River channel improvement

River improvement accentuates flooding.

River works were brought under special legislation at an early date, because they affect all riparian land owners. In Britain the legal principles which were applied to Romney Marsh in the thirteenth century were extended to the whole country by the 1531 Bill of Sewers. It remains 'the basis of all drainage legislation' (Report of the Royal Commission on land drainage in England and Wales 1927) and established the principle that every landowner who benefits from a river improvement can be required to contribute to the cost of the works. The Sewers Act of 1833 gave Commissioners powers to define drainage districts, levy a rate, and spend the money on drainage. This Act resulted in considerable land drainage activity but did not provide sufficient funds for improvements to main rivers, because the people who benefitted from the scheme were taken to be those with land below, or just above, the highest known flood level. Upstream drainage without downstream river widening caused severe flooding. In 1877 a Select Committee of the House of Lords reported that: It is evident to the Committee, from the information which has been laid before them, that considerable damage has been caused in various parts of England by the prevalence of floods during the last winter, and that such floods have been more frequent and of longer duration in recent times than formerly. Among the causes which have been assigned for this state of things, the Committee find that prominence is given to the very general adoption of the system of subsoil drainage, owing to which a greatly augmented quantity of water is rapidly carried into rivers, and to the deterioration which is constantly taking place in the channels of the rivers themselves whereby they are rendered inadequate to carry off the water of their respective watersheds (Report of the Select Committee 1887). No action was taken until a Royal Commission on Land Drainage reached the same conclusion in 1927. It reported that owners of higher land were thought to have 'a natural right to discharge their water into the lower levels', where owners then had 'to expend vast additional sums on protective measures in the shape of barrier banks and on increased outfall facilities' (Report of the Royal Commission on land drainage in England and Wales 1927). The 1927 report was followed by a Land Drainage Act in 1930. New authorities, known as Catchment Boards, were given powers to levy rates on whole catchments, and to spend the money on improvements to main rivers. Use of the term 'catchment' instead of 'watershed' indicates a human-centred approach. 'Upland' landowners, with property above the highest flood level, had to contribute towards the cost of improving rivers in 'lowland' areas. The 1930 Act led to a great increase in the number of river improvement schemes. Catchment Boards began work at river estuaries and progressed upstream. Their work was continued by the River Boards after 1948 and by the Water Authorities after 1973. Authority for river work was then passed to the National Rivers Authority in 1989 and to the Environment Agency in 1996. These agencies have a wider brief and a more enlightened approach. From 1930ï¾­1940 'so much tree clearance was done' that in 1954, E.A.G Johnson, the Ministry of Agriculture's Chief Engineer, said it was 'difficult to get a complete picture of the derelict state of the rivers before the passing of the Land Drainage Act of 1930' (my italics). Tree clearance also removed shade and, in Johnson's opinion, led to the growth of water weeds 'which could form an even greater obstruction than much of the tree growth' (Johnson 1966: 44). Since the 1960s water weeds have been controlled by herbicides but the policy has been very unpopular with conservation and wildlife groups. In 1954 Johnson said that 'great care is now taken to remove only those trees which form a definite obstruction to flow', but in 1969, still most unhappy about the effect of engineering work on rivers, Johnson wrote that 'in far too many places developments have had little regard either to the existing or potential amenity value of rivers. Indeed, in far too many places rivers and streams have been regarded as nuisances, something to be culverted, enclosed between factory walls or between the fencedï¾­in back gardens of houses' (Johnson 1969). Johnson's views were a welcome contrast to the traditional engineering approach. Nixon, as Chief Engineer to the Trent River Authority in 1966, used that remarkable old term 'training' in an article on his authority's approach to rivers (Nixon 1966). He illustrates the approach with photographs of 'trained' rivers. They are encased in concrete or confined between parallel berms, like the unfortunate River Crouch at Wickford [Fig 9.4]. Nixon described it as a River Improvement Scheme but one can see that, whatever else may have been improved, most certainly it was not the river. His visual insensitivity is further revealed by the technocratic judgement that precast concrete blocks look 'more pleasing than natural stone pitching'. Seeing plants as 'weeds' and animals as 'pests', he is a fine example of blinkered single-purposism. Throughout Europe and North America river 'improvement' schemes have followed the same pattern [Fig 9.5], so that 'the vast majority of rivers and streams have been regulated, straightened, misused, polluted, canalised or even piped' (Garten & Landscahft, 1983). The US Council on Environmental Quality, in a 1973 report on riverworks, estimated that the Corps of Engineers, the Bureau of Reclamation and the Tenessee Valley Authority had constructed 13,358 km of flood defences and 8,047 km of 'channel improvements' on main rivers, while the Soil Conservation Service and the Corps of Engineers had 'channelized' 55,104 km of streams (Dunne & Leopold 1978). Dunne and Leopold state that the works tend to cause channel instability, downstream bank erosion, bed degradation or aggradation, aesthetic despoliation, and damage to fauna and flora. They suggest an alternative approach: Channel changes in urban streams cause costly construction and maintenance and unsightly, dangerous conditions. Many a small stream though an urban area will be seen encased in concrete, lined with a high, strong wire fence to keep children from falling into the fastï¾­moving water during storm flow. An alternative design might well have been a streamï¾­side park with bicycle paths, picnic places, attractive vegetation, and hydrologically desirable flood capacity that will tend to decrease rather than increase flooding downstream. Where this latter alternative is chosen, the urban creek can be an aesthetic amenity and a social asset. (Dunne & Leopold 1978)