Studi Pemisahan Baseflow menggunakan Metode Grafis dan Metode Recursive Digital Filter

Abstract

Technique baseflow separation can be performed by graphics and Recursive Digital Filter (RDF) methods. This research was conducted in to estimate the baseflow contribution at seven watersheds in administratif UPT PSDA Lumajang – Eastern part of East Java. Two graphical methods of baseflow separation (Local Minimum Method dan Fixed Interval Method) and Eckhardt filter were compared to separated baseflow from total flow. Eckhardt filter of the Recursive Digital Filter (RDF) method of baseflow separation.. Methodology consist of : (1) data inventorying (2) data processing, (3) calibrating and validating, and (4) models performances evaluating. Daily discharge were used as main input for the analysis 1996-2005. Furthermore, each algorithm was calibrate using daily discharge data for each year. The mean values of parameters obtained used to separate baseflow for whole period of record. RMSE, R Squared and FDC used to evaluate the model performance during dry periode (Juli to September – with assumtion that there was no rainfall occurred in this period). Calibration was conducted on each watershed with the same technique. Validation was conducted using parameter values obtained from watershed having more complete data (Rawatamtu watershed) to others watersheds. The results showed that Local Minimum Method perform better then others algorithms.