BGE 214-1 Lecture 7 Natural Hazards.pdf

BGE 214-1 Geography Department of Applied Earth Sciences BGE 214-1, Geography  Natural Disasters Department of Applied Earth Sciences BGE 214-1, Geography What is a disaster...

BGE 214-1 Geography Department of Applied Earth Sciences BGE 214-1, Geography  Natural Disasters Department of Applied Earth Sciences BGE 214-1, Geography What is a disaster Emergency: a serious, unexpected, and often dangerous situation requiring immediate action Apocalypse: an event involving destruction or damage on a catastrophic scale. Calamity: an event causing great and often sudden damage or distress; a disaster. Cataclysm: a large-scale and violent event in the natural world. Catastrophe: an event causing great and usually sudden damage or suffering; a disaster. Disaster: a sudden accident or a natural catastrophe that causes great damage or loss of life. Department of Applied Earth Sciences BGE 214-1, Geography What is a natural disaster?? Natural disasters are catastrophic events that result from any of the Earth's natural phenomena Grave danger events occur in an area that can causes massive damage or loss of life Usually rare incidents Department of Applied Earth Sciences BGE 214-1, Geography Classification of natural disasters Department of Applied Earth Sciences BGE 214-1, Geography  Hydro-Meteorological Natural Disasters Department of Applied Earth Sciences BGE 214-1, Geography  Floods Floods are the most frequent type of natural disaster and occur when an overflow of water submerges land that is usually dry. Floods are often caused by heavy rainfall, rapid snowmelt or a storm surge from a tropical cyclone or tsunami in coastal areas.  The 1931 Yellow River flood is one of the most devastating natural disasters ever recorded. Department of Applied Earth Sciences BGE 214-1, Geography  Flash floods A flash flood is a rapid rise of water along a stream or low-lying urban area. That happens when rain falls so fast that the underlying ground cannot cope, or drain it away fast enough. Flash flooding commonly happens more where rivers are narrow and steep, so they flow more quickly. It can also occur from small rivers in built-up urban areas, where hard surfaces such as roads and concrete don't let the water drain away into the ground. This leads to surface overflow and can often overwhelm local drainage systems, leading to flash flooding. Department of Applied Earth Sciences BGE 214-1, Geography  Coastal flood Coastal flooding is a flood that occurs when (often low-lying) land that is usually dry is flooded with seawater. Storm surges, hurricanes, tropical storms, and rising sea levels as a result of climate change and tsunamis are all responsible for coastal flooding. A lot of coastal flooding is a result of storm surges. Storm surges are short-term changes in sea levels caused by events such as tsunamis and cyclones. A storm surge is only measured by the water level that exceeds the normal tidal level, excluding waves. Department of Applied Earth Sciences BGE 214-1, Geography  Cyclones, Typhoons and Hurricanes A storm is generally referred to as a Cyclone, Hurricane or Typhoon based on where the storm takes place. Cyclones take place over the Indian Ocean Hurricanes take place over the North Atlantic Ocean Typhoons take place over the Pacific Ocean Department of Applied Earth Sciences BGE 214-1, Geography Tornadoes Tornadoes – is a violently rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud Department of Applied Earth Sciences BGE 214-1, Geography El Niño and La Niña “El Niño” happens when the surface waters of the Pacific Ocean getting warmer than usual, off the coasts of Peru and Ecuador. This can cause floods, drought, wildfires and other hazards in America, Latin America, Austrailia and other parts of the world. Department of Applied Earth Sciences BGE 214-1, Geography  A normal year Normal conditions are: high pressure exists in the eastern Pacific, low pressure in the western Pacific surface trade winds blow east to west across the Pacific Ocean, with compensatory upper atmosphere westerly winds (the Walker Circulation) these push warm water across the sea surface from east to west upwelling of cold water takes place off the west coast of Peru, together with more cold water supplied by the cold Peruvian ocean current dry weather exists in coastal Peru, with rain in northern Australia. Department of Applied Earth Sciences BGE 214-1, Geography  An El Niño year In an El Niño year: the trade winds become weaker, and may even reverse low pressure develops over the eastern Pacific, with high pressure to the west warm water replaces cold water off the coast of Peru waters off the coast of northern Australia become cooler rainfall totals in northern Australia and Indonesia reduce, and the dry conditions often spread to India and southeast Asia rain falls in northwestern South America Department of Applied Earth Sciences BGE 214-1, Geography  El Nino impacts In South America, there are a variety