Drought in Australia Definition: A drought is a prolonged, abnormally dry period when there is not enough water for users’ normal needs. Drought is not simply low rainfall; if it was, much of inland Australia would be in almost perpetual drought. Because people use water in so many different ways, there is no universal definition of drought. Drought occurs because rains are unreliable and in some years the ITCZ (Inner Tropical Convergence Zone = area of rainfall) may not move so far north.
Thus hot, dry tropical continental air dominates for the whole year. Drought in Australia Australia is prone to drought because of its geographic location. Much of Australia lies in a latitude belt that is under the influence of an atmospheric phenomenon known as the subtropical high. Just outside of the tropics in each hemisphere lies a swath of the globe where air frequently sinks toward the Earth’s surface from higher in the atmosphere.
The air warms and dries as it sinks, creating semi-permanent zones of high air pressure at the surface. These subtropical highs are areas of stable, warm, and dry air that favour clear skies and little rainfall Where: most common in the middle of Australia (the lower you go, the drier it gets) When: Drier than average conditions tend to occur over Australia during periods of El Nino. This is due to increased amounts of sinking air in that area which acts to suppress rainfall. (El Nino translates from Spanish as ‘the boy-child’.
Peruvian anchovy fishermen traditionally used the term – a reference to the Christ child – to describe the appearance, around Christmas, of a warm ocean current off the South American coast, adjacent to Ecuador and extending into Peruvian waters. ) Predictibility: * Variable rainfall * Depends on the spatial elements of the area Magnitude: * Lack of rain causes * absolute drought (a period of at least 15 consecutive days with less than 0. 2 mm of rainfall) * partial drought (a period of at least 29 days with the average day rainfall not exceeding 0. 2 mm of rainfall) Frequency: Dry areas and arid condition * subtropical high pressure area (around 20 – 30 N) * Distance from sea (continentality) limits the amount of water carried across by winds * cold offshore currents limits the amount of condensation into the overlying air example: Atacama and Namib deserts * human activities affect the frequency of droughts –> desertification Duration: * About 15 days – 3 years * Even decades Speed of onset: * This depends on the climate and spatial elements * usually long and slow drought one takes more than month Why did the hazard event occur?
Australia has one of the most variable rainfall climates in the world. The strongest one is called the Southern Oscillation. It is a major air pressure shift between the Asian and East Pacific regions. El Nino is the name of the most extreme phenomenon which makes drought a regular event in Australia which can last about 1 year. The reason for Australia being highly affected of drought simply is its geography. Due to the fact that the country is situated more or less in the subtropical hight pressure belt unregular weather events such as rain deficiency occur very often.
They can’t be avoided or prevented so that the Australian population has to be concious about the fact that there will always be droughts in Australia which might not happen regularly, but definetely will take place. What geo-physical processes are responsible for the hazard event/disaster? Droughts depend on water vapor in the air and the upward forcing of it. If these two factores are inbalanced the result is a drought. The high pressure conditions in the Tropic of Capricorn prevent the forming of rain and storms.
When winds that carry rather continental than oceanic airmasses (containing less moisture) and high pressure areas meet, the result are behaviours which prevent precipitation or the developing of thunderstorms in certain regions. The areas most affected in Australia are the far North and South. What specific geographical characteristics of the place affect its level of vulnerability? Because the speed of onset of a drought is very slow there are no warning systems which could forecast the exact starting point of a drought. This is bad because the population cannot prepare. Agriculture is probably most affected.
Farmers suffer for the reason that there are no alternative food sources. The soil in Australia only allows them to grow a specific number of types of crops – which makes them more vulnerable to the hazard. The effects of major drought| 1864-66| All States affected except Tasmania. | 1963-68| Widespread drought. Also longest drought in arid central Australia: 1958-67. The last two years saw a 40 per cent drop in wheat harvest, a loss of 20 million sheep, and a decrease in farm income of $300-500 million| 1880-86| Southern and eastern States affected. | | | 1895-1903| Sheep numbers halved and more than 40 per cent loss of cattle.
