Comprehensive Risk Assessment for Natural Hazards - Planat

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Comprehensive risk assessment for natural hazards 15 building codes had not been properly enforced during the relatively quiet period preceding Andrew. 2.6.2 Steps in risk assessment Risk is evaluated in terms of the consequences of a disaster including lives lost, persons injured, property damaged and economic activity disrupted. Risk is the product of hazard and vulnerability. Thus, risk assessment combines hazard assessment with the vulnerability of people and infrastructure. Assessment of meteorological hazards should invariably go through the following steps. (a) Forecasting and warning needs: — Location of area at risk — Type of forecast or warning — Required lead time — Required accuracy; (b) Data collection: — Number of satellite pictures available — Availability of other types of data such as synoptic, aircraft-reconnaissance flight reports — Manner and timeliness of reception; (c) Processing and analysis of data; (d) Transmission of data: — Availability and types of transmission system — Reliability — Timeliness; (e) Accuracy of forecast and warning. It is then considered more appropriate to divide the exercise of risk assessment into two parts with respect to the time horizon of the consequences of the disaster: (a) Short-term risk assessment, and (b) Medium- and long-term risk assessment. The short-term risk assessment is concerned with: (a) Threat to human life; (b) Damage to crops and industries; (c) Damage to human settlements; (d) Disruption of transportation;and (e) Damage to power and communication services. In addition to the short-term risk assessment, the medium- and long-term risk assessment are concerned with: (a) Socio-economic consequences; (b) Pest and disease occurrence and propagation; (c) Cost of refurbishing or relocating human structures and related infrastructure; (d) Number of beach areas impacted; and (e) Damage to the tourist industry. When hazard warnings are issued by the meteorological service, a whole series of step-by-step actions is unleashed. These actions may be divided into four parts: (a) General preparedness; (b) The approach of a hazard; (c) During the hazard; and (d) The aftermath. In all of these, the following departments will be involved: (a) Meteorological service; (b) Radio and television broadcasting service; (c) Ministry of Information; (d) Ministry of Social Security; (e) Power and water utilities; and (f) Police and the army. 2.6.3 Phases of hazard warning 2.6.3.1 General preparedness To better coordinate action plans, it is useful to form local hazard committees in each town and district. These committees should liaise with the authorities and organize refugee centres and ensure that all requirements are in place to receive the refugees. Emergency lighting and power must be verified and adequate stocks of fuel must be prepared by such committees since power may be disrupted. At the beginning of holiday periods or weekends, arrangements must be made for personnel to be available for more elaborate precautions. In the long term, it is essential, so as to minimize the impact of meteorological hazards, for the scientific community to impress upon decision makers the need to review planning strategies, and to reorganize urban areas. In this context, the WMO-initiated Tropical Urban Climate Experiment (TRUCE) has consolidated the foundation for studies of urban climates with their human and environmental impacts. 2.6.3.2 The approach of the phenomenon As soon as a phenomenon starts to approach the vicinity of a country, and danger of destructive gusts or intense precipitation increases, warning systems are enforced. When gusts become frequent and reach, say, 120 km/h, overhead power and telephone lines will start being affected. To ensure continued communication, especially between the meteorological service and the radio service, the police or army should arrange for manned HF radio-telephone transceivers to operate on their network (Prime Minister’s Office, 1989). Other key points, such as the police/army headquarters,harbour,airport and top government officials should be hooked on this emergency communication network. Instructions will be given to stop all economic, social and school activities. Well-conditioned schools may be used as refugee centres. 2.6.3.3 During the phenomenon During an event (mainly tropical or extratropical storm or prolonged periods of heavy precipitation), movement of services outside may become very difficult. Mobility of those employed by essential services may be possible only with the help of heavy army trucks. The population will be warned to stay in safe places and should refrain from attempting to rescue belongings outdoors or remove or dismantle television aerials and other fixtures.