of impacts: an increased possibility of flooding on the western coast of northern South America drier conditions east of the Andes, in Amazonia wetter conditions in southern Brazil and northern Argentina In Australia and the western Pacific basin: weaker monsoons across much of Asia reduction in number and intensity of tropical storms an increase in wildfires with the drier conditions Department of Applied Earth Sciences BGE 214-1, Geography A La Niña year La Niña events act independently – they are not associated with El Nino events: they involve the build-up of cooler-than- usual subsurface water in the eastern Pacific Ocean very warm waters build up in the western Pacific they create severe drought conditions in the eastern Pacific coastlands/western and southern South America very wet weather can be experienced in northern Australia and Indonesia Department of Applied Earth Sciences BGE 214-1, Geography Global changes to rainfall and drought in a La Niña year Department of Applied Earth Sciences BGE 214-1, Geography  La Niña impacts A variety of global phenomena have been linked to La Niña events: flooding in Queensland, Australia in 2010/11 – more than 80 people were killed heavy snowstorms in northern USA/southern Canada in 2010 strong tornadoes in the southern USA in 2011 increases in transmissible diseases in wetter areas, e.g. malaria in southeast Asia and Australian encephalitis (or Murray Valley encephalitis), in southeast Australia Department of Applied Earth Sciences BGE 214-1, Geography Department of Applied Earth Sciences BGE 214-1, Geography  Drought Drought is a prolonged dry period in the natural climate cycle that can occur anywhere in the world. It is a slow-onset disaster characterized by the lack of precipitation, resulting in a water shortage. Ex: 1900 India killing between 250,000 and 3.25 million. 1921–1922 Soviet Union in which over 5 million perished from starvation due to drought. It can have a substantial impact on the ecosystem and agriculture of the affected region and harm to the local economy. Annual dry seasons in the tropics significantly increase the chances of a drought developing and subsequent bush fires. Department of Applied Earth Sciences BGE 214-1, Geography  Wild fire Wild fires are large fires outdoor that can burn for days on many acres. It can be described as any uncontrolled and non-prescribed combustion or burning plants in a natural setting such as a forest, grassland and bushland, which consumes the natural fuels and spreads based on environmental conditions. Department of Applied Earth Sciences BGE 214-1, Geography  Extreme temperature Extreme temperature is defined as summertime temperatures that are much hotter and/or humid than average. Some factors that might increase your risk of developing a heat-related illness include:  High levels of humidity  Obesity  Fever  Dehydration  Prescription drug use Department of Applied Earth Sciences BGE 214-1, Geography Heat Wave Heat wave – a period of excessively hot weather. A heat wave can have devastating effects on crops, animals and people. Extreme heat can often contribute to other natural disasters such as droughts (prolonged shortage of water). Department of Applied Earth Sciences BGE 214-1, Geography Human disasters A disaster caused by human action. These include oil spills, chemical explosions and gas leaks in factories. Department of Applied Earth Sciences BGE 214-1, Geography Department of Applied Earth Sciences BGE 214-1, Geography Department of Applied Earth Sciences BGE 214-1, Geography  Natural Disasters in Sri Lanka Heavy rains Floods Landslides Heat waves Droughts Tornadoes / Hurricanes / Cyclones / Typhoons Volcanoes Earthquakes Tsunamis Winter Storms / Avalanches Wildfires Department of Applied Earth Sciences BGE 214-1, Geography  2021 2022 Department of Applied Earth Sciences BGE 214-1, Geography  2021 Department of Applied Earth Sciences BGE 214-1, Geography Department of Applied Earth Sciences BGE 214-1, Geography Department of Applied Earth Sciences BGE 214-1, Geography  Preventing natural disasters  Sendai Seven campaign for reducing natural disasters  Awareness, education, preparedness, and prediction and 2016: To reduce disaster mortality. warning systems can reduce the 2017: To reduce the number of people affected. disruptive impacts of a natural 2018: To reduce economic losses. disaster on communities. 2019: To reduce disaster damage.  Mitigation measures such as 2020: To increase the number of countries with response strategies. adoption of zoning, land-use 2021: To increase international cooperation with practices, and building codes are developing countries. needed, however, to prevent or 2022: To make warning systems more readily reduce actual damage from available. hazards. Department of Applied Earth Sciences BGE 214-1, Geography  Weather Disasters total for over 130 billon USD in 2022 Department of Applied Earth Sciences BGE 214-1, Geography Department of Applied Earth Sciences BGE 214-1, Geography