Title

Watertable Elevation Surface 

Alternate title

WATERTABLE_ELEVATION_SURFACE 

Supplemental Information

Related Documents: None 

Status

Completed  

Code

4283 

Maintenance and update frequency

As needed  

Title

DIGITAL: ESRI ASCII GRID, ESRI GRID, JEPG2000 2 

Topic category

• Inland waters
• Geoscientific information

Use limitation

General 

Classification

Unclassified  

Statement

Dataset Source: A review was undertaken of such issues as the distribution of available data and existing watertable models, the broad hydrogeological systems and existing hydrological divisions of the state. Subsequently, it was decided that the watertable model would be compiled as a series of sub areas approximately reflecting the geometry of the Catchment Management Authority Areas (CMA). Compilation of the watertable geometry utilised three main methodologies. The first method involved those CMAs south of the divide in the Southern Rural Water (SRW) area. The watertable geometry from a previous SRW project was adopted. This was modified in some areas as explained later for each CMA. The second involved a terrain analysis technique based on the premise that the watertable is a smoothed and subdued reflection of topography. This technique is best used in regions of sparse bore data and complex topography/watertable. It is less suitable for plains regions with little topographic relief and where there tends to be the highest concentration of bore data. Within the basement areas of the watertable aquifer the result of this analysis was adopted as the watertable model. The third method involved using the available bore data and the output from the second method as input to the surface modelling utility ANUDEM. ANUDEM is a program that calculates regular grid digital elevation models with sensible shape and drainage structure from arbitrarily large data sets. While traditionally used to create terrain models, ANUDEM is ideally suited for compiling any surface that has significant direction or flow control such as groundwater geometry. ANUDEM was used to compile the watertable geometry over the plains and other non basement areas. For those CMA areas north of the divide a combination of methods two and three were adopted. The resultant watertable surface for each CMA was then validated against the bore data. Differences between the surface and the bore data have three main causes. (1) The surface compiled from the bore data (as per the southern CMA and basement areas); (2) The 27 year temporal range of the data resulting in an average surface being created; (3) The positional accuracy of the bore location making a comparison not valid. Dataset Originality: Derived 

Classification

Unclassified  

Attribute Quality

Comments

Not known and has not been assessed. 

Positional Accuracy

Comments

This dataset has been derived from datasets of varying and not always known accuracy. 

Conceptual Consistency

Comments

Not known. 

Missing Data

Comments

Victoria 

Excess Data