A Standard Approach to Baseflow Separation Using The Lyne and Hollick Filter

The digital filtering approach to baseflow separation suggested by Lyne & Hollick (1979) has been widely used and is available in a number of computer packages. However, details of the approach used by different authors vary and so do the results. This means baseflow volumes and indices reported by different authors, and at different times, are difficult to compare. We propose a standard method for baseflow separation using the Lyne and Hollick digital filter. This includes reflecting the flow series at the start and end of the record to reduce “warm up” effects and the adoption of specific starting values for each filter pass.