Technical note: Hydrograph separation: How physically based is recursive digital filtering?
- University of Applied Sciences Weihenstephan-Triesdorf, Weidenbach, 91746, Germany
Abstract. Recursive digital filtering of hydrographs is a widely used method to identify the groundwater-borne portion of streamflow. In this context, a distinction is often made between physically based and non-physically based algorithms. The algorithm of Furey and Gupta (2001), for example, is counted among the former. In this paper, it is contrasted with the algorithm of Eckhardt (2005). This algorithm represents a whole class of recursive digital filters based on the assumption that the aquifer is a linear reservoir. It is shown that the algorithm of Eckhardt (2005) is not merely a low-pass filter, but that it is largely identical to the aforementioned physically based algorithm of Furey and Gupta (2001). The algorithm of Eckhardt (2005) differs from the algorithm of Furey and Gupta (2001) only in the time delay assumed between precipitation and the exfiltration of groundwater into surface waters, and in the fact that two parameters are combined into one, BFImax. This parameter can thus be interpreted physically and an approach for its calculation emerges.
Status: final response (author comments only)
- CC1: 'Comment on hess-2022-186', Keith Beven, 23 Jun 2022
RC1: 'Comment on hess-2022-186', Anonymous Referee #1, 04 Aug 2022
- AC3: 'Reply on RC1', Klaus Eckhardt, 06 Aug 2022
RC2: 'Comment on hess-2022-186', Anonymous Referee #2, 11 Aug 2022
- AC4: 'Reply on RC2', Klaus Eckhardt, 15 Aug 2022
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