Precision Ag

These images are from version four of CGIAR-CSI's Shuttle Radar Topography Mission elevation data. Each image corresponds to a 'tile', and the biggest is about 6MB. The legend has been chosen for the Wimmera/Mallee, but extended at the top and bottom end to cover the other less important bits of south eastern Australia. Click on an image to download the corresponding tile:

For those seeking the broader view of gamma-radiometrics for the south east of Australia, these Google Earth images are for Minty (2009)'s  Radiometric map of Australia (First Edition):

The legends are, where possible, the same as for the Victorian data.

South Australian Mallee/Riverland users need to be wary of a large area of poor data quality along the Sunraysia Hwy to Nuriootpa, and along the Mallee Hwy to Peake. There is an outline of the area here. There seems to be some data, but it must have been taken at wider spacing (less precise).

A drawback (at present) of the data download page at www.malleefocus.com.au/data is that you can't easily see the 'big picture' of the data. I've had to develop some images of the Shuttle elevation and GeoSciences Victoria gamma-radiometrics data for some work on the BCG/Vic No Till Flexible Farming Project. These images may be useful for people trying to understand what variation at the farm level might mean. 

I've put the images into Google Earth '.kmz' files. These are the links to the images. Those on slow connections need to beware: some kmz files are up to 10Mb and will take a while to download:

  The images illustrate some of the features that make the gamma-radiometrics data useful, and also the east-west artifacts that users south of Swan Hill and east of Birchip need to be careful of. 

Soils around rivers and lakes have much in common with soils on hills to the south-east. The 'fingers' of soil blown in from South Australia's coast can be seen to be mixed in to some of the areas around them. The 'plains' of the southern Mallee and northern Wimmera are somewhere between.

The elevation data shows clearly the outline of the ancient Lake Bungunnia, below about 65m, and the possible past course of the Murray river along the now Wimmera river.  'Strand lines' (beach dunes) of the retreating Murrayvian gulf and lunettes of ancient lakes can also be distinguished from the dunes that are more obvious at ground level.

I'm not sure how to interpret the magnetics. It's supposed to relate to depth to bedrock. It does show that there's some weird things going on, centered on Culgoa and from Horsham northwest to Murrayville. 

If you would like to share an observation on the data and what you think it means, please post a comment! 

This is an example of what you will see in Google Earth, in this case the elevation image over the Tyrrell basin (it's upside-down - I was looking from the north):

I’ve been working (with Mallee CMA) on a web page that allows farmers to download publicly available spatial data: www.malleefocus.com.au/data

It’s been through various phases of testing and seems to work OK.

The aim of the page is to give Wimmera and Mallee farmers free access to some spatial data that will help them make variable rate/zoning decisions in time for sowing 2009, especially if they don’t have other sources such as yield maps or EM38 surveys. There are some good sources of spatial data out there – DSE have elevation on a 10 x 10m grid that covers the whole of the state, and GeoSciences Victoria have gamma-radiometrics on a 50 x 50m grid. They are publicly available but have been difficult for farmers to get and process in the past.

The web page allows farmers to draw their property on a Google map. After filling in a few details they will then receive an email containing ‘shapefiles’ of data for that area. The shapefiles can be opened in precision agriculture software such as SMS, Case AFS, John Deere’s Apex, and free GIS programs such as MapWindow. The elevation data will help to sort hills, flats and low spots. The gamma-radiometrics data relates to the parent material of the top 30cm of soil and may be useful for understanding soil variation in some areas.   

The work has been a ‘love job’ and farmers may have to be patient if the emails take a day or two to come through. I’d also be keen to have feedback on the site if anyone has ideas on how it could be improved. There is some data there for SA and NSW and I will add new data as I become aware of it. If you come across any, please email!