Floods and Drainage

British Policies for Hazard Reduction, Agricultural Improvement and Wetland Conservation

Edmund Penning-Rowsell

• Publisher: Taylor & Francis
• Year: 2019
• Print ISBN: 9780367420604
• eBook ISBN: 9781000753639
• Edition: 1
• Topic: Biological Sciences
• Subtopic: Ecology
• Index: Biological Sciences

Originally published in 1986, Floods and Drainage advanced hazard – response theory as developed mainly by the White/Burton/Kates school of researchers in North America. Based on fifteen years of research, the book rejects conventional theory's emphasis on personal response to hazardous environments, suggesting that this seriously detracts from the institutional and political forces that are so important in the analysis of hazard responses and policies. The book also seeks to provide material of practical relevance to environmental managers and engineers, rather than to present just research results.

1Flood alleviation and agricultural land drainage

Introduction

Urban flood alleviation and agricultural land drainage are inseparable in Britain. In many parts of the country the soil-water regime inhibits agricultural use. Increasing agricultural production here depends, therefore, upon the provision of adequate field drainage. This in turn depends on having adequate discharge capacity in the network of interconnecting drainage channels and rivers downstream. These rivers and channels often pass through urban areas and can cause flooding. Towns and cities in turn may discharge their rapid storm runoff through further agricultural areas, again perhaps causing flooding or preventing field drainage.

Both urban and rural flood alleviation or drainage must therefore be viewed in concert because the one may exacerbate the other’s problems. As well as being hydrologically interdependent, the two aspects of drainage are also institutionally linked in Britain. This reflects many decades of experience of these hydrological interlinkages and thus a keen appreciation of the advantages of undivided field-to-coast river catchment management by single land drainage agencies.

Our complementary analysis of policies to reduce flood hazards and agricultural drainage problems emphasises that the management of such hazards is concerned with the utilisation or exploitation of natural resources. A fundamental objective of flood hazard reduction and land drainage schemes is thus improving the use of land. The process is complex, however, in that the balance of environmental systems is being disturbed. Consequences may be inadvertent and unpredictable. Drainage schemes may enhance land values for one purpose but devalue the same land for other uses. Flood hazard management therefore involves complex trade-offs between alternative resource gains and losses.

Flood alleviation and land drainage are fundamentally about planning public expenditure to increase social welfare. Urban and agricultural drainage schemes are designed to improve the nation’s welfare in much the same way as are hospitals, education and the social services. The aim is to reduce flood damage, enhance agricultural productivity and thereby to promote greater prosperity by ensuring the security of property, a healthy workforce, and efficient business, including farming, through the provision of adequate infrastructure including drainage.

This volume aims, in this context, to elaborate on the inseparability of flood hazard reduction and agricultural land drainage in Britain, with all the complications – and interest – that this linkage brings to our analysis of policies and decision making. Secondly, we aim to show that a multidisciplinary approach to policy analysis and problem solving is necessary for progress. For appropriate policies and good management practices those making decisions need to combine theories and information from environmental science, engineering, institutional analysis, economics, decision making and planning.

A third aim is to attempt to fit hazard reduction and land drainage into a wider analysis of the relevant political economy of Britain today. This is necessary because the policies being pursued are inseparable from this wider context and cannot properly be understood in isolation. Through pursuing these emphases we aim, fourthly, to contribute a new perspective on hazard-response theory which brings together into a common framework the analysis of two complementary hazards and emphasises the institutional and political influences upon the decision-making process.

Flooding and land drainage problems in Britain:
the environmental context

Britain has a temperate cyclonic climate giving predominantly winter rainfall averaging some 1000 mm per annum (Manley 1952; Meteorological Office 1973; Rodda et al. 1976, Chandler & Gregory 1976). Intensive storms and floods are caused by westerly depressions with well-developed warm fronts or by summer convectional thunderstorms (Ward 1975, 1978, Smith 1972). Rapid winter snow-melt in changeable weather regimes can also produce serious flood conditions. High levels of water retention in lowland clay soils, together with the low evapotranspiration rates in a cool moist climate, result in a relatively long season of soil waterlogging. The extensive low-lying areas in eastern England with naturally high water tables also present continual drainage problems. Large and extensively paved urban areas, again particularly in England, can produce rapid runoff and sudden floods (Hollis 1975, 1979). Because catchments are relatively small, most British rivers tend to be ‘flashy’ in nature giving very little time for flood warnings (Lewin 1981).

