Desert Knowledge CRC Data Project - Resource material on desert Australia

This map show the boundaries within which the DKCRC operates. Australia is the driest inhabited continent in the world; 70% of it is either arid or semi arid land. The arid zone is defined as areas which receive an average rainfall of 250mm or less. The semi arid zone is defined as areas which receive an average rainfall between 250-350mm. Rangelands info link: http://audit.ea.gov.au/ANRA/rangelands/rangelands_frame.cfm?region_type=AUS&region_code=AUS&info=description

Deserts 

The Year Book of Australia, 2006 has a feature article on Australian deserts, for the International Year of Deserts and Desertification. Included are feature articles on climatic aspects, the archaeology and environmental history, and the vegetation and wildlife of Australia's deserts.

• Australian Deserts, Climatic aspects of Australia's deserts
• Australian Deserts, Deserts past - the archaeology and environmental history of the Australian deserts
• Australian Deserts, Desert wildlife of Australia
• Assisting countries combat desertification - Australia's role
  

Australian Government Department of the Environment and Heritage International Year of Deserts and Desertification links.

• http://www.deh.gov.au/events/iydd/index.html (includes a map of Australian deserts)

Agro-climatic zones

The climate in arid Australia is generally unpredictable and extreme, with low and infrequent rainfall, high temperatures and high rates of evaporation. The average annual rainfall in the desert is <250mm, and the average number of rain days per year is less than 40. Long periods of drought can be followed by short, but intense bursts of rain, causing a sudden boost in the regeneration of plants and animals.

The relatively flat terrain of inland Australia makes it susceptible to the effects of coastal weather systems as there are no mountain ranges to block the movement of moisture. In the North, summer rain is usually a result of either monsoon troughs extending inland or also from the residual effects of tropical cyclones, in particular affecting the North West. Cloud bands that from the Indian Ocean often bring rain as they move South East across the desert. In the South, high pressure systems move northwards bringing moisture inland.

The high temperatures and dry climate in the desert also result in high rates of evaporation. This makes it difficult for many land types to hold the water after rain for a long period of time. Plants and animals must react quickly and rapidly to take advantage of any moisture while it is available.

The climatic zones shown on this map are adapted from a global agro-climatic classification (Hutchison et al., 1992). It is a classification which takes into account rainfall, temperature, season and the effects on plant growth. There are 18 classes of this global classification which are found in Australia:

B1 - Very cold winters with summers too short for crop growth

B2 - Less severe winters and longer moist summers suitable for some crops

D5 Moisture availability high in winter-spring, moderate in summer, most plant growth in spring

E1 Classic “Mediterranean” climate with peaks of growth in winter and spring and moderate growth in winter

E2 “Mediterranean” climate, but with drier cooler winters and less growth than E1

E3 Most plant growth in summer, although summers are moisture limiting. Temperature limits growth in winter

E4 Growth is limited by moisture rather than temperature and the winters are mild. Growth is relatively even through the year

E6 Semi-arid climate that is too dry to support field crops. Soil moisture tends to be greatest in winter

E7 Moisture is the main limit on crop growth. Growth index lowest in spring

F3 Cooler end of the warm, wet sub-tropical climates

F4 Warmer and wetter than F3

G Desert, supporting very little plant growth due to water limitation

H Semi-arid, with some growth in the warm season, but too dry for cropping

I1 Strongly developed wet and dry seasons with plant growth determined by moisture availability

I2 Temperature and moisture are more seasonal than for I1 and the growing season is shorter

I3 This has cooler winters than I1 and I2 with a growing season lasting at least six months

J1 Moisture and temperature regime supports growth for 8–9 months of the year, with a 3–4 month dry season

J2 As for J1 but with a shorter dry season

(Source: Michael F. Hutchinson, Sue McIntyre, Richard J. Hobbs, Janet L. Stein, Stephen Garnett and Janine Kinloch. Integrating a global agro-climatic classification with bioregional boundaries in Australia. Global Ecology and Biogeography, (2005) 14, 197-212)
 

 
Moisture index

There are many different methods that can be used to characterise Australia’s desert areas. An important factor that influences deserts is the amount of available moisture, as this affects the growth and distribution of plants. The map shown here has been constructed using a moisture index. A moisture index is calculated by dividing the amount of rainfall (mm) by the evaporation rate (mm). It measures the ratio of moisture lost through evaporation, compared to moisture gained from rainfall.

