United States-Italy Research Workshop on

HYDROMETEOROLOGY, IMPACTS, AND MANAGEMENT
OF EXTREME FLOODS

Summary, Conclusions, and Recommendations

The United States and some European countries have recently experienced the occurrence and the impacts and consequences of extreme floods. A US-Italy Research Workshop was organized where a selected group of flood specialists discussed and exchanged experiences in relation to recent catastrophic flood events. The research workshop was held at Perugia, Italy. The objectives of the Workshop were: (a)To present and document the state of the art on the hydroclimatology, impacts, and management of extraordinary floods. (b) To organize and discuss potential research topics on the hydrometeorology, impacts, and management of extraordinary floods, especially those of potential collaboration between researchers in the U.S. and Italy. (c)To contrast and compare structural and non-structural approaches to floods, especially in terms of underlying preventive policies, risk and uncertainty management of catastrophic events, and mobilization of resources and institutions in case of extreme hydrologic events. (d) To disseminate the Research Workshop findings to the U.S. and European professionals and agencies interested on flood hazards and to inform the general public in both increased awareness and participation with regard to managing floods.

The referred Research Workshop was attended by 41 experts in the field of extreme floods from the United States (14), Italy (17), Spain (2), Belgium (1), United Kingdom (2), Germany (1), Greece (2), and The Netherlands (2). The workshop participants prepared written material on pre-determined subjects related to the theme of the workshop which were presented during plenary sessions of the meeting and served as the basis for discussions. Additional round table sessions in smaller groups were held to discuss the definition, importance, justification, and classification of potential research areas and topics which were felt are needed to cope with extreme floods.

Coping with extreme floods requires decision making at many levels, from the general policy of land management and urban development to the specifics of engineering design, including the implementation of technically sound warning systems, and the evaluation and implementation of social response. At the present time society is coping with extreme floods presumably using the best resources and knowledge currently available and applying the best technology that is economically and financially feasible. Nevertheless, it is imperative to improve our knowledge in order to build better decision tools and support systems which can take into account, the many complexities of the underlying physical and statistical processes involved, and the many complexities and interactions of social and institutional systems. The US-Italy Research Workshop on the Hydrometeorology, Impacts, and Management of Extreme Floods has been an effort in that direction.

The research topics which have emerged from the referred workshop have been categorized into nine research areas, namely: (A) Remote Sensing, Data, Modeling and Prediction, (B) Scales and Variability, (C) Systematization and Interaction of Structural and Non-Structural Measures, (D) Environmentally Sensitive and Flexible Approach to Design and Maintenance of Flood Control Measures, (E) Constraints Influence in Flood Protection and Vulnerability, (F) Risk Dynamics and Decision Making, (G) Education, Communication, and Knowledge Transfer, (H) Institutional and Organizational Change, and (I) Characterization of Occurrence of Extreme Floods. The list of the research topics under each category are shown bellow. Further definition of potential research topics can be found in the individual papers included in Parts I, II, III, and IV of the Workshop Proceedings.

The recommended research areas and topics resulting from the Research Workshop are:

A. Remote Sensing, Data, and Modeling and Prediction

A1. Improvements in process physics and measurements.

A2. Development of real time rainfall estimation and forecasting by integrating remote sensing and mesoscale atmospheric models.

A3. Integrated real time rainfall and flow prediction with distributed approaches.

A4. Uncertainty and variability in prediction at various scales and conditions.

A5. Estimation of hydrological fluxes and states from on-site and remote sensors using (a) statistical approaches and (b) process model approaches.

A6. Uniform evaluation techniques for consistent assessment of flood losses, and disaster relief and mitigation.

B. Scales and Variability

B1. Storm and geomorphologic scales interactions for the production of extreme floods.

B2. Scales of forcing and feedback between precipitation and soil moisture.

B3. Scales and predictability of extreme rainfall and floods.

B4. Physical causes of rainfall and flow space and time variability.

C. Systematization and Interaction of Structural and Non-Structural Measures

C1. Regional studies of impacts on socio-economic and environmental systems of technology for managing extreme floods.

C2. Hydraulic and hydrologic interactions and impacts of structural and non-structural methods. Hydraulic design of the floodplain in a global perspective.

C3. Distributed small scale control measures.

C4. Interactions of river and geomorphological dynamics with engineering works.

C5. Cumulative impacts of major floods on ecosystems.

C6. Regional studies of impacts on social systems of managing technology for flood control.

C7. Flood management integration with other hazards, environmental management, and management for sustainable development.

C8. Feasibility effectiveness of replacing engineered systems with natural systems.

D. Environmentally Sensitive and Flexible Approach to Design and Maintenance of Flood Control Measures

D1. Benefit-cost analysis of using wetlands as non-structural flood mitigation measure.

D2. Geomorphological, ecological, and aesthetical aspects or river training and mitigation measures.

D3. Geomorphologically effective landscape design.

D4. Feasibility and effectiveness of river restoration.

D5. Integration of engineering design within both global and sustainable river and catchment system.

D6. Enviromentally sound design methods for river engineering structures (levees, flood pools, floodways, etc.).

D7. Robustness and adaptability of flood control measures in a changing environment.

E. Constraints Influence in Flood Protection and Vulnerability

E1. Hillslope processes (karst, arid, and deserted catchments).

E2. Identification of channel and river network constraints from geomorphological and anthropogenic points of view. Channel capacity identification.

E3. Interactions of riverine floods with urban drainage systems.

E4. Constraints related to land subsidence and sea level transients (coastal tides and surges).

E5. Inverse problem in flood hydrology.

E6. Implications of constraints to decision making.

F. Risk Dynamics and Decision Making

F1. Reliability of flood prediction and forecasting for structural and non-structural systems.

F2. Design criteria for the structural systems based on risk and reliability engineering approaches.

F3. Flood risk modification by large dams.

F4. Risk perspective in a changing environment.

F5. Relationships between protection level and willingness to invest.

F6. Threshold of social risk tolerance.

F7. Quantification of non-monetary costs and benefits of extreme floods.

F8. Dynamics of the effects of increasing concentration of wealth in floodplains.

G. Education, Communication, and Knowledge Transfer

G1. Adoption, maintenance, constraints, and incentives for local warning systems.

G2. Enhanced public education and outreach by scientists and engineers.

H. Institutional and Organizational Change

H1. Integrate flood mitigation into river basin management.

H2. Improved procedures for information transfer between scientists and decision makers.

H3. Develop institutional response for transboundary water systems.

H4. Government actions and their influence on floodplain occupancy; impact of insurance and relief.

H5. International or interregional rivers: determination of the role of the various governmental levels in floodplain management.

H6. Enhancement of stakeholder solidarity within a river basin.

H7. Post-audits of existing and planned non-structural measures.

I. Characterization of Occurrence of Extreme Floods

I1. Estimation of occurrence probability using historical and paleo data.

I2. Effects of climate trends and variability.

I3. Effects of land changes and variability.

I4. Estimation in ungaged watersheds.

I5. Interaction of river regimes and extreme flood magnitude.

I6. ENSO influences.