Although they are diverse, most British flood and drainage problems are perhaps relatively minor by world standards; fortunately loss of life in floods is comparatively rare. Nevertheless Britain has a long tradition of both flood alleviation and agricultural land drainage (Johnson 1954, Cole 1976). Analytical techniques have developed further than in most countries, and institutional arrangements have evolved and matured over many generations. The result is that annual expenditure in this field is currently about £80 million (1981–2). The ratio of expenditure on agricultural and urban drainage improvement is approximately 40 : 60 and nearly all is for England and Wales. Scotland suffers from few major flood or drainage problems, despite a wetter climate, because a smaller population means less pressure on land and less intensive use of floodplains.

The causes of British urban flood problems are varied. The historic cores of many of the older British towns were located adjacent to river floodplains to capitalise upon defensive locations and natural lines of communication. Subsequent development during periods of urban expansion has tended to be on flood-prone land (Penning-Rowsell & Parker 1974). Such floodplain encroachment occurred principally during the 19th century, but it also occurred in the 20th century before the Town and Country Planning Act 1947 created a universal land-use planning system to control urban development (Penning-Rowsell 1981a). Although this legislation was not specifically enacted to control floodplain encroachment, the Act and subsequent government circulars (Ch. 2) have largely been successful in limiting extensive development of floodplains. The hazards from pre-existing encroachment have remained, however, in those locations where structural flood alleviation schemes have not been implemented or are of insufficient standard. Urban floodplain encroachment continues as a nagging but ill-defined problem, although it is on nothing like the scale found in the United States where general floodplain regulations or zoning systems have yet to be adopted (Parker & Penning-Rowsell 1983).

Besides major urban encroachment of floodplains resulting from the pre-1947 urban expansion, as in the lower parts of the Thames catchment west of London, numerous smaller flood problems also exist. Many arise because British urban drainage systems are commonly decades or centuries old, highly modified and inadequate for today’s increased runoff from dense urban development and improved agricultural land drainage. Urban watercourses have commonly been culverted or piped underground and combined with underground storm drainage and sewerage systems which may now be inadequate to discharge peak flows. The result is disruptive flooding from unpredictable storm runoff, the reduction of which will be costly in terms of improved or replacement drainage capacity.

Large areas of eastern England are close to or below sea level and are comparable in some cases to the polderland areas of the Netherlands (see Fig. 2.3). Major drainage systems have been developed during the past 200 years. At first these were powered by wind pumps and later by steam, diesel and electric pumps in conjunction with thousands of kilometres of artificial arterial drainage channels and dykes (Darby 1940, 1983). Water tables have been lowered so that bog, mere and marsh soils have been converted into more valuable agricultural land by capitalising upon the reduction in flooding frequency. English drainage expertise – itself partly learned from Dutch engineers – originated largely in these Fens but wetlands elsewhere in the country have been drained progressively to improve agricultural productivity.

Field drainage is now considered a basic requirement for efficient farming on over half of the 11 million hectares of agricultural land in England and Wales. Cole (1976) suggests that the use of a further 3 million hectares is constrained by poor drainage and that completing the necessary drainage improvements for this land will require major river improvement works. However, the environmental impact of continual agricultural and urban drainage improvements has become a major environmental issue in Britain. Wetland habitats have become progressively scarcer and therefore increasingly valued (Penning-Rowsell 1980, 1983a).

Because so much of eastern England is low-lying, sea flooding is a major problem, especially from the Humber estuary to Kent (Steers 1953, Ward 1978). The threat is from a combination of high tides, low pressure over the North Sea and strong onshore winds which lead to tidal surges. Disastrous floods occurred in 1953 when 300 people were killed and property losses amounted to some £30 million (approximately £250 million at 1983 prices). Unfortunately eastern England is falling relative to sea levels and the 1953 event came close to being repeated in 1978, thus emphasising the need for continual re-evaluation of east coast sea defences against a growing risk. Raising these defences, however, requires massive expenditure and new technology in the form, for example, of tidal exclusion barriers such as those installed in the Thames estuary to protect London (Horner 1979). Decisions must therefore involve the most careful evaluation of the risks, costs and the adverse impacts of such ventures.

