in more or less perpetual motion in the upper estuary. Muds are scoured and set in motion by the spring flood- and ebb-tide currents and at the times of peak tidal velocities are diffused through the entire water column giving nearly uniform turbidity levels as high as 10000ppm. As slack comes on these particles settle out and at slack form a kind of quasi-bottom waiting for the next cycle. The effects are similar but less large and pervasive during neaps (Chapter 3, by Kirby and Parker of the Institute of Oceanographic Sciences). The trouble is that no one is at all sure whether the settling will occur either generally by type of bottom topography, or specifica!ly by location _ and from this follows considerable initial uncertainty for the biologists and ecologists who would like to predict how the upper estuary’s ecosystem will change. Add to this boundary-condition uncertainty the tentative nature of aquatic ecology itself, and it is hardly surprising the authors of the principal biological/ecological chapters (Chapter 5, by Little of Bristol; 6, by Meetam of Cardiff; and 7, by Longhurst, Radford, and Undes of NERC Institute for Marine Environmental Research) are able to give us so few effect predictions of the ‘hardness’ of those relating to tides and associated physical drainage problems. It is, however, worth noting a few exceptions. If, in fact, the estuary behind the barrage clears up for the reasons just
mentioned, severe eutrophication may well result because of the large existing nutrient load, the increased flushing time for this ‘pond’, and the continued runoff from agricultural land in the basin. Such a result would have serious implications for the desirability of water-based recreation activities on the pond (as any boating enthusiast along the Potomac Estuary downstream of Washington, DC could testify). This possibility is unfortunately not mentioned by Wheatley of the South Western Sports Council in his final chapter on the recreation potential of the scheme. Furthermore, eutrophication might so deplete oxygen levels as to interfere with fish migrations in and out of the upper estuary. (This is quite separate from the influence of the barrier itself, which is discussed further below.)
Problems in prediction For the most part, however, the biological chapters are devoted to descriptions of populations and habitats currently existing in the estuary and to the suggestion of a number of events which ‘might’ happen. Chapter 7, describing an ongoing ecosystem modelling exercise at the Institute for Marine Environmental Research, does promise more, and promises it for the nottoo-distant future, as the various modules of the overall estuary model are completed and linked together. While I have every confidence that such work is vital to our future understanding of aquatic environments and their reactions to man-wrought changes. I would caution readers to be sceptical of the claims implicitly made here. The state of the art of quantitative ecology, not to mention that of the necessary mathematical solution techniques probably still leaves us with finished models which predict reasonably well population effects for phyto- and zooplankton, perhaps even with some differentiation by type, but which cannot be relied on for fish or for benthic communities and in which such problems as chronic toxicity are difficult or impossible to reflect.’ If the modellers are not quite through yet. and the more traditional types are very cautious about predicting biological effects, those who would tell
73
Book
reviecc’s
us what will happen to the larger and more obvious organisms might be expected to be in real difficulties. Thus, for example, J.H. Andrews of the Royal Society for the Protection of Birds, in Chapter 9, can tell us something about existing populations of wading birds, but in the predictive line can only ‘suggest the type of effects that could be produced’ (by the barrage). On the other hand, his conclusion suggests that the tentative quality of these comments is based on a misunderstanding, for he says. ‘It seems reasonable to suppose that the construction and operation of a tidal barrage would of itself be unlikely to have any significant effect on the wader populations, provided that there
was no interference in the natural tide range. It also seems clear that the greater such interference, the greater will be the direct and indirect impacts on the wader population’ (my emphasis). But as has already been pointed out, the one effect which can be foreseen with near certainty is that the tidal range will be greatly reduced and the average water level significantly increased over the entire upper estuary pond. Thus, this chapter leaves us wondering. The other bird chapter by Owen of The Wildfowl Trust) seems both confident and optimistic. The wildfowl of the estuary use it largely for roosting and feed ashore in any case, so that even dramatic changes in tide range and level, in the absence of heavy shoreside recreation and industrial development, will probably not have significant deleterious effects.
