Room for the River Final Report Sic
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Integrate, Consolidate and Disseminate European Flood Risk Management Research First CRUE ERA -Net Common Call Effectiveness and Efficiency of Non-structural Flood Risk Management Measures CRUE Research Report No I -6: Efficiency of non-structural flood mitigation measures: "room for the river" and "retaining water in the landscape" Prepared by the Joint Project Consortium consisting of Funded by Félix Francés (Joint project Co-ordinator), Rafael García-Bartual, Enrique Ortiz, Sergio Salazar Hydraulic and Hydrology Research Group José Luís Miralles Urban Planning Research Group Technical University of Valencia Günter Blöschl, Jürgen Komma, Christine Habereder Institute for Hydraulic and Water Resources Engineering Vienna University of Technology Axel Bronstert, Theresa Blume Institute of Geoecology, Chair for Hydrology and Climatology University of Potsdam CRUE Co-ordinator: John Goudie (Defra) Project Contract No: ERAC-CT-2004-515742 Project Website: www.crue-eranet.net © 2008 CRUE Funding Initiative on Flood Risk Management Research All rights reserved. DISCLAIMER Efficiency of non-structural flood mitigation measures: "room for the river" and "retaining water in the landscape" CRUE Research Report No I-6 This report was prepared with the support of the CRUE Funding Initiative on Flood Risk Management Research. While reasonable care has been taken in preparing this publication to ensure that information is appropriate and valid it have to be considered that the views, conclusions and recommendations expressed herein are those of the authors and most not necessarily endorse the views of the CRUE ERA-NET or the respective Funding bodies involved. The intent of the research reports is to provide relevant information and to stimulate discussion of those having an interest in flood risk management. The results and conclusions of all reports produced under the CRUE Funding Initiative on Flood Risk Management Research are made available to policy-makers and stakeholders at all levels, research funding bodies, universities, industries, practitioners, and the general public by way of the CRUE website ( http://www.crue-eranet.net ). This publication is copyright, but wide dissemination is encouraged. Requests and inquiries concerning reproduction and rights should be addressed to the CRUE Dissemination Manager on [email protected]. Researcher’s Contact Details Project partner #1 (Co-ordinator) ◄ Félix Francés Hydraulic and Hydrology Research Group Technical University of Valencia (ES) [email protected] Project partner #2 ◄ Günter Blöschl Institute for Hydraulic and Water Resources Engineering Vienna University of Technology (AT) [email protected] Project partner #3 ◄ Axel Bronstert Institute of Geoecology, Chair for Hydrology and Climatology University of Potsdam (DE) [email protected] In submitting this report, the researcher’s have agreed to CRUE publishing this material in its edited form, giving credits to all authors. CRUE Contact Details CRUE Co-ordinator Area 3D, Ergon House Horseferry Road London SW1P 2AL. United Kingdom Email: [email protected] Web: http://www.crue-eranet.net/ Published in November 2008 ERA-NET CRUE is funded by the ERA-NET Scheme under the 6th Framework Programme General Directorate for Research in the European Commission Contract number: ERAC-CT-2004-515742 CRUE FUNDING INITIATIVE ON FLOOD RISK MANAGEMENT RESEARCH ROOM FOR THE RIVER ERA-NET CRUE Funding Initiative on Flood Risk Management Research Risk Assessment and Risk Management: Effectiveness and Efficiency of Non-structural Flood Risk Management Measures Efficiency of non-structural flood mitigation measures: "room for the river" and "retaining water in the landscape" CRUE Research Report No I-6 Prepared by Funded by Félix Francés (Joint project Co-ordinator) Hydraulic and Hydrology Research Group Technical University of Valencia MEC (ES) Günter Blöschl Institute for Hydraulic and Water Resources Engineering Vienna University of Technology BMLFUW (AT) Axel Bronstert Institute of Geoecology, Chair for Hydrology and Climatology University of Potsdam BMBF (DE) III CRUE FUNDING INITIATIVE ON FLOOD RISK MANAGEMENT RESEARCH ROOM FOR THE RIVER 1st CRUE Funding Initiative on FRM research ERA-Net CRUE is a network of European government departments who directly fund flood risk management programmes and related research actions. In order to tackle the challenge of rising flood risk and to develop effective policies and risk management practices, policy-makers and key stakeholders need a strong evidence base. Evidence-based policy-making is the key to modern, forward-looking strategies for dealing with increasing flood risk. Trans-boundary and trans-national flood risk management