Strategic management and planning within estuaries seeks to identify a framework that enshrines sustainability. Within the UK, a scoping exercise has been used to clarify user requirements and define the economic benefits that could be derived from a supporting programme of research. The programme recognises the need for a mix of fundamental, strategic and applied research, to address, in particular, issues of
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long-term change;
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physical, chemical and biological interactions and
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system response (including socio-economic interactions).
Achieving such a programme will need to take advantage of research at a number of different spatial and temporal scales. These span from global climate change initiatives, through catchment and estuary wide studies to work on specific features (banks, mudflats, etc.). They necessarily consider changes over time scales of seconds to aeons. Realistically, for strategic planning and management, the goal is to be able to predict, with a reasonable degree of confidence over a 20–50 year time horizon. Given the highly non-linear and complex adaptive nature of estuary systems, absolute predictions may not be possible. Rather, it will be necessary to identify probable/possible outcomes, or system states, as a basis for guiding management actions. This, in itself, will require managers and planners to move away from a prescriptive interventionist approach towards a more adaptive one.
Estuaries are a focal point for a wide range of human activities of increasing social and economic importance. The semi-enclosed basin that forms the estuary provides an area that is relatively sheltered, with a complex interplay of physical, chemical and biological processes, all of which are influenced by the marine environment and the surrounding catchment. With growing pressures comes the increasing risk that important habitats, such as mudflats and saltmarsh, will be lost or severely diminished.
Throughout history, man has settled near to the coastline and has used estuaries and rivers as a transport artery to inland areas. At first, estuaries were places of relative shelter and also provided a source of food and means of transport. As trading between different locations developed, ports grew up, initially as far inland as possible, since boats and ships offered the simplest form of transport. With time, ships have become larger so that the ports have moved progressively nearer the coastline where deeper water provides an economy of scale.
The industrial revolution increased the use of rivers and estuaries not only in transport of raw and finished goods but also in new uses, such as water extraction and discharges of waste. As populations grew there became a greater need for drinking water and the disposal of human waste, which was often taken from and/or discharged into rivers. Land for agriculture to feed the population and space for dwellings and industry was also required which led to reclamation or draining of low-lying areas. Thus, as man's ingenuity has evolved, increasing pressures have been imposed on the natural river and estuary system.
Today, there are probably relatively few estuaries (particularly in the developed world) which have not been affected in some way by man's intervention. Furthermore, this interaction has now been ongoing for many hundreds of years, although most significant effects have taken place in the last 100–200 years.
Anthropogenic effects are therefore a major agent influencing the morphology of an estuary either directly by means of engineering works and/or indirectly by modifying the physical, biological and chemical processes at work within the estuary. Since any change rarely has an instant effect, changes to the governing processes caused by an intervention in the past may not have completely worked through the system before further modifications are made thus increasing the complexity of the interactions. The timing of any anthropogenic effects relative to previous modifications along with the magnitude of the effect are important when trying to predict future estuary evolution.
With growing pressures, comes the increasing risk that the long recognised areas of nature conservation importance will be compromised and hence a much more proactive approach is being adopted towards positive management for future generations. Estuaries are also extensively used for recreational activities, such as sailing, fishing and walking. Conservation and recreation have the potential to both contribute to, and conflict with, social and economic development and as such require careful balancing. Hence, an integrated approach is needed to address multiple uses and interests, with sustainability central to the management process.
Within the UK, the use of scientific advice in decision making is an area that has recently been under close scrutiny and a more open and structured approach is now recognised as a necessary starting point [1]. For estuaries, there have been a number of initiatives to define the requirements for such a process and to set a research agenda to meet these needs. The starting point was the user needs and this in itself raised a number of apparent conflicts. Once distilled, this does however provide a rationale for a mix of fundamental, strategic and applied research on the various scales noted above, embracing traditional research themes, developing fields that arise from the study of complex, non-linear adaptive systems and a social–economic interface that is essentially fuzzy. This paper provides a review of the issues identified and some suggestions for the way forward.
