Studi Pendahuluan Pemisahan Aliran Dasar Menggunakan "Metode Grafis dan Filter" di

Abstract

This study dealt with estimation of baseflow at severals watersheds in the area of UPT PSDA Bondowoso (Eastern part of East Java, Indonesia). Eigth watersheds were selected for this study. Two graphical methods of baseflow separation (Fixed Interval Method and Local Minimum Method) and Eckhardt filter were used to separated baseflow from total flow. Eckhardt filter was one of the Recursive Digital Filter (RDF) method of baseflow separation. Methodology consist of : (1) data inventoring (2) data processing, (3) calibrating and validating, and (4) model performances evaluating. Daily discharge were used as main input for the analysis. Then, one RDF method and two grapichal methods were used to separate baseflow from the total daily discharge. Furthermore, each algorithm was calibrate using daily discharge data for each year. The mean values of parameters obtained ware then used to separate baseflow for whole periode of record. RMSE and Scatter plot are used to evaluate the model performance during dry periode (Juli to September) assuming that for this period no rainfall have occurred. Calibration were conducted with the same prosedure. Validation was conducted from watershed with more complete data (Kloposawit watershed). This Study showed that Fixed Interval method perform better than two others methods.