Improving flood risk analysis for effectively supporting the implementation of flood risk management plans: The case study of “Serio” Valley

Abstract The EU Flood Directive 2007/60 requires the assessment and delineation of flood risk maps. The latter should provide the required knowledge for the development of flood risk management plans (FRMPs), that should deal with all features of risk management: e.g. preparation, protection and prevention, comprising also the phase of the flood forecasting and warning systems, in addition to the emergency management. The risk maps, delineated through the expert-drive qualitative (EDQ) approach currently adopted in several European countries, such as Italy, fail to represent the information base that needed by stakeholders for selecting the suitable objectives and designing the appropriate mitigation actions for flood risk management. In the EDQ approach, the flood hazard and the potential damage degree maps are combined by means of a matrix to obtain a qualitative flood risk map. However, the performance of the risk matrix is not usually rigorous validated and, therefore, presents limits, such as subjective and not careful explained interpretation of rating and poor resolution, (due to range compression), that can produce errors in comparative ranking of risk areas. In this context, this paper proposes the FloodRisk approach that aims to improve the efficacy of flood risk map overcoming the limits of EDQ approach in supplying the knowledge base that allow to analyze costs and benefits of potential mitigation measures. However, the proposed approach is also able to involve the citizens in the flood management process, enhancing their awareness. An application of FloodRisk procedure is showed on a pilot case in “Serio” Valley, (North Italy), and its strengths and limits, in terms of additional efforts required in its application compared with EDQ procedure, have been discussed focusing on the efficacy of the outcomes provided for the fulfillment of FRMPs. The results have demonstrated the ability of FloodRisk, respect to EDQ approach, to distinguish successfully different levels of vulnerability of exposure elements, thanks to the use of asset value and depth-damage curves, that allows a suitably evaluation of the effectiveness of risk mitigation strategies. In this light, a successfully application of a cost-benefit analysis of FloodRisk approach on a portfolio of alternative mitigation actions, (i.e. structural and non-structural measurements), has been demonstrated on the proposed study case. However, FloodRisk requires additional information, e.g. water depths assessment and assets values, and it needs a proper analysis and communication of the uncertainty in its results. Although they still exist limitations that impede, at present, the FloodRisk application without an adequate understanding and a critical consideration of the hazard, exposure and vulnerability characteristics of the study area, considerations are supplied on how the utilization of this approach can be maximized in the light of the next flood risk maps revision due by December 2019.

[1]  Annegret H. Thieken,et al.  Review article: assessing the costs of natural hazards - state of the art and knowledge gaps , 2013 .

[2]  Guido Nigrelli,et al.  Application of a model to the evaluation of flood damage , 2009, GeoInformatica.

[3]  Dagmar Haase,et al.  Exploring multicriteria flood vulnerability by integrating economic, social and ecological dimensions of flood risk and coping capacity: from a starting point view towards an end point view of vulnerability , 2011 .

[4]  H. Moel,et al.  Flood maps in Europe – methods, availability and use , 2009 .

[5]  David Ingle Smith Actual and potential flood damage: a case study for urban Lismore, NSW, Australia , 1981 .

[6]  Bruno Merz,et al.  Review article "Assessment of economic flood damage" , 2010 .

[7]  Dagmar Haase,et al.  A multicriteria approach for flood risk mapping exemplified at the Mulde river, Germany , 2009 .

[8]  Jan Adamowski,et al.  Modelling large floating bodies in urban area flash-floods via a Smoothed Particle Hydrodynamics model , 2016 .

[9]  Philippe De Maeyer,et al.  Development of a flood risk model and applications in the management of hydrographical catchments , 2005 .

[10]  Ignacio Escuder-Bueno,et al.  A quantitative flood risk analysis methodology for urban areas with integration of social research data , 2012 .

[11]  Ignacio Escuder-Bueno,et al.  The suitability of risk reduction indicators to inform dam safety management , 2016 .

[12]  C. D. Gamper,et al.  A conceptual approach to the use of Cost Benefit and Multi Criteria Analysis in natural hazard management , 2006 .

[13]  Daniela Molinari,et al.  Implementing the European “Floods Directive”: the Case of the Po River Basin , 2016, Water Resources Management.