The welfare products of flood alleviation and land drainage

Flood alleviation and land drainage are fundamentally about planning public expenditure to increase social welfare by reducing the type of flooding and drainage problems described above. This raises questions concerning why public expenditure is necessary in this field – why should the state be involved? – and how should decisions be made concerning social welfare? In tackling these questions we have to disentangle the rhetoric of government and policy makers from the reality as experienced by those affected by flooding and drainage problems and by those involved in planning the drainage improvements.

THE CASES FOR STATE INTERVENTION

Much research into human response to floods has its origins in the Chicago school of geographers who primarily emphasised the role of the individual in making adaptation decisions to counter the hazards they face (Kates 1962, 1970, Burton et al. 1978). Nevertheless in Britain, as in most countries, the dominant flood alleviation and land drainage policies are government sponsored and supposedly oriented towards achieving community goals. Raising overall social welfare – the product of all individuals’ welfare – is the objective and state intervention and community funds can therefore be justified. Given the free-enterprise ethic in a predominantly capitalist economy, helping the individual is only undertaken as a means to helping all. This, at least, is the rhetoric.

The case for state intervention is multifaceted. In Britain today the scope for individuals to reduce their own exposure to flood hazards is strictly limited, although the individual farmer’s role in agricultural drainage is quite crucial. Firstly, it is generally not technically possible or economic to provide flood alleviation for individual property owners or agricultural drainage for just one farm. Flood alleviation is an indivisible commodity. It affects other parts of the river system and also can be provided most efficiently in large quantities. Levées can be built around individual buildings, but community land-use control and overall river regulation or flood warning systems are generally more cost-effective and reliable. The water table of one agricultural area cannot be lowered unless neighbouring areas are affected: the hydrological system cannot easily be subdivided to coincide with property boundaries. Such hydrological interlinkages mean that collective rather than individual decisions are required. The state is invoked to seek agreement, comparable technical standards, and, consequently, the maximisation of social welfare rather than the possible anarchy of individual response.

A further reason for state intervention arises because in most communities only a minority are affected. The state’s role, therefore, is to channel subsidy to this unfortunate minority. This argument for intervention is reinforced because, as with most natural disasters, flooding most affects those least resilient to its effects. Such people are typically those least capable of withstanding the financial impact of flood damage and least able to use technical arguments and political pressure to reduce their vulnerability. The impacts of flooding therefore tend to be selective, thereby widening inequalities between the rich and poor, the young and the old. Although there are obvious exceptions, those at risk in Britain from repeated flooding tend to be poorer than the national average. Flood alleviation can thus be redistributive by safeguarding the vulnerable at the expense of those already insulated from financial loss or the other adverse effects of flooding.

Irrespective, however, of such redistributive arguments a pervading attitude is that floods are natural ‘Acts of God’ and not the fault of those at risk. The state, therefore, intervenes on behalf of the unaffected community to rescue those afflicted who, as individuals, could not afford the protection they need. This is the ‘welfare state’ case for intervention: helping those who appear blameless for their own fate and thus, incidentally, helping to redress the ‘natural’ imbalances in an inegalitarian world.

A final reason put forward for state intervention in the land-drainage field is to promote increased agricultural production, subsidise investment and thus protect the profitability of farming. Such a reason perhaps contradicts the previous one – helping disadvantaged minorities – since those farmers who benefit most from subsidised investment tend to be those with the capital available to contribute their share. In any case, lowland farmers are amongst those most affluent in Britain. Nevertheless, increasing the profitability of the individual farm unit with investment in both new machinery and land improvement through drainage is seen by government as the means by which the collective good of increased food production can be attained. Main river arterial works are generally required, which the individual farmers perhaps could not finance and from which others concerned will benefit. The community, therefore, invests to seek a community-wide return. The consequent increased food production can reduce the cost of food imports and their adverse effect on the nation’s balance of payments. The policy thereby seeks to enhance national – or European Community – self-sufficiency and security in a world where food is a scarce commodity carrying significant political power.

WELFARE PERSPECTIVES AND POLITICAL ANALYSIS

Flood hazards can cause misery and loss of life and may threaten personal health and family financial security...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Dedication
• Table of Contents
• Foreword
• Preface
• Acknowledgements
• List of figures
• List of tables
• 1 Flood alleviation and agricultural land drainage
• 2 The institutional context
• 3 The hydrologic, hydraulic and hydrographic analysis of flooding and land drainage problems
• 4 The economics of flood alleviation and land drainage
• 5 Environmental impacts and conservation policies
• 6 Consultation: power, interests and attitudes
• 7 Fundamentals
• Bibliography
• Index
• General Index