issues are becoming more and more important, requiring in particular joint research and development initiatives. The creation and implementation of a European research area in flood risk management – as intended by the CRUE ERA-Net - is an important contribution to an improved trans-national perspective for flood-related research in Europe. Besides co-ordinating research between Member States, CRUE aims to contribute towards the presentation of research needs with its own trans-nationally based funding initiatives. Common trans-national research calls initiated by the partner countries are a principal activity within the CRUE ERA-Net which can be considered as specific actions to respond to current policy and development needs in Europe. With the launch of the first CRUE common call, a first step toward the integration of flood research in Europe was made. The topic “Risk Assessment and Risk Management: Effectiveness and Efficiency of Non-structural Flood Risk Management Measures” was selected by six of the CRUE partner countries through an intensive consultation process and is to a great extent based on developments in European flood risk management policy (e.g. EU Floods Directive). In particular, the call was designed to investigate and critically assess the effectiveness and efficiency of non-structural measures in comparison to structural measures and to identify barriers to implementation of these "soft" techniques. The call was an incentive to develop innovative methodological approaches. Moreover, it challenged researchers across Europe to integrate knowledge across different disciplines such as natural and social sciences, and engineering. Each of the seven successful joint projects within CRUE’s 1 st Funding Initiative for FRM research was designed to understand different national approaches to the use and appraisal of non-structural measures, explore what is successful, and what can be improved in terms of efficiency and effectiveness of such measures themselves. The research results presented in this report will provide policy-makers with a better understanding of how FRM as a part of integrated river basin management can deliver multiple benefits, for example reduced flood risk and improved environmental quality. I feel confident that the outcome of this research will be a valuable contribution to national policy development and the improvement of flood risk-related practice. John Goudie ERA-Net CRUE Co-ordinator, Defra, UK IV CRUE FUNDING INITIATIVE ON FLOOD RISK MANAGEMENT RESEARCH ROOM FOR THE RIVER Summary for Decision-Makers This report compiles the work done and the results obtained in this project. The project has focused on a comparison of the effectiveness of non-structural flood mitigation actions in three European catchments. In particular, measures based on the following concepts have been evaluated: a) “Retaining water in the landscape” by land use changes (afforestation and/or deforestation) and local retention measures of different numbers and sizes: micro-ponds (around 1,000 m 3 and no outlet structure), micro-reservoirs (in the order of 10,000-70,000 m 3), small dams (less than 1,000,000 m³) and one single dam (more than 1,000,000 m³), and b) “Room for the river”, which are measures within the floodplain involving natural and forced (polders) flooding areas. The effectiveness of each measure has been estimated in terms of the reduction of hazard magnitude and risk. The study of three catchments located in Spain (Poyo, 380 km 2), Austria (Kamp, 1500 km²) and Germany (Iller, 954 km 2), with three different climates (semi-arid, sub-alpine and alpine), has permitted to cover a wide spectrum of flood processes that can be expected in Europe. Main project results Physical processes and modelling 1600 dry initial cond. 1400 wet initial cond. Runoff generation depends on precipitation 1200 magnitude, but can be highly dependent on processes not usually considered in flood 1000 studies: soil moisture initial conditions, and 800 temporal and spatial variability of the storm. 600 As can be seen in Fig. 1 for the Poyo catchment, storms of 24 hr precipitation Peak runoff (m³/s) 400 around 100 years return period, can produce 200 3 peak floods from 200 to 1200 m /s. The 0 internal storm variability in the Poyo 1 10 100 1000 10000 catchment is due to the torrenciality of the 24h max precipitation return period (yrs) Figure 1. Influence of the temporal and spatial variability of Mediterranean climate. precipitation (100 synthetic storms) and initial soil moisture conditions (two initial states) for the present conditions in the Poyo In the Iller catchment, the poor observation of catchment. the actual altitudinal gradient of precipitation was a major challenge with respect to hydrological modelling. With the proper input