Fisheries The fisheries chapter (by Millichamp and Staite of the Welsh National Water Development Authority) is also rather startlingly straightforward and dramatic in its assessment and recommendation, given the poor quality of our understanding of the migratory mechanisms of the fish themselves and the uncertainties about what will really happen in the pond. But these authors correctly) see (probably quite themselves as advocates for the fishery, in which capacity they assert that depending on the turbine ports, or on these ports plus fish ladders, to get
migratory fish across the barrier in either direction is simply unacceptable. As an alternative, they recommend ‘the inclusion of a free gap within the structure sited close to the Welsh shore . It is envisaged that these free gaps would take the form of a break in the barrier through which up to 5% of the total in/outflow of the estuary would pass and which would be associated with an upsteam and downstream scour channel allowing movement at all states of the tide’. This suggestion. which calls to mind visions of incredible tidal currents with associated scouring endangering the flanks of the barrage on either side, is nowhere addressed by the tide and current modellers, though Shaw, in his introductory chapter, says the idea has much to recommend it.
Geology Chapters 12 through I6 of the book have to do with the geology of the area, including that of the estuary bed as it might affect construction and of the surrounding countryside as it holds implications for the availability of the massive quantities of rock, sand, and concrete required for construction. There is nothing here especially startling, and we are told that expansion of existing quarries would allow supply of the rock without unacceptable landside disturbance: that sand can be dredged from the area seaward of the proposed barrage; and that Wales might be marginally more attractive if some colliery shale were used in construction, as is physically feasible. All in all an impressive first step on the road to understanding the likely effects of this monster project. At the same time. the book could have been made even more valuable with just a little additional investment of effort. In particular, this volume would be much more useful to the average interested reader if an attempt had been made to produce a more self-contained work. At a minimum, it would be useful to have even the briefest of summaries of the other dimensions of the scheme in relation to the current (or projected) UK scene. Thus. what is the projected capital cost and how does it compare to current or projected CEGB capital budgets (or to other relevant budgets)?
What are the projected costs per kwh generated, and how do these compare with substitute sources such as nuclear plants? How much power can be attributed during daily peaks and how much pumping power will be needed at daily troughs and how do these quantities look next to the relevant load curves? Finally, the first chapter should explicitly describe the several schemes being proposed. and indicate how they differ in cost. output. effects on tides, etc. In the current version one is really forced to infer what these competing projects look like from the odd comment here and there and from a few before-and-after graphs of tidal fluctuations tacked on to Chapter 2, essentially without comment.
Broader canvas I am not, I hasten to emphasize, calling for a different book, a comprehensive project evaluation. It would be most unfair to refuse to accept this volume on its own terms - as an environmental appraisal. But if Shaw and the other authors hope to influence the public (and not-so-public) debate on the barrage proposal, they should recognize that all this information would be of even greater value were it seen in the context of costs and outputs (or benefits) and were the reader clear from the beginning that. for example, most authors are assuming a two-basin model which includes both use of the tides themselves and of pumped storage. Perhaps the next edition, since this is likely to be a long debate, will offer us a slightly broader canvas as backdrop as well as slightly firmer predictions. Clifford Resources
S. Russell,
for the Future, Washington,
DC, USA
‘Such an assessment of the state of the art was explicitly given and not contradicted at conference of the modellers, the proceedings of which have been published as Ecological Modelling in a Resource Management Framework, ed C.S. Russell, Resources for the Future, Washington, DC, 1975.
