H.G. Wind

Analysis of flood damages from the 1993 and 1995 Meuse Floods

This paper addresses uncertainties pertaining to damage assessments made for the floodings of the Meuse River in 1993 and 1995. The analysis is based on flood damage data that were collected by damage experts and consist of large sample sizes within each municipality. The most interesting aspect of these two floods is that although the volume of flooding and the inundated area were comparable in order of magnitude, the flood damage estimates in 1995 were 35% lower than in 1993. We conclude that part of the reduction in flood damage during the 1995 flood was due to a reduction in the damage to household goods. This may be explained by a marginal increase in flood warning time and experiences gained from the flood of 1993. As flood damage assessments are the cornerstone in the evaluation of flood damage mitigation schemes, empirical data of previous floods should be used to improve the foundations of the methods to assess flood damages.

Modeling land-use change in a decision-support system for coastal-zone management

RaMCo is a prototype version of a decision-support system for coastal-zone management. The model is based on the findings of a multidisiciplinary research program, conducted in Southwest Sulawesi, Indonesia. Different management strategies can be compared on the basis of the short- and long-term consequences. Land-use change has been included in RaMCo in view of the impacts of land-based human activities on the marine environment. The key aspect of the model is a combination of the temporal dynamics of land-use change on the regional (macro-level) scale and spatial dynamics on the local (micro-level) scale. Constrained cellular automata are used to integrate both scale levels. The state changes of the cells depend on the consistency with the macro-scale model, local geographical conditions, and interaction with neighboring cells. In this paper, we discuss the underlying theoretical assumptions of the macro-scale and micro-scale models, some characteristic results for land-use change in the study area, and the validation problem.

Design and application of decision-support systems for integrated water management: lessons to be learnt

During the annual meeting of the European Geophysical Society in 2001 a special session was organized around the design and application of decision-support systems for integrated water management. There is a growing realization among policy makers and scientists that ecological, social-economic and physical aspects of water management cannot be dealt with separately. This has lead to a growing number of tools to support the decision-making process in water management dealing with the water system in an integrated way. Example applications are flood forecasting, multi-reservoir operation, urban waste-water management, and integrated river-basin management. The design, which is ideally based on intensive communication between scientists, system designers and envisaged end users, is often a tedious process. In general, it can be concluded that, in despite of the effort invested in process modeling, data collection, and the growing experience in developing integrated system models, practical application of decision-support systems still runs behind the availability of these tools.

Application of fuzzy sets and cognitive maps to incorporate social science scenarios in integrated assessment models

Decision–support systems in the field of integrated water management could benefit considerably from social science knowledge, as many environmental changes are human-induced. Unfortunately the adequate incorporation of qualitative social science concepts in a quantitative modeling framework is not straightforward. The applicability of fuzzy set theory and fuzzy cognitive maps for the integration of qualitative scenarios in a decision–support system was examined for the urbanization of the coastal city of Ujung Pandang, Indonesia. The results indicate that both techniques are useful tools for the design of integrated models based on a combination of concepts from the natural and social sciences.

Improving Control In Water Management. Meeting conditions for control with the ISI-approach

Water management steers a middle course between control and chaos. The concept of control in water management is the topic of this paper. Conditions for control in water management are: aconsistent policy, gaining support and an adequate informationsupply. It is demonstrated that the balance between these three conditions of control depends on the type of water managementconsidered. In this paper four different types of water management are distinguished based on the conditions for control.The concept presented in this paper is validated on basis of three case studies. The paper concludes with a presentation of an approach which is interactive and aims at an integral and sustainable development.

