b'Geophysics in the surveysNewsGeological Survey of South Australia: SA Geodata gravity module data update completedThe process of updating the gravityThe format of excel sheets laid out byDEM-GSSA decimal degree module in the SA Government databaseDEM-GSSA for data uploading to theconversion excel sheet.SA Geodata, as flagged in the last issuedatabase includes nine columns. It2. If the given Longitude values were of Preview (216), is now complete. 56includes point number (i.e., station numbercorrupted, Northing and Easting surveys were added to the database andand line number) or station numbervalues were used to calculate new they will soon be visible online. This work,only, Longitude and Latitude in decimaldecimal degree values.which is described in the summary reportdegrees, MGA zone, height accordingColumn 4: Adding the correct zone. The that follows, was largely carried out on ato the Australian Height Datum, heightzone column was missing in a small voluntary basis by Sara Mobasher. Sara isaccording to Australia-wide gravimetricnumber of files and was added in the now about to commence studying for aquasigeoid model (AUSGeoid09), heightformatted files. This information was PhD at Adelaide University. according to Geocentric datum of Australiaextracted from the contractors report.2020 (GDA 2020), observed gravity in Project objective and action items mgals or ms2 and a grid flag (effectivelyColumn 5: Elevation AHD. Almost all raw an indication of the quality of data). files had this information, although it was The project had the following simpleIn order to ensure that the data beingmissing in one file and was calculated by objective: uploaded complies with the DEM-GSSAusing the AUSGeoid09 batch processing Update the geophysical section (gravitystandards, the subsequent methodologytool, which can transform between module) on DEM-GSSA Database (SAwas adopted. Ellipsoidal and AHD heights.Geodata). Column 6: Elevation AUSGeoid09. To achieve this objective the followingMethodology This height was calculated using the action items were addressed: AUSGeoid09 batch processing tool. A At the start of the project, an ArcMapCSV file comprising of Latitude (positive project was initiated, displaying gravityvalue), Longitude, type of height (AHD), 1. Segregating the gravity survey datastations along with the tenementheight, model without any header was folders; identifying which gravityboundaries. The gravity survey datarequired. The output generated has an surveys were already available on thefolders to be uploaded on the databaseAUSGeoid09 height.database, and which surveys werewere then reviewed, one by one. The missing. surveys that were already in CSV fileFor example:2. Ensuring that the missing gravityformat with the minimum required survey data files comply with theinformation were converted intoLatitude Longitude Type ofHeight Model standard format set by DEM forshapefiles and dropped into ArcMap toheightuploading data to the database. cross-check whether they were already on23.567 132.5467 AHD 67 AUS 3. Verifying that survey data new tothe database, or needed to be uploaded.geoid09database was acquired at an exportIf the gravity survey needed to be quality level (or not). uploaded, it was kept in a separate folderColumn 7: Elevation GDA2020. This to prepare and upload to the database inheight was calculated using the Background the last stage of the project. This step wasAUSGeoid2020 batch processing performed for about 200 Excel sheets. tool. A CSV file with Latitude (positive Gravity surveys carried out in Southvalue), Longitude, type of height (AHD) Australia fall in MGA Zones 52, 53 andAfter the data folders were sorted, theand height was required. The output 54. Exploration companies are allotteddata files were formatted according togenerated has a GDA2020 height. tenement numbers for their explorationthe DEM-GSSA standards. The DEM-GSSAPlease note that GDA2020 heights are area. The same piece of land may havestandard comprises nine columns: not currently used for Bouguer Gravity different tenement numbers over acalculations but are added to the period of time, as the tenement numbersColumn 1: The station number or pointdatabase for completeness and potential are revised every time they are re-issued. number. The DEM-GSSA databasefuture-proofing.will give an error if it receives a file Tenement holders are obliged to sharewith more than nine digits in a pointFor example, an input file might look like: all newly-acquired geophysical datanumber.with the SA Government as part of their annual reporting. The file formatColumns 2 and 3: This comprises ofLatitude Longitude Type ofHeightis usually an Excel sheet in comma- Longitude and Latitude. Some of theheightdelimited (*.csv) format, but this formatraw files had challenging Longitude23.567 132.5467 AHD 67may vary from company to company, andand Latitude values, which were some even share the files in a notepadresolved depending on their format: Column 8: Observed gravity. All raw format. The excel sheet usually comprises1. If the Latitude and Longitudefiles, with the exception of one file, had key information, for example acquiredvalues were in degrees, minutesthe observed gravity column in mGals. gravity stations locations, observedand seconds (the desired formatWhere only Bouguer Gravity was given, gravity values, gravity correction values,is in decimal degrees), they wereobserved gravity can be back calculated zone etc. converted using an in-houseto meet the requirements (using an APRIL 2022 PREVIEW 20'