MARINE
POLICY
January
1978
Preoccupations Both in the papers and in the following days of discussion. in multidisciplinary working groups and in plenary sessions. Certain preoccupa&ions were evident. The present division of responsibilities in the UK for activities in and concerning the offshore zone between about 20 government felt to departments was widely necessitate the creation of a permanent within coordinating agency the government. Such an agency could not only reconcile the sometimes conflicting interests of departments in the use of the zone (for example, where dredging and fishing compete) but could also begin to streamline the system of administration of the offshore zone so as to minimize the number of departments with which intending developers of the zone would have to deal. The necessity for a coordinating agency arises from the unsuitability of the existing categories of activity and divisions of responsibility for planning
two
development of the seas. This necessity was also reflected in the general recognition that the policing of fisheries and oil rigs could not be seen as entirely military tasks forming part of the duties of the Royal Navy. It was thought better that the funding and organization of such policing duties should reflect the wide range of interests served by them. Similar views were expressed relation in the to Hydrographcr of the Navy. whose vital role in all offshore activities sometimes seems to be inadequately acknowledged. The present state of marine research in the UK caused some disquiet. The need to develop new techniques and technology for the exploitation of areas hitherto untouched, and for the better management of existing activities. is apparent. White there is much advanced work being done. many participants felt that closer liaison between public and private sector research. and between different establishments within sectors, would minimize duplication of effort and facilitate systematic examination of the many problems which remain to be solved. Some felt that there was a need for bodies funding research and training to play a more active role in directing effort into tl-mse areas where it was most needed. The necessity for training a body of skiltcd personnel in the techniques of offshore development was also recognized. There is already a considerable trade in the exportation of expertise, in fields such as fisheries management and This trade could be hydrography. expanded, both providing a source of revenue for the funding of work in UK waters and in exchange for access to the offshore resources of other states. the
The necessity for providing a stable &mate encouraging investment in offshore operations was stressed by many participants. This means. for example, quickly resolving the outstanding international disputes over delimitation of the continental shelf and questions of the applicability of UK law to offshore activities, in order to maintain the inornentuill of the oil industry. Similarly. it is necessary to formulate an EEC fishing policy accommodating the British industry fishing. Several speakers etnphasized the desirability of continuing to negotiate bilateral fishery treaties, despite n~ernb~rsliip of the EEC. in order to the flexibility of approach retain neccssnr\ to the soluGon of this complex problem. Again. in some areas. such as fish farming and ranching, the Iah’ has so far failed to provide the framework of protection necessary to induce commercial investment. The present uncertainty of the legal positions of developers was thought to be a major restraint on investment and future planning in an area which demanded heavy capital investment and so long-term certainty and security. Finally. it was generally felt that the level of public awareness of the opportuniGes and problems of offshore development should be heightened, both as a background to the evolution of a rational political policy on ocean management. and in order to encourage recruitment in the marine industries.
Centre for Marine University of Science
A.V. Lowe, Law and Policy,
of Wales Jnst~t~te and Techno/ogy, Cardiff, UK
Book reviews Impacts of a tidal barrage AN
ENVIRONMENTAL
OF THE SEVERN edited
APPRAtSAL
BARRAGE
by T.L. Shaw
of Civil Engineering, Department University of Bristol, 1977, 2nd ed, 155 pages,
72
f 3.00
The book represents an effort to come to grips with the array of environmental effects that would result from the implementation of the proposal to build a barrage across the Severn Estuary for the purpose of harnessing part of the enormous tidal energy available there. The editor deserves the gratitude of all
concerned with this massive (potentials project for having brought together papers covering a very wide range of problems. Indeed, one would be tempted to use the adjective ‘comprehensive’ were it not for the propensity of the natural environment to spring awkward surprises on us. In any event, it is impossible for this particular stranger to the Severn to see any omissions. If the volume has a most important message, it is that our knowledge of
MARINE
POLICY January 1978
Book revieirs what is actually going on in the estuary now and, a fortiori, our ability to predict what is likely to go on after such an enormous change in the underlying geography, are simply not on anything like a par with our ability to do the necessary civil engineering. True, none of the authors predicts catastrophic effects from the point of view of the UK as a whole, nor do any suggest that are even real such outcomes possibilities. Still, the degree of contradiction between chapters, and of within and uncertainty vagueness chapters is such that readers can only hope that the ‘further study’ called for by nearly every author is in fact undertaken before the project becomes an irrevocable stage in, for example, a post-North-Sea energy plan.
Tidal effects In counterpoint to this almost constant note of great uncertainty, a few environmental effects of greater or less specificity are set out in quite definite terms. Most predictable, because of our the underlying understanding of mechanisms and our ability to model the resulting processes mathematically, are the effects of the barrage on tides, both above and below the barrier (Chapter 2, by Miles and Webb of the Hydraulics Research Station). In general, it appears there will be some small changes in the tidal regimes of the outer estuary, St George’s Channel, and the Irish Sea, most of these being small amplifications of current ranges (though it is fascinating to the non-hydrologist to see that as far around Wales as Aberystwyth the tidal range is predicted to increase by about one quarter of a metre because of the barrage). As one would expect, the changes above the barrage are considerably more dramatic. For example, depend@ on which chapter one uses as a source of numbers, the dual-basin scheme proposed by Shaw is predicted to reduce the tidal range, at spring tides near Weston, from about lo-12 m (6 m above datum and 4 to 6 below) to roughly 3 m (6 m above datum to about 3 m above). From this striking change follows one other specific and unhedged prediction: the barrage is going to make continued drainage for agriculture of various low-lying pieces of land around
MARINE
POLICY
January
1978
the upper estuary very difficult and, indeed, impossible using the current method of tidal flaps. Pumping will have to be introduced - an additional cost of the project - or the land abandoned to marsh - a damage created by the project measurable in terms of agricultural net income lost (Chapter 4, by Tinkler of the Wessex Water Authority).
