Liu Xi-lin

Site-specific vulnerability assessment for debris flows: Two case studies

Here the vulnerability is defined as the potential total maximum losses due to a debris flow damaging event for a specific debris flow fan. The vulnerability is classified into property vulnerability and population vulnerability. Assessment indexes include the assets of buildings, traffic facilities, lifeline works, personal properties, and land resources for property vulnerability; age, education, and wealth of the inhabitants, natural population growth rate, and population density for population vulnerability. The vulnerability is expressed as the sum of the transformed values of the losses of property and population. Two study cases with post-fact damages by historic debris flow events in Sichuan of SW China are presented.

Gully-specific debris flow hazard assessment in China

Techniques of gully-specific debris flow hazard assessment developed in four periods since the end of the 1980s have been discussed in the present paper. The improvement for the empirical assessment method is the sectionalized function transformation for the factor value, rather than the classified logical transformation. The theoretical equation of the gully-specific debris flow hazard is expressed as the definite integral of an exponential function and its numerical solution is expressed by the Poisson Limit Equation. Current methods for assessment of debris flow hazard in China are still valid and practical. The further work should be put on the study of the reliability (or uncertainty) of the techniques. For the future, we should give a high priority to the relationship between debris flow magnitude and its frequency of occurrence, make more developments of prediction model on debris flow magnitude, so as to finally reach the goal of assessing the hazard of debris flow by theoretical model, and realize both actuality assessment and prediction appraisal of debris flow.

Disasters and regional risks of debris flow in Zhaotong Prefecture, Yunnan Province, China

Zhaotong Prefecture has the area of 22,434km2, where there are more than 330 debris flow ravines, with the average spatial density of 14.7 spots per 1,000km2. According to the method of evaluation on the regional risk of debris flow, this study has come to the following conclusions: Qiaojia County-risk grade V; Yongshan, Yanjin, Ludian, Daguan, Weixin and Zhenxiong counties-risk grade III; Yiliang, Suijiang-Shuifu and Zhaotong City-risk grade II. Compared with the field investigation, the result is satisfied.

Recent developments in debris flow research in Italy

Debris flows play an important role among natural hazards in mountainous areas of Italy. This paper provides an overview on the recent research on debris flows conducted in Italy, taking into account both hydraulic and geomorphological studies. Moreover, the most encouraging research perspectives in this field are briefly presented, such as the monitoring of debris flow in instrumented basins and the geotechnical analysis of the processes leading to debris flow initiation. Finally, two study cases are reported, with the aim of outlining the main characteristics of these phenomena and consequent risk conditions in representative sites in the Italian mountains.Debris flows play an important role among natural hazards in mountainous areas of Italy. This paper provides an overview on the recent research on debris flows conducted in Italy, taking into account both hydraulic and geomorphological studies. Moreover, the most encouraging research perspectives in this field are briefly presented, such as the monitoring of debris flow in instrumented basins and the geotechnical analysis of the processes leading to debris flow initiation. Finally, two study cases are reported, with the aim of outlining the main characteristics of these phenomena and consequent risk conditions in representative sites in the Italian mountains.

The catastrophe forecast of the annual sidement transport by debris flow in Jiangjia Gully, Yunnan Province, China

On the basis of the observational data on the annual sediment transport by debris flow in recent 8 years, appling the catastrophe forecast method of Grey System Theory, this study has established the catastrophe model of the annual sediment transport by debris flow in Jiangjia Gully. It has forecasted the next potential catastrophic year in which the annual sediment transport will be over the catastrophic threshold 2 million m3. Furthermore, it has introduced the “equal dimension-new information model”, which makes the forecast be done continuously.