No abstract

No abstract

Social pressure on alluvial plains and deltas is large, both from an economic point of view and from a nature conservation point of view. Gradually, flood risks increase with economic development, because the expected damage increases, and with higher dikes, because the flooding depth increases. Global change, changing social desires, but also changing views, require a revision of flood-risk management strategies for the long term. These should be based on resilience as opposed to the resistence strategy of heightening dikes. Resilience strategies for flood-risk management imply that the river is allowed to temporarily flood large areas, whereas the flood damage is minimized by adapting land use. Such strategies are thus based on risk management and ʻ'living with floodsʼ' instead of on hazard control. For The Netherlands, one of the most densely populated deltas in the world, alternative resilience strategies have been elaborated and assessed for their hydraulic functioning and ʻ'sustainability criteriaʼ'.

In highly developed regions, ecosystems are often severely fragmented, whereas the conservation of biodiversity is highly rated. Regional and local actor groups are often involved in the regional planning, but when making decisions they make insufficient use of scientific knowledge of the ecological system that is being changed. The ecological basis of regional landscape change would be improved if knowledge-based systems tailored to the cyclic process of planning and negotiation and to the expertise of planners, designers and local interest groups were available. If regional development is to be sustainable, goals for biodiversity must be set in relation to the actual and demanded patterns of ecosystems. We infer a set of prerequisites for the effective use of biodiversity goal-setting methods in multi-stakeholder decision making. Among these prerequisites are the requirements that ecosystem patterns are set central and that methods integrate the demands of a suite of species, are spatially explicit, and allow the aspiration level to be modified during the planning process. The decision making must also be enriched with local ecological knowledge. The current methods for setting biodiversity targets lack crucial characteristicsin particular, flexibility-and often require too high a level of ecological expertise. The ecoprofile method we designed combines an ecosystem base with spatial conditions for species metapopulations. We report experiences with this approach in two case studies, showing that the method was understood by policy makers, planners, and stakeholders, and was useful in negotiation processes. We recommend experimenting with applying this approach in a variety of circumstances, to further improve its ecological basis.

Social pressure on alluvial plains and deltas is large, both from an economic point of view and from a nature conservation point of view. Gradually, flood risks increase with economic development, because the expected damage increases, and with higher dikes, because the flooding depth increases. Global change, changing social desires, but also changing views, require a revision of flood-risk management strategies for the long term. These should be based on resilience as opposed to the resistence strategy of heightening dikes. Resilience strategies for flood-risk management imply that the river is allowed to temporarily flood large areas, whereas the flood damage is minimized by adapting land use. Such strategies are thus based on risk management and 'living with floods' instead of on hazard control. For The Netherlands, one of the most densely populated deltas in the world, alternative resilience strategies have been elaborated and assessed for their hydraulic functioning and 'sustainability criteria'.

Policy makers are confronted with the question of how to combine sustainable flood protection and floodplain rehabilitation in the best possible way. Both topics deal with spatial planning aspects in a range of scales. This question was the starting point for the development of an evaluation method within the IRMA/SPONGE project Intermeuse, illustrated on the basis of assumed flood protection strategies in the Meuse river basin (the 'sponge' strategy, the 'retention' strategy, and the 'floodplain lowering' or 'winter bed' strategy). The integration of flood protection and floodplain rehabilitation can be performed on two scale levels that are interrelated: on the regional level the focus is on (large parts of) an entire stream basin; on the local level specific site conditions are taken as starting point. Ecological aspects under study are spatial cohesion of habitats as identified by species population persistence modelling (regional, longitudinal level) and required habitat quality for carabid beetles and for meadow vegetation gradients as assessed by correspondence analysis (local, transversal level). The carabid beetles are taken as indicative for the ecological integrity of the river bed, the meadow vegetation for that of the floodplain.A unifying concept in the evaluation of ecological integrity is the ecological minimum: the critical boundary or minimum level of habitat conditions for a potentially good ecological functioning. It is the least acceptable state for a river ecosystem that is still functional to some extent, compared to a natural river ecosystem. The results of this study show clearly that there is a good chance to combine floodplain rehabilitation aims with flood protection activities, both on a local and on an international scale. Although ecological effect assessment and ecological optimizing (referring to a natural reference state) remain basic, additionally the assessment of the ecological minimum helps to define design strategies for integrated flood protection, especially in situations where there is an opportunity for river rehabilitation.

No abstract

Land cover and landscape patterns dynamics over a 25 year period are analysed for a case study in Normandy. With the help of cartography, GIS and multivariate analysis, factors contributing to landscape structures and changes are studied. The results point out three main driving factors responsible for the landscape change: Agricultural practices which lead to intensification of some areas and abandonment of others, urbanisation which modifies the structure and organisation of the landscape, and finally, as factor of stability comes the conservation policies which check these changes in certain zones, Despite this last factor, the global resulting impacts are, up to now, the progressive disappearance of the organisation of the sites landscape. © 1997 Elsevier Science B.V.