Abstract:
Understanding of the runoff generation processes is important in understanding the magnitude and dynamics of
groundwater discharge. However, these processes continue to be difficult to quantify and conceptualize. In this study,
two digital filter based separation modules, the Recursive filtering method (RDF) and a generalization of the
recursive digital filter (GRDF) were1991–2002 in the Hableh Roud River at the stream gauge of Bonkuh, Semnan
province. A technique for assessing the recession constants of the sub flows based on calibration the average value of
the inverse of the value of the inverse of the slope of the linear path in the recession periods of an Ln (q)-time graph
is presented. The result show that, the GRDF method gave higher (Baseflow index) BFI values than the RDF method
with less variability and the mean baseflow calculated on an annual basis, ranged from 3.27 m3/s to 4.04 m3/s over
period of study by RDF and GRDF, respectively. Since the true values of the baseflow index are unknown, it cannot
be said, which one of the methods gives the best estimates.
Machine summary:
In this study, two digital filter based separation modules, the Recursive filtering method (RDF) and a generalization of the recursive digital filter (GRDF) were1991–2002 in the Hableh Roud River at the stream gauge of Bonkuh, Semnan province.
The result show that, the GRDF method gave higher (Baseflow index) BFI values than the RDF methodwith less variability and the mean baseflow calculated on an annual basis, ranged from 3.
Baseflow separation from streamflow hydrographs has long been a topic interest in hydrology (see, Hall, 1968; Birtles, 1978; Tallaksen, 1995; Chapman, 1999; Arnold and Allen, 1999; Piggot et al.
The other is those that account for the effects of bank storage and assume that the baseflow recession continues after the time when surface runoff begins (Nathan and McMahon, 1990) (curve a–d–e–c in Fig. 1).
However, tracer based methods may not be practical and economic in the long run and it is not possible to apply them to past discharge time series if no chemical/isotopic data of stream water and main source areas are available, which is usually the case.
The baseflow component of the streamflow time series can also be separated using data processing or filtering procedures.
In the present study, we compared baseflow indices that are mathematical filters by the methods of the Arnold and Allen (1999) and Willems (2009) which have been implemented in BFLOW and WETSPRO program respectively.
A physically based filter for separating baseflow from streamflow time series.