Multiobjective decision-making in integrated water management

Traditionally, decision-making by water authorities in the Netherlands is largely based on intuition. Their tasks were, after all, relatively few and straight-forward. The growing number of tasks, together with the new integrated approach on water management issues, however, induces water authorities to rationalise their decision process. In order to choose the most effective water management measures, the external effects of these measures need to be taken into account. Therefore, methods have been developed to incorporate these effects in the decision-making phase. Using analytical evaluation methods, the effects of various measures on the water system (physical and chemical quality, ecology and quantity) can be taken into consideration. In this manner a more cognitive way of choosing between alternative measures can be obtained. This paper describes an application of such a decision method on a river basin scale. Main topics, in this paper, are the extent to which uncertainties (in technical information and deficiencies in the techniques applied) limit the usefulness of these methods, and also the question whether these techniques can really be used to select measures that give maximum environmental benefit for minimum cost. It is shown that the influence of these restrictions on the validity of the outcome of the decision methods can be profound. Using these results, improvement of the methods can be realised.

Assessment of flood damages and benefits of remedial actions: “What are the weak links?”; with application to the Loire

Flood damage models are used to determine the impact of measures to reduce damage due to river flooding. Such models are characterized by uncertainty. This uncertainty may affect the decisions made on the basis of the model outcomes. To reduce uncertainty effectively, the most important sources of uncertainty must be found. Uncertainty analysis serves this purpose. By way of a questionnaire experts were asked about their judgment of the significance of uncertainty sources in flood damage assessment. The results of this questionnaire are compared to an uncertainty analysis by Monte Carlo Simulation, which Torterotot (1993) applied to the French model CIFLUPEDE. The paper concludes that the role of uncertainty in flood damage assessment is highly significant and cannot be neglected. Both the experts and the analysis on the flood damage assessment model indicate the hydrologic relations ‘frequence of occurrence — river discharge — river water level’ and the damage estimates as the most important uncertainty sources. For embanked rivers dike breach is the most significant uncertainty source. A question which appears is, taking into account these uncertainties, to what level of precision can flood damage assessment models predict the expected annual flood damage and the costs and revenues of flood alleviation measures? It is of importance to explore the boundaries of flood damage modeling and to try to find ways to move these boundaries. The uncertainty analysis presented in this paper can be seen as one more step on the way to this goal.

Towards a program of measures in the context of the European Water framework Directive

In the European Water Framework Directive [1] the concepts underlying the management of the EU-waters are described. Attention is paid to many aspects such as the administration, emissions, objectives and monitoring. For each river basin these topics should be condensed in a river basin plan. The contents of such a river basin plan are described in Appendix VII of the EU Water Framework Directive and contain 11 topics. One of the topics is the plan of measures. In this paper the coherence between the topics of a river basin plan and the plan of measures is explored and is applied to the Elbe River in Germany. Towards river basin management plans for all European rivers In 2000 the European Commission accepted the European Water Framework Directive [1]. This directive formulates that plans for River Basin Management should be developed for each of the European Rivers. For the contents of these plans 11 requirements are formulated. The first part of the plan should be finished by 2004 while the plans should be operational by 2012. The requirements for a River Basin Management Plan, mentioned in the next paragraph, serve a number of administrative, legal and technical purposes. Each of these purposes requires different data and information. In the present paper the coherence between the 11 requirements is investigated from the point of view of one of the EU requirements “a summaty of the programme of measures, including how the (environmental) objectives must be achieved”. To that extent first the 11 requirements will be subdivided into 9 requirements which have a technical nature and 2 requirements which serve the consultation

FLOOD AND EROSION CONTROL IN THE CONTEXT OF SEA-LEVEL RISE

A special reflecting wall 12 m long and 2.1 m high was built off the beach at Reggio Calabria, and 30 wave gauges were assembled before the wall and were connected to an electronic station on land. It was possible to observe the reflection of wind waves generated by a very stable wind over a fetch of 10 Km. The experiment aimed to verify the general closed solution for the wave group mechanics (Boccotti, 1988, 1989), for the special case of the wave reflection.Significant features on Wadden Sea wave climate are evaluated in respect of the state of the art. Main emphasis was laid on an analysis of the governing boundary conditions of local wave climate in island sheltered Wadden Sea areas with extensions being sufficient for local wind wave growth. Explanatory for significant wave heights a reliable parametrization of local wave climate has been evaluated by using generally available data of water level and wind measurements.