Effects on the ecosystem Beyond these observations, things are much less clear cut. Of course the tapping of tidal energy for electric power will result in a reduction in the energy expended in various ways in the estuarine environment during each cycle. This. no one doubts. will lead to a large amount of settling of solid particles which are now in more or less perpetual motion in the upper estuary. Muds are scoured and set in motion by the spring flood- and ebb-tide currents and at the times of peak tidal velocities are diffused through the entire water column giving nearly uniform turbidity levels as high as 10000ppm. As slack comes on these particles settle out and at slack form a kind of quasi-bottom waiting for the next cycle. The effects are similar but less large and pervasive during neaps (Chapter 3, by Kirby and Parker of the Institute of Oceanographic Sciences). The trouble is that no one is at all sure whether the settling will occur either generally by type of bottom topography, or specifica!ly by location _ and from this follows considerable initial uncertainty for the biologists and ecologists who would like to predict how the upper estuary’s ecosystem will change. Add to this boundary-condition uncertainty the tentative nature of aquatic ecology itself, and it is hardly surprising the authors of the principal biological/ecological chapters (Chapter 5, by Little of Bristol; 6, by Meetam of Cardiff; and 7, by Longhurst, Radford, and Undes of NERC Institute for Marine Environmental Research) are able to give us so few effect predictions of the ‘hardness’ of those relating to tides and associated physical drainage problems. It is, however, worth noting a few exceptions. If, in fact, the estuary behind the barrage clears up for the reasons just
mentioned, severe eutrophication may well result because of the large existing nutrient load, the increased flushing time for this ‘pond’, and the continued runoff from agricultural land in the basin. Such a result would have serious implications for the desirability of water-based recreation activities on the pond (as any boating enthusiast along the Potomac Estuary downstream of Washington, DC could testify). This possibility is unfortunately not mentioned by Wheatley of the South Western Sports Council in his final chapter on the recreation potential of the scheme. Furthermore, eutrophication might so deplete oxygen levels as to interfere with fish migrations in and out of the upper estuary. (This is quite separate from the influence of the barrier itself, which is discussed further below.)
Problems in prediction For the most part, however, the biological chapters are devoted to descriptions of populations and habitats currently existing in the estuary and to the suggestion of a number of events which ‘might’ happen. Chapter 7, describing an ongoing ecosystem modelling exercise at the Institute for Marine Environmental Research, does promise more, and promises it for the nottoo-distant future, as the various modules of the overall estuary model are completed and linked together. While I have every confidence that such work is vital to our future understanding of aquatic environments and their reactions to man-wrought changes. I would caution readers to be sceptical of the claims implicitly made here. The state of the art of quantitative ecology, not to mention that of the necessary mathematical solution techniques probably still leaves us with finished models which predict reasonably well population effects for phyto- and zooplankton, perhaps even with some differentiation by type, but which cannot be relied on for fish or for benthic communities and in which such problems as chronic toxicity are difficult or impossible to reflect.’ If the modellers are not quite through yet. and the more traditional types are very cautious about predicting biological effects, those who would tell
73
Book
reviecc’s
us what will happen to the larger and more obvious organisms might be expected to be in real difficulties. Thus, for example, J.H. Andrews of the Royal Society for the Protection of Birds, in Chapter 9, can tell us something about existing populations of wading birds, but in the predictive line can only ‘suggest the type of effects that could be produced’ (by the barrage). On the other hand, his conclusion suggests that the tentative quality of these comments is based on a misunderstanding, for he says. ‘It seems reasonable to suppose that the construction and operation of a tidal barrage would of itself be unlikely to have any significant effect on the wader populations, provided that there
was no interference in the natural tide range. It also seems clear that the greater such interference, the greater will be the direct and indirect impacts on the wader population’ (my emphasis). But as has already been pointed out, the one effect which can be foreseen with near certainty is that the tidal range will be greatly reduced and the average water level significantly increased over the entire upper estuary pond. Thus, this chapter leaves us wondering. The other bird chapter by Owen of The Wildfowl Trust) seems both confident and optimistic. The wildfowl of the estuary use it largely for roosting and feed ashore in any case, so that even dramatic changes in tide range and level, in the absence of heavy shoreside recreation and industrial development, will probably not have significant deleterious effects.
