Automated Methods for Estimating Baseflow from Streamflow Records in a Semi Arid Watershed

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.