Is this a soil map?
No, this is a soil-landscape map. Because of the challenges of mapping an area of land as large and diverse as Western Australia, the soil-landscape map unit is based on the estimated proportion of soils and landforms found within large geographic areas, and does not show the individual soils within the map unit. The estimates are based on data collected from each soil survey conducted across the state.
To achieve a good representation of soil types and their locations, NRInfo uses the best estimate of the proportion of soils and their associated landscape position in each map unit, at a level of detail which is dependent on the scale of mapping.
What do the numbers and letters in the map unit symbol mean?
The numbers and letters are part of a mapping classification system used throughout Australia. It is a nested hierarchy, which means that every part of the symbol points to a different level of detail in the mapping.
For example, a map unit symbol may be 224MhMJ and it has 3 parts:
- 224: the first 3 numbers are the code for the soil-landscape zone that the map unit belongs to. The soil-landscape zone is the broadest level of soil-landscape mapping used in Western Australia
- Mh: the next 2 letters are the code for the soil-landscape system, which is a more detailed level of mapping that sits within a soil-landscape zone
- MJ: there may be another 2 letters, or a number and a letter, which is the code for the most detailed level of mapping, the soil-landscape subsystem, which sits within a soil-landscape system.
The map unit 224MhMJ is the Arrowsmith (224) soil-landscape zone, the Mount Horner (Mh) soil-landscape system, and the Munja (MJ) subsystem.
More information on the soil-landscape mapping hierarchy is in Chapter 2.2.4 of Soil-landscape mapping in south-western Australia: an overview of methodology and output (Resource management technical report [RMTR] 280).
Why are the map unit names and symbols different from the original published map?
Many originally published maps pre-date the current Western Australian soil-landscape mapping hierarchy model. Original map unit names and labels, and some linework, had to be altered to create a seamless map across Western Australia. The current nested hierarchy of map units was established to deal with the diverse levels of information resulting from varying scales of mapping. More information on the soil-landscape mapping hierarchy is in Chapter 2.2.4 of Soil-landscape mapping in south-western Australia: an overview of methodology and output (RMTR 280).
Why does this map look different from the map in the original publication?
Many of the original surveys were published decades ago. To create a seamless soil-landscape map of Western Australia in a digital format, some of the originally mapped and described areas had to be altered. Alterations included edge-matching of survey linework, revision of linework to fix errors in the original cartography, improved mapping made possible with new information and from new technology, and improved understanding of different landscapes. NRInfo contains the most up-to-date mapping available.
Why does the linework not match the aerial photograph or digital elevation model (DEM)?
One of our ongoing tasks is to manage the evolution of mapping technology which has progressed from hand-drawn soil maps in the pre-digital era to 3-dimensional digital imagery and GPS coordinated locations. Some linework in older maps may not match layers of information in modern GIS mapping. Also, some areas of land may have changed as a result of natural forces, such as flooding.
Why have the interpretations changed since I last obtained data from DPIRD?
When we work on specific projects around the state, we review mapping and related data for the area. Sometimes we find we need to improve soil or landform quality and element details for a map unit. These alterations can change land capability or land quality ratings, which change the maps' appearance.
What does ‘best available’ soil-landscape mapping mean?
The ‘best available’ soil-landscape mapping in NRInfo is the most up-to-date version at the most detailed level available for Western Australia.
How accurate is the land capability and land quality mapping?
These maps are only a starting point for assessing particular areas of land. Because of the scale of the mapping, on-ground assessments are needed to identify characteristics of the property or parcel of land. Individual areas may perform better or worse than the land capability and land quality maps suggest, depending on seasons, soils and management. There will be some variation within each polygon or mapping unit because soil types, landforms, rainfall and water resources are rarely consistent across an entire area. In some areas, landholders may have amended the original soil type or landform with landfill, imported soil or earthmoving.
For more information on soil-landscape mapping, see Soil-landscape mapping in south-western Australia: an overview of methodology and outputs (RMTR 280).
For more information about soil groups of Western Australia, see Soil groups of Western Australia: a simple guide to the main soils of Western Australia (4th edn) (RMTR 380).
For more information about land capability and land qualities, see Land evaluation standards for land resource mapping: assessing land qualities and determining land capability in south-western Australia (RMTR 298).
For information about the soil-landscape zones of the pastoral region, see Soil-landscapes of Western Australia's rangelands and arid interior (RMTR 313).
What are hydrozones and how do they relate to soil-landscape mapping?
Hydrozones are areas of similar geology, hydrology, soils and landscapes and are used for regional groundwater resource and risk assessment. They are based on the soil-landscape zone mapping; however, there are instances where adjacent soil-landscape zones are differentiated by soil or landform attributes that vary at a finer scale than is required for regional groundwater assessments. Where this occurs, the soil-landscape zones are aggregated within a hydrozone.
For more information on hydrozones and groundwater resource and risk assessment, see Groundwater trend analysis and salinity risk assessment for the south-west agricultural region of Western Australia (RMTR 388).
Did we answer your question?
If not, contact us on Soil.Maps@agric.wa.gov.au or the contact below.