MIRISK Overview
A Natural Disaster can destroy years of Development in a few seconds.
This is because building design codes are only a minimum level of design.
That is, the purpose of normal building design codes is not to eliminate all damage given a major earthquake, flood or tropical cyclone. Rather, the code's purpose is to prevent major loss of life - significant damage is acceptable per modern building codes, if not many people die. It can be very wise, and cost-effective, for a Development Manager to require a moderately enhance level of construction for natural hazards for a Project. This is especially true when one considers the total costs of damage, in terms of Project loss of use ("business interruption").
MIRISK (Mitigation Information and Risk Identification System) is a tool to help Development Managers consider natural hazards risk, and ways to reduce that risk, by:
- identifying natural hazards affecting a region
- defining the kinds of infrastructure ("assets") that make up typical Development projects
- describing the vulnerability of these assets to natural hazards, and how vulnerability can be reduced
- analyzing the natural hazards and vulnerability data, to assess whether Projects should follow normal design practices, or whether the cost of some enhanced design for natural hazards is justified by the benefits (of avoided losses).
Natural hazards currently considered are earthquakes, flood, tropical cyclone, and volcanism.
MIRISK's basic purpose is to allow a Development Manager to quickly learn if natural hazards are very significant in a region where the Manager is considering development. If so, MIRISK provides information on what can be done, and permits estimation of the added cost for a moderately enhanced level of construction for natural hazards. An 'optimum' level of enhanced construction is estimated, based on the degree of hazard, the type of facility, and the Project's benefit cost ratio (BCR, used to account for indirect costs of damage).
MIRISK Work Flow
A MIRISK user accesses four basic tabs or screens:
- Project Data
- Location/Hazard Data
- Component (Asset) Data
- Analysis/Report
as well the Main, Help, About and Feedback tabs. Tabs 1-4 however are all that need be followed to perform an analysis. Sections 3.1 to 3.4 describe Tabs 1-4.
Project Data
This screen is for administrative purposes - the user enters data for a new project, or resumes a previously saved project. Information recorded here are project identifier data, users names, and related information needed for administrative purposes.
Location/Hazard Data
The first step in risk analysis is to learn if a project component is located in a high hazard region (ie, what nature may put there).
When the LOCATION/HAZARD tab is clicked, a map of the world is seen (and possibly some components numbers showing the Users previously identified component). Users locate their component by:
- Clicking on Zoom In, and draw a box around a region, and so on, to zoom into the region of interest.
- Entering lat/long, or
- Entering a place name (which is searched for via a built-in gazetteer).
When the region is located, the degree of Earthquake, Wind, Flood or Volcano risk for a region can be seen via color codes (click Key tab on the bottom to see the degrees of risk, which are explained further below, under HAZARD DATA).
The LAYERS tab on the left controls what is visible on the map - all Hazards, Components and other information can be turned on or off. The map can also be queried to learn the degree of risk at any location.
Component (Asset) Data
The second step in risk analysis is to define what the component consists of, in terms of types of facilities and construction (ie, what you are thinking of putting there).
On the page you define your component by clicking on some menus, and MUST input ASSET VALUE DATA (e.g. anticipated component cost, for construction and including overhead) and component BENEFIT COST RATIO (BCR). The component cost and BCR are used for a benefit-cost assessment. BCR is the estimate of the total component benefit (including some monetized estimate of future social benefits), divided by the total component cost.
To Define the component when the ASSET tab is clicked, you can either:
- Retrieve an existing component, using the menus on the left, or
- Define a new Asset, using the menus on the right. These menus first ask you to define one of three ASSET CATEGORY:
- Buildings
- Transportation
- Utilities / Industry
- For each of the three Asset Categories, the User then defines a CATEGORY CLASS, such as
- Buildings
- Wood
- Light Metal
- Low-rise Reinforced Masonry or Reinforced Concrete, etc
- Transportation
- Bridges, conventional
- Bridges, Major
- Tunnels, etc
- Utilities / Industry
- Chimneys
- Cranes
- Conveyor systems etc
- Buildings
When the Category Class (e.g. Low Rise Reinforced Masonry or Reinforced Concrete) is selected, the DESCRIPTION, DAMAGE AND DESIGN INFORMATION ON ASSETS pane changes, to provide photographs and a description of the class, its Vulnerability to various hazards and how to reduce (mitigate) the vulnerability. By reading these descriptions, a Development Manager can quickly gain some familiarity with what these various Classes are, how they are damaged by natural hazards and, in general, what are some of the techniques used to reduce their vulnerability to natural hazards. This information provides a good background for users not expert in natural hazards mitigation.
Analysis/Report
This MIRISK tab summarizes the input information, and uses it to estimate:
- potential losses due to a natural hazard for the identified site and
- the cost of enhanced design for that hazard, to identify if enhanced design may be warranted, given the regional hazards for the project location and the value of the project.
The page can be printed out (hard copy or pdf) as a report for your project, using the icons on the upper right.
The Results are provided for the various hazards, and consist of the expected cost of construction for minimum code, and for some moderately enhanced level of construction (for natural hazards). The enhanced level is shown as a factor (eg, 1.02) which represents designing the component (asset) for "2%" more than the minimum code requirement for the component for that site. Enhancing the level of construction increases the cost of construction, and an estimate of that increased cost is shown in the table on this tab.
When a natural hazard occurs, such as an earthquake or tropical cyclone, damage is likely to occur, especially if the component was designed only per the minimum building code requirements. This is because the purpose of normal building design codes is not to eliminate all damage given a major earthquake, flood or tropical cyclone. Rather, the code's purpose is to prevent major loss of life - significant damage is acceptable per modern building codes, if not many people die.
Therefore, the cost of damage and associated losses are estimated for minimal code level design. The technical details of this estimation are discussed further below, but basically the MIRISK estimates the cost of damage from a database of such costs for various hazards and types of facilities. It includes in this loss estimate not only the direct cost of repairs to the facility, but also the associated costs of loss of use of the facility (eg, renting another facility while the first is repaired). These associated costs are estimated using the BCR input by the User.
In return for the increased expenditure for natural hazards, the enhanced level of construction should have less damage when a natural hazard occurs. Therefore, the cost of damage and associated losses are estimated for not only for minimal code level design, but also for each level of design, from 1.0 (minimum code requirement) to 1.4 (40% greater than minimum code). These are tabulated in the Results Table.
Lastly, the Total Cost of the component, which is the sum of the cost of construction (increasing with enhanced level of design) plus the cost of damage and associated losses (decreasing with enhanced level of design), are tabulated.
The minimum Total Cost is the 'optimum' enhanced level of construction design for the component.
The results are presented in tabular form, and graphically, for each hazard.
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最終更新日 2013年3月04日（月曜）12:45