[14]  Salvatore Manfreda,et al.  MY SIRR: Minimalist agro-hYdrological model for Sustainable IRRigation management - Soil moisture and crop dynamics , 2017, SoftwareX.

[15]  Bjørn Vidar Vangelsten,et al.  Assessing the risk posed by natural hazards to infrastructures , 2015 .

[16]  K. M. de Bruijn,et al.  Uncertainty in flood damage estimates and its potential effect on investment decisions , 2015 .

[17]  Volker Meyer,et al.  Integrated urban flood risk assessment – adapting a multicriteria approach to a city , 2009 .

[18]  Jan Adamowski,et al.  READY: a web-based geographical information system for enhanced flood resilience through raising awareness in citizens , 2015 .

[19]  B. Merz,et al.  Development and evaluation of FLEMOps - a new Flood Loss Estimation MOdel for the private sector , 2008 .

[20]  Raffaele Albano,et al.  THE LASER SCAN DATA AS A KEY ELEMENT IN THE HYDRAULIC FLOOD MODELLING IN URBAN AREAS , 2013 .

[21]  R. Brouwer,et al.  Integrated ecological, economic and social impact assessment of alternative flood control policies in the Netherlands , 2004 .

[22]  Jan Adamowski,et al.  A GIS-based model to estimate flood consequences and the degree of accessibility and operability of strategic emergency response structures in urban areas , 2014 .

[23]  Volker Meyer,et al.  Recommendations for the user-specific enhancement of flood maps , 2012 .

[24]  Zahra Kalantari,et al.  Predicting and communicating flood risk of transport infrastructure based on watershed characteristics. , 2016, Journal of environmental management.

[25]  Raffaele Albano,et al.  A Smoothed Particle Hydrodynamics model for 3D solid body transport in free surface flows , 2015 .

[26]  Francesca Carisi,et al.  Evolution of flood risk over large areas: Quantitative assessment for the Po river , 2015 .

[27]  P. Lal,et al.  Evaluation of the role of risk perception in stakeholder engagement to prevent lead exposure in an urban setting. , 2016, Journal of environmental management.

[28]  Jan Adamowski,et al.  Collaborative Strategies for Sustainable EU Flood Risk Management: FOSS and Geospatial Tools - Challenges and Opportunities for Operative Risk Analysis , 2015, ISPRS Int. J. Geo Inf..

[29]  George Tsakiris,et al.  Flood risk assessment: concepts, modelling, applications , 2014 .

[30]  Lukas H. Meyer,et al.  Summary for Policymakers , 2022, The Ocean and Cryosphere in a Changing Climate.

[31]  Fausto Guzzetti,et al.  Societal landslide and flood risk in Italy. , 2010 .

[32]  A. R. Scorzini,et al.  Flood damage curves: new insights from the 2010 flood in Veneto, Italy , 2017 .

[33]  Hans de Moel,et al.  Uncertainty and sensitivity of flood risk calculations for a dike ring in the south of the Netherlands. , 2014, The Science of the total environment.

[34]  Jeroen C. J. H. Aerts,et al.  Uncertainty and sensitivity analysis of coastal flood damage estimates in the west of the Netherlands , 2012 .

[35]  J. Chatterton,et al.  The Benefits of Flood and Coastal Risk Management: A Handbook of Assessment Techniques , 2005 .

[36]  P M Haygarth,et al.  A cloud based tool for knowledge exchange on local scale flood risk. , 2015, Journal of environmental management.

[37]  S. Perales-Momparler,et al.  Enhancing local action planning through quantitative flood risk analysis: a case study in Spain , 2016 .

[38]  G. Di Baldassarre,et al.  Towards understanding the dynamic behaviour of floodplains as human-water systems , 2013 .

[39]  Jeroen C. J. H. Aerts,et al.  Comparative flood damage model assessment: towards a European approach , 2012 .

[40]  Louis Anthony CoxJr Limitations of Risk Assessment Using Risk Matrices , 2009 .

[41]  L. Feyen,et al.  Global warming increases the frequency of river floods in Europe , 2015 .