16 2.6.3.4 The aftermath Immediately after the occurrence of an event, the emergency relief operation will be directed from a central point, which could be even the office of the head of government. Liaison would be through the local committees that would be responsible for collecting information on the general situation throughout the disaster-stricken area, such as the damage to government and non-government property. The local committees would also make recommendations and/or decide on any relief measures immediately required; and provide an accessible central reporting point for Heads of Ministries/Departments primarily concerned in the work of relief and construction. Immediate steps will be taken to: (1) Reopen roads (for example, by the army); (2) Restore water supplies; (3) Restore essential telephones; (4) Restore power and lighting; (5) Reopen the port and the airport; (6) Assess damage to food stocks; (7) Organize scavenging services; (8) Provide and maintain sanitary arrangements at refugee centres and throughout the country; and (9) Salvage damaged property and restore ministries/ departments to full operational efficiency. In the medium term, steps will be taken to locate and disinfect stagnant pools of water, and reorganize industry and agriculture. 2.7 CONCLUSION Precautions cost money and effort and must be regarded as an insurance against potential future losses from meteorological events, but not as a prevention of their occurrence. Not investing in prompt and adequate measures may have extremely serious consequences. The formation, occurrence and movement of meteorological events and their forecasted future state provides important hazard and risk-management information, which may require the enhancement of existing techniques and services. To reduce the impact of meteorological hazards, governments should actively undertake to: — uplift the living standard of the inhabitants to enable them to acquire basic needs and some material comfort; — consider judicious planning in human settlement and land use; — set up efficient organization for evacuation and convenient shelters for refugees; — take steps so that return periods of extreme events become a design consideration, and enforce appropriate specifications of design wind velocities for buildings; — give high priority to updating disaster plans. This should be a sustained effort rather than undertaken after the occurrence of a recent event. 2.8 GLOSSARY OF TERMS Coriolis force is the force which imposes a deflection on moving air as a result of the earth’s rotation. This force varies from a maximum at the poles to zero at the equator. Cumulonimbus clouds, commonly known as thunderclouds, are tall clouds reaching heights of about 15 km. These clouds are characterized by strong rising currents in some parts and downdraft in others. Extratropical storms are storms originating in subtropical and polar regions. Eye of the storm is an area of relatively clear sky and is calm. The eye is usually circular and surrounded by a wall of convective clouds. Geostationary satellites:Meteorological satellites orbiting the earth at an altitude of about 36 000 km with the same angular velocity as the earth, thus providing nearly continuous information over a given area. Heavy rain is a relative term and is better described by intensity, measured in millimetres or inches per hour. Meteorological drought is commonly defined as the time, usually measured in weeks, months or years, wherein the atmospheric water supply to a given area is cumulatively less than climatically appropriate atmospheric water supply (Palmer, 1965). Squall lines are non-frontal lines with remarkably strong and abrupt change of weather or narrow bands of thunderstorm. Storm bulletin is a special weather message providing information on the progress of the storm still some distance away. Storm procedures comprise a set of clear step-by-step rules and regulations to be followed before, during and after the occurrence of a storm in a given area. Storm surge is defined as the difference between the area sea level under the influence of a storm and the normal astronomical tide level. Storm warnings are messages intended to warn the population of the impact of destructive winds. Tornadoes are strong whirls of air with a tremendous concentration of energy and look like dark funnel-shaped clouds, or like a long rope or snake in the sky. Tropical storms are areas of low pressure with strong winds blowing in a clockwise direction in the southern hemisphere and anticlockwise in the northern hemisphere. They are intense storms forming over the warm tropical oceans and are known as hurricanes in the Atlantic and typhoons in the Pacific. 2.9 REFERENCES Chapter 2 — Meteorological hazards Cunnane, C., 1978: Unbiased plotting positions — a review. Journal of Hydrology, Vol. 37 No. (3/4), pp. 205-222. Dvorak, V.F., 1984: Tropical Cyclone Intensity Analysis Using Satellite Data. NOAA Technical Report NESDIS II, U.S. Department of Commerce, Washington D.C., 47 pp. Gore, R., 1993: National Geographic Magazine.April.
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Page 4 and 5: CONTENTS AUTHORS AND EDITORS . . .
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CHAPTER 8 STRATEGIES FOR RISK ASSES
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