Water Resource Associates is associated with Chiltern Digitising Services (CDS). Since 1987, CDS has specialized in the conversion of chart-recorded data. Working for every region of the Environment Agency, their bureau service has handled well over 2000 station years of UK water level chart data.
All types of charts (e.g. strip, reversing, curved axes, circular) can be accommodated. The recorded trace may be corrected to observer-annotated readings of time and/or check gauges. The digitised data may be kept ‘as captured’ or subjected to interpolation to any required data interval.
The digitising program used by CDS is called CDIG and has been sold widely in the UK and overseas. It runs with a range of proprietary digitising tablets. The Summasketch Professional III is typical of the lower accuracy devices (+/- 0.25 mm) normally considered adequate for hydrometric data processing although greater precision may sometimes be required.
CDIG enables the recording of comment to ensure that all the information content on a paper chart may be transferred to permanent archive. It also has a ‘replay’ mode where the raw digitised data may be passed through the program again allowing correction of any faulty operator input. It is never necessary to digitise a chart more than once.
CDIG generates output suitable for direct entry to HYDATA, HYDROLOG and WISKI.