Orca: A risk assessment tool

A novel approach to risk assessment

Orca is the newest development realized by me at the Geography Department of the Humboldt-Universität zu Berlin. The software tool can be used for the assessment, analysis and visualization of natural hazard risk. A focus is put on the assessment of flood risk. Orca allows risk, i.e., annual average damage, to be computed by means of susceptibility functions, e.g., stage-damage functions. Those allow a damage ratio for specific evaluation criteria to be computed as a function of hazard intensity. For example, damage to buildings may be assessed as a function of inundation depth, flow velocity or flood duration. Moreover, Orca allows annual average damages to be standardized and aggregated to multicriteria flood risk. For its computations, Orca relies on raster data. At the moment, the binary grid (BGD) format and the ASCII raster format are supported. Several analysis and visualization functions for use with raster data are implemented in Orca.

Knowledge-based analysis

Orca seeks to facilitate risk assessment by means of a knowledge base. The knowledge base is geared by a Web Ontology Language (OWL) ontology that implements expert as well as local knowledge, e.g., types of hazardous events, intensity parameters, elements at risk etc. Thereby, the ontology allows a user to assess risk in a purposeful and end-user oriented manner. Details on the conceptualization and implementation of both the ontology and the Orca tool can be found in the following publications: Towards a flood risk assessment ontology – Knowledge integration into a multi-criteria risk assessment approach.