Natural Hazards - #DLSGEO

Flooding often leads to loss of life as a result ofheavy flooding, causing emotional trauma for thosewho have gone through it. Even if people have notbeen directly affected by the loss of life, losingproperty, houses, or land can cause physiologicaldamage. Especially if the people affected are unableto rebuild due to the houses being too badly damage,farm land being filled with salt water, or lack ofresources to rebuild, many find the recovery to be Cattle in a flooded field in the UK.more than just physical.Damage to property during flooding is oftencan hurt anyone standing in water. If sewage or waterextensive. Vehicles should not be driven throughsystems are compromised during flooding, waterflooded areas, but often they are caught unaware,supplies can be contaminated. This can result increating the need for replacement or extensivewaterborne diseases such as typhoid or choleraamong others.Land that has be saturated often cannot grow newcrops for some time. If the water was saline, such asin flooding near the sea, land will not be able to becultivated for some years. Loss of livestock can alsoresult in farmers losing their livelihood and needingto start over with young animals means losing the South Dakota residents are dealing with a flooding nightmare.profit that would have come during that time. Anylivelihood that depends on farming or ranching can berepairs. Houses that have been flooded mildly mightseriously affected by floods as farms and ranchessurvive with just a good cleaning, but big floods oftenoften need to be near a body of water in order to live.render homes unlivable without massive repairs orrestructuring. Many personal items are lost forever,such as paper documents, photographs, clothing, andhousehold items. Furniture and woodwork are oftendamaged beyond repair and must be replaced entirely.In severe floods, communication systems can faildue to lines being broken. Power is often hindered ifpower generators and transmission is in some waydestroyed or damaged. Getting power restored after aflood is challenging as water transmits electricity and 2015 South Indian floods .11

CASE STUDY—Flooding in BangladeshBangladesh is a country that has both river andcoastal flooding.River floods result from heavy rainfall an meltingof snow in the Himalayas. Farmers rely on thefloods to supply fine silt (fertile sedimentdeposited from rivers) to the land, making it fertileand good for the growth of crops.Coastal floods are created by cyclones which pushwater in the Bay of Bengal towards the land,causing a storm surge. This floods low-lyingcoastal areas.THE 2004 FLOODSThe 2004 floods were devastating to Bangladesh.At their peak they covered over half of the countryand affected wo-thirds of the population. In manyplaces only the tops of trees and buildings could beThis led to : Floodwater up to 2 metres deep coveredthe city. Electricity was cut off for several weeks; Water in wells was polluted making itunsafe to drink and children caught fish inseen.the city streets;THE IMPACTS Small villages were cut off;Serious river flooding occurred after heavy rainfall Rice plants , sugar cane and vegetable cropswashed away and lost;in July and August which resulted in : destroyed over 8.5 million homes and made 35million people homeless. The official death toll was put at over 760 withmany others reported as missing. Most deathswere due to drowning but others were to occur Thousands of kilometres of roads, a third ofthe railway and Dhaka’s international airportwere all flooded. This made it impossible todeliver emergency food and medicalsupplies.later from diseases such as cholera.Then in September, Bangladesh had its heaviestThere was little immediate help from overseas asrainfall for 50 years. In just one day Dhaka, theglobal attention was fixed in flooding caused bycapital had 35cm of rainfall (two-thirds ofhurricanes in the USA.London’s average annual total).12

WHAT HAS BANGLADESH DONE TO COPE WITHFLOODING?Bangladesh is a very poor country and so has lessmoney to spend on flood defences than richercountries. Most people in Bangladesh do not earnenough to pay for insurance against flooding, sowhen there are floods they risk losing everything. People cut off due to flooding.SHORT-TERM RESPONSES TO FLOODING Food aid from the Government and othercountries. Water purification tablets. People repaired embankments and helped torescue people. Free seeds given to farmers.LONG-TERM RESPONSES Building embankments. Building raised flood shelters. Introducing flood warning systems. Emergency planning. Dams planned. Reducing deforestation.Unfortunately, many of these long-term responses aredifficult to pay for and maintain. They are not always City roads completely flooded in 2004.13

14In 1989 the government of Bangladesh began working with several international agencies to produce aFlood Action Plan (FAP). This huge scheme contained 26 action points which together it hoped , wouldprovide a long-term solution to the country’s serious flooding problem.CAN BANGLADESH BE PROTECTED FROM FLOODING?

