Derivation of S-Curve from Oscillatory Hydrograph Using Digital Filter

An oscillatory S-curve causes unexpected fluctuations in a unit hydrograph (UH) of desired duration or an instantaneous UH (IUH) that may affect the constraints for hydrologic stability. On other hand, Savitzky–Golay smoothing and differentiation filter (SG filter) is digital known to smooth data without distorting signal tendency. The present study proposes method based on SG cope with S-curves. Compared previous conventional methods, application was shown drastically reduce oscillation problems IUH. In this method, parameters are selected give minimum influence differentiation. Based runoff reproduction results performance criteria, it appears performed both remarkable variation properties such as peak time-to peak. IUH, UH, were estimated using storm from two watersheds. reproduced runoffs showed high levels model criteria. addition, analyses watersheds revealed small watershed areas experience scale problems. proposed believed be valuable when error-prone involved analyzing linear rainfall–runoff relationship.