The moisture index was used to divide the desert into arid and semi arid zones. The arid zone on this map is defined as areas with a moisture index of less than 0.2. The semi arid zone has a moisture index between 0.2 and 0.4. A value less than 1.0 indicates that moisture lost through evaporation exceeds moisture gained from rainfall. This demonstrates that the rate of evaporation greatly exceeds the amount of rainfall, resulting in the rapid disappearance of water from the rare rainfall events.

Koeppen classification system

This map shows Arid (desert) and Semi-Arid (grassland) areas of Australia as based on a modified version of the Koeppen classification of world climates.

For an explanation of the modified Koeppen classification see Objective Classification of Australian Climates from the Bureau of Meteorology website

The Bureau of Meteorology website also shows maps of Australian climate classifications including the Koeppen map in more detail.

More climate information from Bureau of Meteorology can be found in the links to resources section at the end of this page.

Rainfall

This map shows the long term average annual rainfall.  Rainfall in desert Australia is very infrequent, unpredictable and highly variable. The variable nature of rainfall in the desert means that in one year less than half the long term annual average can fall, and in another year this annual average can fall in a matter of days.

The driest stretch of arid Australia has an annual average below 200mm and extends from the West coast across the arid interior all the way to SW QLD and NW NSW. The driest part of Australia is around Lake Eyre in South Australia, with an average of 150mm per year. In contrast, the wettest part of Australia (North East coast of Queensland) exceeds 3000mm per annum.

Australia's Climate information from the ABS

Population centres in the rangelands

With most of Australia’s population concentrated on the coastal fringe, the arid and semi-arid zones comprise only 3% of Australia’s population (573 000 people), with 20% of this consisting of a growing and diverse Indigenous population. Although a small percentage of Australia's population lives in the desert, the area contains important industries, Australia, natural and cultural values.

The construction of the Overland Telegraph line in the 1870s first opened up the opportunity for industries to be established in the desert. These included pastoralism, mining, tourism and defence.  The pastoral industry has been the economic backbone of the arid regions, and occupies a significant area of land. Today, tourism is becoming economically significant and in many regions has overtaken pastoralism as the key income generator. There is also a growing industry in native foods and Indigenous arts and crafts.

Desert settlements

Indigenous population centres

Aboriginal people have inhabited remote areas of desert Australia for around 40 000 years. Their extensive and in depth knowledge of the desert landscape and ecology meant they could find food and water even in the driest of times. This land is still of great traditional and spiritual importance to them.

There are now approximately 1300 Aboriginal commuities across desert Australia and many of these support less than 50 people. They exist in some of the most remote and least disturbed country in Australia. Until recently, there has been little opportunity for economic development in these areas, but increasingly, Aboriginal people are becoming involved in projects involving pastoralism, tourism, ranger programs (http://www.clc.org.au/OurLand/landmanagement.asp) and the growing native foods industry.

Urban Centre Localities with proportion of Indigenous population

Urban Centre Localities (population > 200 people) showing proportion of Indigenous people and Indigenous communities with < 200 people  Size of circles for the UCLs represent population size classes. Population data from 2001 ABS Census.

The map shows where people living on discrete Indigenous communities travel to their service centres.

Source: Taylor, J 2002, The spatial context of indigenous service delivery, Centre for Aboriginal Economic

Policy Research, The Australian National University, Canberra.

IBRA

The Interim Biogeographic Regionalisation for Australia (IBRA) breaks Australia up into areas based on their natural resources. See Australia's Biogeographical Regions - IBRA - Home page for details.