Burning WILDFIRESA wildfire is an uncontrolled fire that burns in theThe dry twigs and branches on the forest floor providewildland vegetation, often in rural areas. Wildfiresfuel for the fire. Winds can fan the fire and make itcan burn in forests, grasslands, savannas, and otherspread quicker by pushing embers into part of theecosystems, and have been doing so for hundredsforest that wasn’t burning yet.of millions of years. When a heat wave or droughtdries out the plants in an area, a fire can start andspread quickly. Fires can be accidental or they canbe caused by arson or even lightning strikes.HOW CAN THEY BE STOPPED?One of the first things firemen do is to dig a gapbetween the fire and parts of the forest that are not onBecause fires can be very destructive, fire-fightersfire. They remove all of the trees and bushes in thishave developed lots of strategies for extinguishinggap. Helicopters pick up water from lakes and drop itor controlling wild fire. However, fire can alsoon the fire. They also spray a coating of chemicals onplay an important role in the life cycle of plantsthe trees that aren’t on fire. This stops the fire fromand habitats.spreading.WHERE DO THEY HAPPEN?Wild fires take place all over the world. Majorfires happen every few years in the forests of theUnited States and Indonesia, and in the bush inAustralia, however they are also common inEurope.WHERE DO THEY START?The weather has to be really hot and dry for a Wildfire caused by lightning in California.wild fire to start. When there has been no rain andit has been very hot all the branches and twigs onthe ground are very dry. This is called a drought.They can be started through natural causes such asa lightning strike or in very rare cases a volcanoerupting. 4 out of every 5 wild fires are started bypeople. Sometimes it is an accident, for examplepeople leaving a small fire burning or throwing acigarette away. Amazon forest fire covering half of Brazil.15

HOW CAN WILDFIRES BE BENEFICIAL?Still, wildfires are essential to the continued survival of some plant species and can help keep ecosystemshealthy; 16

Moving snow—AVALANCHESA snow avalanche begins when an unstable massWHAT CAUSES AVALCHES?of snow breaks away from a slope. The snow picks the air. The moving mass picks up even more snow as it rushes downhill. A large, fully developed up speed as it moves downhill, producing a river ofsnow and a cloud of icy particles that rises high intoavalanche can weigh as much as a million tons. Itcan travel faster than 320 km/hr.During an avalanche, a mass of snow, rock, ice, soil,and other material slides swiftly down amountainside. Avalanches of rocks or soil are oftencalled landslides. Snowslides, the most commonkind of avalanche, can sweep downhill faster thanthe fastest skier.EFFECTS OF AVALANCHESAn avalanche is able to obstruct anything in its path.Roads and railways can be blocked. Power supplies Skiers surprised in off-piste avalanche .can be cut off. A powerful avalanche can evendestroy buildings andpeople can also bekilled. 90 percent ofpeople who die inavalanches triggerthem themselves.People usually diefrom a lack of oxygenwhen buried in snow,rather than fromgetting too cold.17

PREDICTING AN AVALANCHEPeople try to predict when avalanches are going tooccur. The Alps has an 'avalanche season' betweenJanuary and March when most avalanches happen.Where avalanches are going to occur is hard topredict. Historical data, weather information andinformation about the actual snow on themountainside is collected together to try andforecast the likelihood of an avalanche. Avalanche hazard sign . ExplosionsAvalanches can be started deliberately in order toprevent the snow building up. This is one of themost important ways of preventing avalanches. Communicating the risk of an avalancheSigns of the risk of avalanches can be displayed invillages and also by the ski lifts. In the Alps the riskis assessed on a five-point scale. Areas can besealed off which are considered too dangerous toski on. Early warning systems are also used. Land-use zoningLand can be grouped into red, yellow and greenareas. The red areas are considered too dangerous tobe built on. The orange areas can be built on withrestrictions, such as reinforcing buildings. Roadsand railways can be protected by tunnels over themin the areas where an avalanche path is likely totravel. Snow fences and barriersThese can be used to divert and break up the path ofthe avalanche.ReforestationTrees can be planted, increasing stability of theslope and helping to reduce the damage furtherdown the valley.18

