Floods and related Hydrogeological Risks

 

This self-tuition workshop was organised from the 23rd to the 25th of May 1996 by the Italian National Group for Hydrogeological Disaster Prevention and the Italian National Research Council – Department of Civil Protection (Prof Ing. Lucto Ubertini, Presidente del Gruppo Nazionale Difesa Catastrofi Idrogeologiche, Dr. Marta La Ponzina, Dir. Superiore Dipartmento della Protezione Civile, Coordinatore Servizio Formazione, Hospitality Service, Via S. Salvatore in Lauro 6, I – 00100 Roma, Italy).

 

Conclusions

In the results from the workshop, it was recognised that there are similarities and differences in the national administrative structures and legal frameworks as well as problems related to the multiplicity of actors responsible. This underlines the need for co-ordination. Any prevention strategy for natural events should be elaborated only after an analysis and assessment of the risks. The results of the assessment are often collected in a risk map. There was recognition of the growing significance of disasters in the hydro-geological field which are meant to be due to climatic changes but also to the anthropomorphic factor.

It was concluded that a certain amount of interest has been dedicated to environmental engineering measures with the aim of retaining water and promoting its absorption by the soil. Further, there was agreement on the need for evaluating the inter-action between different types of risks and for involving all responsible for prevention and preparedness in the risk assessment. The measures undertaken in respect to prevention and preparedness or response should be integrated with each other and based on a cost-benefit analysis. An intermediate report on a comparative analysis of crisis management during the 1993-1995 floods in Western Europe was presented.

The workshop suggested that work should be started on the following three areas:

• Administrative and legal procedures and identification of appropriate tools for the management of floods in metropolitan areas.
• Resolving problems of risk-prone area mapping with special consideration to mountainous and arid regions.
• Co-ordination and organisation of crisis units and real-time forecasting systems.

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1. Administrative and legal procedures and identification of appropriate tools for the management of floods in metropolitan areas.

Objectives

• Analyse past experiences (lessons learned in Greece, Italy, France, Spain, Portugal and other countries)
• Promote application of the latest state-of-the-art procedures for the analysis of the phenomena of interest
• Evaluate the specificity of organisational problems induced by factors such as high population density and the areal extension of the urbanised area, taking into account - among the others - security of utility networks (lifelines), secondary damages induced by the interruption of economic/industrial activities, traffic jam problems, etc.
• Compare different national behaviours, and possibly define the guidelines for a proposal of development of European Directive aimed at avoiding or minimising superposition and conflicts of competence

Expected outcome

• Preparation of a «white book» containing :
  • an analysis of past experiences in the different Member countries with respect to the following : types of floods occurred; systems and levels of defence against floods; forecasting and alert systems; emergency management
  • the identification of typical flood situations,
  • the definition of guidelines for the prevention and management of the above identified "typical" flood crisis in metropolitan areas.  This shall include details on local conditions, administrative and legal situations, and a comparative analysis thereof
• creation of a "decision support system for crisis management", adaptable to local conditions, that should be able to forecast and analyse flood risk situations, and suggest short-term (emergency) action lines that take into account the specificity of the situation
• implementation of the above-mentioned decision support system for crisis management in representative case studies in different countries.

2. Resolving problems of risk-prone area mapping with special consideration to mountainous and arid regions.

Objectives

• The objective of the proposed project is to conduct an inventory and comparison of presently used methods in each country, and to perform a comparative implementation and application of different methods to selected significant areas, in view of the joint definition and presentation of common guidelines.
• Key issues to be considered are:
  • Flood hazard estimation, consisting of an inventory of past disastrous rainfall; regional statistical analysis of extreme rainfall; evaluation of infiltration capacity, considering soil lithology, surface type, morphology (relief slopes), land uses (forestation, cultivation, urbanisation, etc...); regional flood frequency analysis; sediment load prediction (mudflow, debris flow, landslide near fluvial reaches); definition of T-year flooding areas by fixed-bed stationary flow hydraulic models, or for critical fluvial reaches (declining water velocity): mathematical models of movable bed evolution.
  • Prevention, for which the importance of a non-structural approach, the regulation of land use in the areas susceptible to riverine flooding, and emergency management plans must be considered.

Expected outcome

• Outcomes of the project will be:
  • high hazard climatic zoning;
  • geomorphological (infiltration) zoning;
  • flood distribution parameter zoning, including mean annual flood, growth factors (with T-return period);
  • debris flow formation;
  • mud flow formation;
  • landslides triggering, including massive sediment supply zoning;
  • floodplain mapping, including critical points (bridges, etc...);
  • development of guidelines to carry out the above listed tasks;
  • a pilot project for a selected basin to be initiated in each country.

3. Co-ordination and organisation of crisis units and real-time forecasting systems.

Objectives

• The first objective of the proposed project should be the comparison of the different scenaria with respect to which emergency planning is designed, conducted by analysing experiences in different countries, possibly through reconsideration's and critical examination of past performances in real life flooding catastrophes.
• The second objective of the proposed project should be the definition, based upon the comparative analysis of the scenaria, of possible co-operative actions aimed at a better use of state-of-the-art technology, in order to minimise as possible the uncertainty of predictions and increase the leading time.
• The similarity of the possible scenaria regarding the management of civil protection action in the Mediterranean area of southern Europe was evidentiated during the workshop: in fact, various European Regions with Mediterranean climate face the risk of sudden and severe floods -flash floods-, that are difficult to predict without a preventive mapping of areas exposed to the risk and proper meteorological modelling, real-time data collection and adequate hydrological modelling.  During the workshop significant case studies of hydrometeorological monitoring applications to civil protection emergency management had been presented.
• Currently, the use of multisensor monitoring systems is expanding in conjunction with atmospheric and hydrological modelling: sensors flying on board of geosyncronous and polar satellites, meteoradars and networks of ground based hydrometeorological sensors are commonly in use.
• Furthermore, agreements and cooperation between weather forecasting bureaux are being implemented between neighbouring countries with the aim of improving the overall capability to forecast and ground-validate modelling predictions.
• This kind of co-operative actions ought to be better focused on the emerging demand arising from civil protection needs, including emergency planning scenaria as prepared and comparatively discussed between neighbouring countries.

Expected outcome

• The purpose of the second part of the project should be to involve responsible officials in charge of technical agencies, in order to exchange experiences and possibly agree on common procedures for data exchange in real time.
• The proposed actions should take into account ongoing projects, namely the Interreg II call for proposals which is due next September.

last update: 09/08/2007

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