Data accuracy and other considerations.

Data collected at a site may be biased towards a specific requirement. For example, a site may have been designed to measure and record low streamflows with high accuracy and any high flow information that is also recorded may be less accurate. At other sites, stream flow volume may not be important but accurate water levels over particular height ranges may be of interest as part of stream ecosystem monitoring. Many sites have a number of concurrent purposes and it is also common for the purpose of a site to change over time.

The location of a site is often a compromise between accessibility, engineering constraints and technical requirements and as such, the final site may not be completely ideal for the prime purpose. Consequently, site location factors have a significant influence on data quality. Other influences include the method used to measure and record the data, damage to recording equipment during flooding and equipment calibration changes over time. Whilst all data undergoes a thorough validation process prior to reaching the archive, users must be aware of those factors that can effect the usability of the data. For example, streamflow data from a site may be considered to be highly accurate and a good record of the actual events at the site but the data may not represent the complete situation. Other external factors such as water supply extractions or diversions from the stream need to be understood and accounted for before determining the natural runoff for the catchment area.

Information about data quality is provided with Site Reports in two formats:

(1) The Data Period Plot and Data Quality Plot :

This provide a summarised graphical representation of different bands of data quality for each variable.

(2) The Site Information Summary Report :

This provides general information about the site and highlights specific data quality issues within the Site History section of the report, under the headings of ACCURACY and XFACTOR (external factors effecting the data).

More detailed data quality information is available if required and data users are encouraged to contact us to discuss the suitability of data for specific purpose before using it. All data users should also note the Copyright and Disclaimer information.