The IBRA map is © Commonwealth of Australia 2006

SLA

The Statistical Local Area (SLA) is a geographic area of Australia used by the Australia Bureau of Statistics for collection and publication of Census data. © Commonwealth of Australia 2001

The well vegetated landscapes of inland Australia challenge popular views of deserts as ‘wastelands’. Most Australians do not choose to live in Australia’s dry interior but there are large communities in these remote areas.   Australia’s deserts are home to 500,000 people with 20% comprising a growing and diverse Indigenous population.

Pastoral stations occupy a large sector of the this area and pastoralism is the most extensive industry. Aboriginal lands currently compromise about 20% of arid Australia, conservation or national parks about 4% and crown land about 15%. Tourism and mining have primary control over smaller areas, but are important economically, as are other small-scale diversifications such as commercial horticulture.

Visit the National Land and Water Resources Audit website (http://www.nlwra.gov.au/) to download the most current version of the data.

 
Primary code pdf 197 kb

 
Secondary code pdf 840kb

 
Tertiary code pdf 215 kb

Land use mapping shows where resources are being used for the production of goods and services. (Australian Government Department of Agriculture, Fisheries and Forestry - mapping). The most extensive form of land use in the arid zone is pastoralism. Most of this land is leased by the government to pastoralists who graze sheep and/or cattle. Pastoralists obtain a financial benefit from the use of land and in exchange, pastoralists produce food and wool, and assist in the management of feral animals, vegetation change and fire over these vast areas. Most of the arid zone is too dry for agricultural production such as cropping.

A large section of the arid zone is comprised of Aboriginal owned land. A range of land uses occur within these lands, including traditional hunting and gathering, pastoralism, mining, conservation and tourism (http://www.clc.org.au/media/publications/rose_reports/intro.asp)

Mining takes up only a small amount of area in the arid zone, but represents a large contribution to the economy. Often, small towns are established especially to service a mining area, which may produce minerals such as iron ore, nickel gold and base metals. The exploration activity associated with mining can impact on large areas of land can have detrimental effects on the natural environment.

Tourism is also a major industry in desert Australia, and many regions rely on it for economic security. Many tourists are attracted by the natural features of the landscape, so the most visited areas are often National Parks or nature reserves. These areas need to be carefully managed as the high level of tourist activity can put pressure on the natural environment.

The maps displayed here show land use at three different level of detail. The primary code shows land use at its most basic form. The tertiary breaks the land uses down to more specific forms. The secondary code falls between the other two codes.

Major Rivers

Due to the low level of rainfall in the arid zone, the rivers and drainage lines are often dry and only flow intermittently after significant rainfall events. When they do flow, the water will eventually either flood out into the open flat country or salt pans or soak into the sand. Water becomes trapped beneath the sand, still providing moisture to plants and animals during dry times.

Vegetation groups

Deserts in Australia are permanently covered in vegetation. The plants have evolved to conserve and efficiently use any water that becomes available to them. The most common communities in the desert are mulga shrublands, Mallee woodlands, tussock grasslands, Spinifex grasslands, Hummock grasslands, saltbush and bluebush. The type and distribution of the vegetation is determined by the soil and amount of rainfall.

This map shows the range of vegetation communities found in Australia based on growth form, showing the tallest stratum. In desert areas this stratum is principally low trees, shrub and grassland.

Soil Groups

The soils of central Australia are generally very old, shallow, fragile and low in nutrients. The fragile nature of the soil makes the land more susceptible to erosion and degradation from poor land management practices (http://www.nt.gov.au/nreta/naturalresources/soil/faq.html). 

The map shown here is based on soil properties that affect land management.

The most common soil types found in desert Australia on this map is the Cf mapping unit that includes shallow sand soils, shallow loam soils, shallow clay soils and predominately bare rock.

Bureau of Rural Sciences (1992). Interpretations of the Digital Atlas of Australian Soils mapping units (ARC/INFO® format). [Online] Available HTML: http://www.brs.gov.au/data/datasets

Digital Atlas of Australian Soils - Metadata has detailed soil maps available for download.