Fisheries The fisheries chapter (by Millichamp and Staite of the Welsh National Water Development Authority) is also rather startlingly straightforward and dramatic in its assessment and recommendation, given the poor quality of our understanding of the migratory mechanisms of the fish themselves and the uncertainties about what will really happen in the pond. But these authors correctly) see (probably quite themselves as advocates for the fishery, in which capacity they assert that depending on the turbine ports, or on these ports plus fish ladders, to get
migratory fish across the barrier in either direction is simply unacceptable. As an alternative, they recommend ‘the inclusion of a free gap within the structure sited close to the Welsh shore . It is envisaged that these free gaps would take the form of a break in the barrier through which up to 5% of the total in/outflow of the estuary would pass and which would be associated with an upsteam and downstream scour channel allowing movement at all states of the tide’. This suggestion. which calls to mind visions of incredible tidal currents with associated scouring endangering the flanks of the barrage on either side, is nowhere addressed by the tide and current modellers, though Shaw, in his introductory chapter, says the idea has much to recommend it.
Geology Chapters 12 through I6 of the book have to do with the geology of the area, including that of the estuary bed as it might affect construction and of the surrounding countryside as it holds implications for the availability of the massive quantities of rock, sand, and concrete required for construction. There is nothing here especially startling, and we are told that expansion of existing quarries would allow supply of the rock without unacceptable landside disturbance: that sand can be dredged from the area seaward of the proposed barrage; and that Wales might be marginally more attractive if some colliery shale were used in construction, as is physically feasible. All in all an impressive first step on the road to understanding the likely effects of this monster project. At the same time. the book could have been made even more valuable with just a little additional investment of effort. In particular, this volume would be much more useful to the average interested reader if an attempt had been made to produce a more self-contained work. At a minimum, it would be useful to have even the briefest of summaries of the other dimensions of the scheme in relation to the current (or projected) UK scene. Thus. what is the projected capital cost and how does it compare to current or projected CEGB capital budgets (or to other relevant budgets)?
What are the projected costs per kwh generated, and how do these compare with substitute sources such as nuclear plants? How much power can be attributed during daily peaks and how much pumping power will be needed at daily troughs and how do these quantities look next to the relevant load curves? Finally, the first chapter should explicitly describe the several schemes being proposed. and indicate how they differ in cost. output. effects on tides, etc. In the current version one is really forced to infer what these competing projects look like from the odd comment here and there and from a few before-and-after graphs of tidal fluctuations tacked on to Chapter 2, essentially without comment.
Broader canvas I am not, I hasten to emphasize, calling for a different book, a comprehensive project evaluation. It would be most unfair to refuse to accept this volume on its own terms - as an environmental appraisal. But if Shaw and the other authors hope to influence the public (and not-so-public) debate on the barrage proposal, they should recognize that all this information would be of even greater value were it seen in the context of costs and outputs (or benefits) and were the reader clear from the beginning that. for example, most authors are assuming a two-basin model which includes both use of the tides themselves and of pumped storage. Perhaps the next edition, since this is likely to be a long debate, will offer us a slightly broader canvas as backdrop as well as slightly firmer predictions. Clifford Resources
S. Russell,
for the Future, Washington,
DC, USA
‘Such an assessment of the state of the art was explicitly given and not contradicted at conference of the modellers, the proceedings of which have been published as Ecological Modelling in a Resource Management Framework, ed C.S. Russell, Resources for the Future, Washington, DC, 1975.
MARINE
POLICY
January
1978