Most devastating drought in terms of stock losses. | | | 1911-16| Loss of 19 million sheep and 2 million cattle. | 1972-73| Mainly in eastern Australia. | 1918-20| Only parts of Western Australia free from drought. | 1982-83| Total loss estimated in excess of $3000 million. Most intense drought in terms of vast areas affected. | 1939-45| Loss of nearly 30 million sheep between 1942 and 1945. | 1991-95| Average production by rural industries fell about 10 per cent, resulting in possible $5 billion cost to the Australian economy, $590 million drought relief provided by the Commonwealth Government between September 1992 and December 1995. Drought’s impacts During climate extremes, whether droughts or flooding rains, those on the land feel it most. Agriculture suffers first and most severely – yet eventually everyone feels the impact. Drought disrupts cropping programs, reduces breeding stock, and threatens permanent erosion of the capital and resource base of farming enterprises. Declining productivity affects rural Australia and the national economy. The risk of serious environmental damage, particularly through vegetation loss and soil erosion, has long term implications for the sustainability of our agricultural industries.
Water quality suffers, and toxic algae outbreaks may occur; plants and animals are also threatened. Bushfires and duststorms often increase during dry times. Hunger and famine—Drought conditions often provide too little water to support food crops, through either natural precipitation or irrigation using reserve water supplies. The same problem affects grass and grain used to feed livestock and poultry. When drought undermines or destroys food sources, people go hungry. When the drought is severe and continues over a long period, famine may occur.
Thirst—All living things must have water to survive. People can live for weeks without food, but only a few days without water. Disease—Drought often creates a lack of clean water for drinking, public sanitation and personal hygiene, which can lead to a wide range of life-threatening diseases. Wildfires—The low moisture and precipitation that often characterize droughts can quickly create hazardous conditions in forests and across range lands, setting the stage for wildfires that may cause injuries or deaths as well as extensive damage to property and already shrinking food supplies.
Social conflict and war—When a precious commodity like water is in short supply due to drought, and the lack of water creates a corresponding lack of food, people will compete—and eventually fight and kill—to secure enough water to survive. Migration or relocation—Faced with the other impacts of drought, many people will flee a drought-stricken area in search of a new home with a better supply of water, enough food, and without the disease and conflict that were present in the place they are leaving.
In a country such as Australia where droughts continue for years, this may have the following effects: * hinders a farmer’s income by limiting his ability to produce crops and/or healthy livestock * drives up prices of goods due to limited supply * increases inflation as a result of price increases * contributes to unemployment as businesses, suffering loss of profits, are forced to close down and farms are forced to sell up * increases the danger of bushfires, duststorms and other drought-related natural disasters * increased desertification, i. . once fertile land becomes desert, a situation from which the land rarely recovers * causes people to relocate, thus contributing to the death of towns * causes death to native animals, not only from lack of food and water, but also because drought can drive introduced species such as foxes and feral cats, which tend to be hardier than the native animals, to kill more native animals in the quest to survive. In less developed countries, drought leads to famine. It also causes diseases as there is less water available for basic hygiene and sanitation.
Although not yet an issue in Australia, wars have even been fought over access to available water. SOCIAL: Research indicates that social impacts as a result of drought on individuals, families and communities may include: ?? people being reluctant to get involved in community activities ?? a decline in traditional industries ?? volunteer stress or burnout, or an inability to even have a volunteering effort ?? the need to and or ability to seek off-farm work ?? increased financial pressures ?? decline in the health (both physical and mental health) of individuals and their families ?? dealing with questions of whether to leave the farm and/or problems associated with succession planning ?? a loss of local farm labour ?? an inability to leave the property because of the demands of feeding and water regimes ?? the local economy impact from a postponement of capital purchases as a result of drought ?? a general increase of working hours with little opportunity for recreation and family time.
How individuals, families and communities deal with these challenges depends on the provision of services, infrastructure and the way they improve relationships. ECONOMIC: A drought has a large impact on agricultural production: * Almost 40% of farmers and farm managers reported that drought had reduced property output to its lowest point ever or eliminated it completely. * A further third said it had reduced property output substantially. * Only about 8% of farmers said that their properties’ output was not or only a little affected.