Coupling a 3D patch model and a rockfall module to assess rockfall protection in mountain forests

Many forests in the Alps are acknowledged for protecting objects, such as (rail) roads, against rockfall. However, there is a lack of knowledge on efficient silvicultural strategies and interventions to maintain these forests at optimal protection level. Therefore, assessment tools are required that quantify the rockfall protection effect of forest stands over time, and thereby provide the ability to evaluate the necessity and effect of management interventions. This paper introduces such a tool that consists of a 3D rockfall module embedded in the patch based forest simulator PICUS. The latter is extended for this study with a new regeneration module. In a series of experiments the new combined simulation tool is evaluated with regard to parameter sensitivity, model intercomparison experiments with recently proposed algorithms from the literature, and the ability to respond realistically to different management regimes in rockfall protection forests. Results confirm the potential of the new tool for realistic simulation of rockfall activity in heterogeneous mountain forests, but point at the urgent need to improve the knowledge base on the interaction of understory and rockfall activity. Further work will focus on model validation against empirical rockfall data, and include reduced tree vitality due to damage from boulder collisions as well as the explicit consideration of downed dead wood.     

Combining HAZOP with dynamic simulation—Applications for safety education

A quantitative variation of the hazard and operability analysis (HAZOP) procedure is demonstrated. The process is divided into sections and dynamic models of the separate sections are prepared. Those models are used in the framework of the HAZOP procedure to determine the magnitude of the deviations from normal operation conditions that may lead to serious accidents and to test design modification to improve the safety characteristic of the process. A process involving an exothermic reaction conducted in a semi-batch reactor is used to demonstrate the advantages of the proposed procedure and its application for safety education and operator training. The programs used for simulating the reactor are available at: ftp://ftp.bgu.ac.il/shacham/OctanoneProd/.

It is shown that the use of those programs can enhance considerably the safety education by providing tools for systematic screening of process deviation associated with possible hazardous events, determining the threshold values that may lead to such events and enabling the examination of a particular design for the adequate safe range of operation.