Local Road Management Manual 569 • RBIVA Analytical Tools • RBIVA Reporting Tools 4. 11. In the assessment of risk, there are three (3) essential interacting components, namely : • Hazard occurrence probability, deifned as the probability of occurrence of a speciifed natural hazard at a speciifed severity level in a speciifed future time period • Elements at risk, an inventory of those people or facilities which are exposed to the hazard; and • Vulnerability, the degree of loss to each element should a hazard of a given severity occur. III. Working Deifnitions and Ratings 1. Hazards are events that can lead to loss of diversity, extent, quality and function of ecosystems. They affect the ability of an infrastructure system to support human activities. These may include natural hazards as well as man-made pressures. 2. Vulnerability is deifned as the potential for attributes of any system to respond adversely to hazardous events. It is a function of the level of defense provided by existing countermeasures in the infrastructure design. The Climate Change Act deifnes Vulnerability as the degree to which a system is susceptible to, or unable to cope with, adverse effects of climate change, including variability and extremes. It is a function of the