Waterways Conservation Research Paper

Rivers are dynamic components of environment because the quantity and the quality of the water alter, and the river channel itself can change position. It is partly because of this dynamic character, but also because of their resource value, that rivers have been managed deliberately by a range of direct and indirect influences so that few world rivers are now completely natural and unmodified, with more than 60 percent of the world’s total river flow being regulated. Recorded river modification began as early as 5,000 years ago with the advent of irrigation in the hydraulic civilizations of the Nile and the Indus basins. Subsequently there were many small-scale modifications of rivers for drainage schemes, fish weirs, water mills, navigation, and flotability, but the major control of rivers and river systems came with the Industrial Revolution when rivers were harnessed for industrial mills, power generation, cooling water, extensive irrigation, and water supply schemes. Technological advances in the twentieth century enabled even greater modification of rivers. For example, the impact of dam construction was relatively small until 1900, moderate to 1945, but substantial after the great increase of dam building between 1945 and 1971. Whereas in 1900 there were 427 dams higher than 15 m around the world, this increased to 5,268 in 1950 and to 39,000 in 1986 (ICOLD 1988). Building continues, for example, on the Qingjiang River, a tributary of the Yangtse, a large dam is planned for completion in 2009 at the same time as the Three Gorges dam in China. For the most part, however, the era of dam building came to an end in the developed world by the late 1980s and has been succeeded by the retirement of some dams.

Dam construction and engineering modification of waterways dominating the past 2 centuries followed from a ‘technological fix’ vision of the environment and its resources. More recently, conservation of rivers and waterways has become dominant, as has protection of the landscape more broadly to meet the needs of the present without compromising the opportunity for future generations (Newson 1992). This shift in management approach is illustrated by five themes pertinent to conservation of waterways.

1. Waterway Conservation

1.1 The Need To Control The Quantity Of Water In River Channels

The growth of human populations and changes in land use adjacent to rivers and waterways increases floods and flood damage from storm events. Increasingly, therefore, river management necessitates not only the modification of river channels to convey a design flow or calculated discharge of water, but consideration of a range of complementary strategies including flood control schemes, land-use zoning, and choice between big or small dams to retain flood waters according to the nature of the physical environment. Despite increased expenditure on flood control and greater understanding of the methods for flood assessment and mitigation, an increase in losses often follows flood events because of the assumption that the implemented scheme guarantees no flood damage (Smith and Ward 1998). A flood prevention scheme is designed for events of a certain magnitude and recurrence interval. Events of a larger magnitude or more frequent occurrence than the design are not uncommon. In addition, design usually considers maintenance of low flows to minimize the effects of drought upon water supply and river uses, such as fishing and recreation.

1.2 The Need To Control The Quality Of River Water

Waterways initially were seen as arteries to be used for disposal of waste products of society. The magnitude of waste has grown so large, however, that successive legislation has demanded more controls, to minimize the effects of serious levels of water pollution. Particular problems arise from point sources of pollution released into a river at an identifiable location, especially from wastewater treatment systems, industrial plants, agricultural pollution, and mining operations (National Research Council 1999). The culmination of such controls, for example, has witnessed the return of salmon to the Thames and Tyne rivers in the UK. Pollution is not always an easy problem to resolve because of the way in which pollutants relate to the sediment in the river channel. In northern New Mexico, for example, plutonium released from Los Alamos Laboratory on to nearby canyon floors was attached to sedimentary particles and in subsequent decades some of the sediments and the plutonium removed to the Rio Grande river raised concerns about environment and health hazards (Graf 1994).

1.3 The Need To Manage River Channels

River channelization involves modification, usually by engineering methods, for the purposes of flood control, drainage, navigation, and prevention of erosion. Direct channelization by engineering methods including straightening and reinforcing the bed and banks, led to the modification of the majority of lowland rivers in Europe over the past 2,000 years (Brookes and Shields 1996). Extension of channelization in the United States produced unwelcome consequences so that alternative schemes of river channel management were sought, including river restoration conceived as ‘working with the river rather than against it.’ Many river channels are now being restored to appear as ‘natural’ as possible and it is not unknown for rivers which were straightened by engineering to be ‘restored’ to their original meandering form. The difficulty in such restoration is to prescribe such dimensions of the restored channel as will enable the channel to contain flows likely to be very different in character from those existing before engineering channelization (Brookes and Shields 1996).

1.4 The Need To Acknowledge That River Restoration Involves More Than Returning A River Channel To Its Original Condition

The dynamic nature of the river channel must be considered, aided by identifying and conserving areas with special features as exemplars of typical waterways and also by educating the public about natural riverscapes. Restoration requires that river channels are managed with an awareness of the way in which they change and develop: the dynamic river must be seen against a timescale when there may have been considerable changes in palaeohydrology (Gregory et al. 1995). Consideration of what is natural is required because public perception does not always correspond with reality, especially in forested areas where woody debris is normal in river channels but public perception tends to prefer debris-free channels. Conserved areas provide an important reference designated as SSIs or sites of special scientific interest in the UK (Gregory 1997). In the US, the National Park Service (NPS) maintains high quality recreational areas and facilities, which include rivers and river access, through the ‘Rivers, Trails, and Conservation Program’ of the Department of the Interior. As societies move into post industrial stages, social values for rivers are changing from rivers as water resources to more complex multipurpose ecosystems or landscapes that potentially serve many objectives (Graf 1996).

1.5 The Need To Manage Rivers And Waterways Holistically Within The Drainage Basin

This need arose with the appreciation that river management in one area may have effects in other parts of the basin so that schemes of Integrated Basin Management (IBM) were devised. The modern development of water resource systems proceeded from single purpose projects through multipurpose schemes towards more integrated river basin planning. Important in progress towards more integrated planning was the development of the Tennessee Valley Authority (TVA), created as an independent federal agency from 1933 (National Research Council 1999). In order to achieve the two original primary purposes of flood control and navigation development, the Tennessee River and its tributaries were developed into one of the most controlled river systems in the world. Electric power is generated at the center of a suite of projects including navigational improvements and flood controls on the Tennessee River proper and soil erosion control, reforestation, improvement in agricultural land use, and increased and diversified industrial development elsewhere in the watershed. The TVA blazed the trail of integrated basin management. Downs et al. (1991), however, advocate distinguishing comprehensive river basin development where several components are involved, from integrated basin management where schemes interact, and from holistic management which dynamically incorporates energetics, change, and human interactions. The need to integrate consideration of ecological, as well as morphological and hydrological aspects, within a dynamic approach to river management and conservation, can be accomplished within an overall integrated approach. A new strategy for watershed management has been advocated in the US with drainage basins or watersheds as the basis for planning and management (NRC 1999).

Waterways which were once seen as elements of the environment to be conquered and tamed, are now seen as integral parts of dynamic evolving systems to be treated in a way that is sustainable and to be enjoyed and appreciated by future generations. A holistic view of rivers and waterways within the basin is the best basis for conservation, but sustainable management requires water users to make choices that cannot be made solely on the basis of scientific evidence, in part because the results of science may be ambiguous at times. In addition to scientific evidence, sustainable watershed management requires community under-standing and support. Therefore, IBM depends on partnerships between governments and the public, across disciplines and international borders, and among water users with different interests and values (Heathcote 1998). Paradoxically, as greater emphasis is placed on holistic approaches, the systems managed have been increasingly fragmented by human activity, for example into reaches controlled by dams with each reach exhibiting behaviour that can be markedly different from that of nearby reaches (Graf 1996). A further consideration necessary in relation to conservation is appreciation that rivers and waterways are valued in different ways by different cultures.

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