The Course was held from June 18 to June 21, 1996 at the Institute for Hydrogeological Protection in central Italy, Perugia.

Debris flows are common in mountainous terrain worldwide and pose a serious hazard to communities and structures built on fans. Debris-flow hazards are serious in both the western United States and in the mountains of Italy. Expansion of urban areas continues to heighten the need for improved abilities in the prediction and mitigation of damage caused by debris flows. Understanding of the debris-flow hazard must entail a quantitative, process-based understanding of: (1) debris-flow initiation mechanisms, (2) the flow mechanics or rheology, and (3) the depositional behavior of debris flows on fans -- where debris flows and man most often overlap. The course is structured around these three aspects of the debris-flow hazards problem. Focus is on processes and quantitative analysis. (1) Initiation. Processes and mechanisms of debris-flow initiation are reviewed. Geologic (soil grain size distribution, soil strength, soil thickness), climatic (short-term rain fall intensity, antecedent moisture, root strength), and physiographic (slope) controls are discussed. Special considerations in volcanic terrains are considered and problems for future research outlined. (2) Rheology. Current understanding (and mis-understanding) of debris-flow rheology is discussed, emphasizing the importance of strain rate and minor differences in debris grain-size distribution. Constitutive relations suitable for use in hydrodynamic routing models, and applicable to mud-rich debris flows, are developed. Needs for future research are outlined. (3) Hazards on fans. Runout and deposition of debris flows on fans are discussed. Field examples from the western United States, Japan, and China are used to draw a general understanding of the interactions of debris flows and fluvial processes on fans. Both modeling and remote sensing approaches to the interpretation of fan hazard are presented.

Debris-flow initiation
- course introduction; description/definitions/review
- processes and analysis
- volcanic debris flows; outstanding problems

Debris-flow rheology
- physics of debris flow
- constitutive models
- lab and field data and analysis -- mud-rich and boulder-rich flows

Debris-flow routing
- review, problems and approaches
- numerical simulation, resistance equations

Debris-flow fans: morphology and hazards
- occurrence and recognition of debris-flow fans
- interaction of debris-flows and streams on fans, rheological control
- field and remote sensing recognition of hazard; analysis

Review of outstanding problems and discussion