摘要
The health of river basins throughout the world is under pressure from economic activities and a changing climate. Water is necessary for life, agriculture and many industrial production processes. But water is also a receptor for our waste products. In Europe, diffuse pollution from agriculture and our industrial legacy, together with hydraulic engineering for navigation, water supply, hydroelectricity or flood control, is seen as the main factor adversely influencing the quality and ecology of European freshwaters and estuaries. Economic activities affect the chemical and ecological status of our rivers, lakes and groundwater and deplete available soil–sediment–water resources. The wide range of economic activities and the ecohydrological complexity of many river basins, in terms of the functioning of the soil–sediment–water system and the links between water quantity, quality and economic activities, make a more integrated management approach to river basins complex and challenging. As the pressures from both anthropogenic and natural causes on environmental systems increase, it is no longer effective or efficient to deal with one issue at a time, since solving a singular problem often causes damaging impacts on other environmental compartments or in other places. We must consider the consequences of our actions on all parts of the environment in an integrated way and configure these actions to cope with an uncertain future. These challenges demand a different approach in order to achieve actual improvement of the ecological quality of our river basins and thus sustain the goods and services they provide for the well-being of society. Risk-informed management is this new approach. It involves the integrated application of three key principles: be well informed, manage adaptively and take a participatory approach. Be Well Informed: This implies that a sound understanding of the functioning of the soil–sediment–water system (ecosystem) and its interaction with the social system is the basis to river basin management. A range of European Commission (EC) Framework Programme projects, like AQUATERRA and MODELKEY, have helped deliver, through a range of applied tools, new ecosystem understanding at the site-specific, catchment and river basin scales. For instance, they produced evidence that ecosystem functioning is threatened by contaminants, such as pesticides, nutrients and metals, that are propagated via groundwater pathways from the land surface to rivers, lakes and the sea. Furthermore, there is also evidence that this functioning is threatened by historic contamination mobilised by extreme floods from sediments within rivers, on riverbanks or in floodplain soils. The first generation of river basin management plans (published end of 2009) has only rarely included targeted measures to mitigate these risks. However, the Water Framework Directive (WFD, Annex IV) demands that such system understanding should be integrated in the first (to be published in 2015) or subsequent updates of these plans. Manage Adaptively: Using our best available understanding on how river ecosystems function will certainly improve river basin management. However, when using scenarios—like the Intergovernmental Panel on Climate Change (IPPC) Special Report on Emission Scenarios (SRES)—or other tools to frame plausible trajectories of change, uncertainties will always remain. This is intrinsic to social as well as ecological systems. Systems, especially at larger scales, are extremely complex and dynamic and can respond in non-linear and unexpected ways. We may be able to cope with these uncertainties by applying the concept of adaptive management, characterised as ‘learning-by-doing-or ‘learning to manage by managing to learn- In addressing changes in climate and hydrology, the EC Framework Programme project NEWATER delivered guidance to apply the concept in practice. Take a Participatory Approach: Participatory processes involve stakeholders in management and aim to enable them to exchange their views and opinions on problems and bring their knowledge to the table. By learning together to understand the land–water system in a better way, better solutions can be found. This process of social learning requires a common language. The rapidly developing ecosystem services approach may provide that language. A common understanding of the value of the goods and services that a healthy ecosystem can provide, and how their present poor status due to our actions can be improved, is the key to a new approach to river basin management. The WFD recognises several of these aspects. It is both risk-informed and ecologically centred. It also recognises the need to balance improvements to water and ecosystem quality with economic benefits including the need to supply water for human requirements. Increasingly, governments also see the need to grow and supply food as part of the balancing act we have to make. Some examples from practice are already available where integration of these three key principles is attempted. They show very encouraging results and may inspire others. However, it is our conviction that well-designed, coordinated and monitored ‘learning catchments-(i.e. aimed at stepwise improvement of the effectiveness of measures) are needed to transform our general framing and develop best practice. The International Risk Governance Council’s (IRGC) risk governance framework is recommended as a source of inspiration for the design and execution of such learning catchments.