CASE STUDY— Galtür avalancheGaltür is a popular ski resort in Austria.RESPONSEAvalanches happen most years, but don't usuallyAustria had devised a new zoning system, with redreach the village of Galtür. On 23 February 1999,being an area where construction of any type isan avalanche raced down the mountain.prohibited, and yellow, where certain safety measuresare put in place. Galtur was in the yellow zone. As aresult of the avalanche, Austria has invested in theCAUSESThe Galtür avalanche was a powder avalanche- dueto a period of heavy snowfall brought on by aseries of low pressure weather systems. Eventually,the older layers of snow could not support the massof new snow, and a 50 feet high wall of snow wasformed, travelling at 200 kilometres per hour.creation of steel fences near the area to break up theimpact of the avalanche, along with trees- deforestationwas one of the possible causes of the avalanche. A 300metre long avalanche dam protects the village, and thezoning of at risk areas has been made stricter. Moreavalanche resistant buildings have been created.AFTERMATH It travelled at 200 miles per hour, taking 50seconds to reach the village. 31 people died, 26 of whom were tourists and 5were locals. Rescuers saved 26 people in thefollowing 24 hours. People in Galtür were stranded as roads wereblocked. 16 buildings were destroyed or Galtur Avalanche search for missing persons.severely damaged. Ski resorts were closed in the region, costingthe industry 5 million for each day they wereclosed. Devastating disaster. A snow mass from the avalanche penetrated the interior of ahouse.19

It’s raining mud!—MUDSLIDESA mudslide, also called a debris flow, is a type ofHOW ARE MUDSLIDES PREVENTED?fast-moving landslide that follows a channel, such asStrategies to decrease the risk of mudslides include:a river. A landslide, in turn, is simply when rock,earth, or other debris moves down a slope.Mudslides occur after water rapidly saturates the draining water off hillsides armouring the bases of hills so they are notundercut by rivers.ground on a slope, such as during a heavy rainfall.This happens when the pull of gravity is strong engineers put large rocks, at the base of a hill to tryenough to bring down material that is made fluidto anchor the slope and prevent it from comingenough by water.loose.Mudslides are also often triggered by earthquakes orIt is recommended that people exercise caution aroundby disturbances in hillsides caused by fires or humansteep slopes during rainfall. Immediate signs of aactivity.pending slide include tilting trees and sudden increasesIn the United States, mudslides and landslides resultor decreases in rivers.in an average of 25 to 50 deaths a year, according tothe Centers for Disease Control and Prevention.Deadly Colombia landslide engulfs highway near Medellin . 20

CASE STUDY— Vargas tragedyVargas tragedy is one of the worst disaster that A section of Los Corales, one of the neighbourhoods in the Vargas state whichsuffered the heaviest destructionstruck the Venezuelan country's Vargas state on 15December 1999. It was a result of heavy downpourof rain, flash floods and mudslides that followedon 14-16 December 1999 . This disaster led to ancomplete collapse of the infrastructure of the state ofVargas.Many towns were swept away to the ocean due tothe floods. Whole towns like Cerro Grande andCarmen de Uria completely disappeared. As muchas 10% of the population of Vargas perished duringthis event. The coastal area of Vargas has long beensubject to mudslides and flooding: geologicallysmall communities that were completely wiped out;similar catastrophes occurred with regularity. Themoreover, only some 1,000 bodies were recovered,most recent major flood was in 1951, however thatevent did not cause as much damage.In a 52-hour span during 14, 15 and 16 December1999, 91.1 cm of rain (approximately one year's totalwith the rest swept to sea by the mud or buried in thelandslides. More than 8,000 homes and 700 apartmentbuildings were destroyed in Vargas displacing up to75,000 people.rainfall for the region) was measured on the northcentral coast of Venezuela. Even so, the coastreceived much less rain than some regions upstream.The disaster caused estimated damages of USD 1.79to 3.5 billion. The death toll was considered to bebetween 10,000 and 30,000—the exact number ofShanty towns hit hardest by Venezuelan Floods / Shacks, people on steep slopesjust swept away. casualties is difficult to determine as there was noreliable census data, especially about shanty towns and Remains after the mudslide.21

Glossaryavalanchea mass of snow, ice, and rocks falling rapidly down a mountainside.climate changea change in global or regional climate patterns.cyclonea system of winds rotating inwards to an area of low pressure.droughta long period of abnormally low rainfall, leading to a shortage of water.flash floodsa sudden floods, typically due to heavy rain.landslidea collapse of a mass of earth or rock from a mountain or cliff.leveesa ridge of sediment deposited naturally alongside a river by overflowingwater.mudslidesa mass of mud and other earthy material that is falling or has fallen down ahillside or other slope.natural hazarda natural phenomenon that might have a negative effect on humans or theenvironment.tropical stormvery intense low-pressure wind system, forming over tropical oceans andwith winds of hurricane force.wildfirea large destructive fire that spreads quickly over woodland or bush.22

Natural hazards are extreme natural events that can cause loss of life, extreme damage to property and disrupt human activities. Some natural hazards, such as flooding, can happen anywhere in the world. Other natural hazards, such as tornadoes, can only happen in specific areas. And some hazards need climatic or tectonic conditions to