INFLUENCE OF BASEFLOW ON FLOODS IN JAKARTA, CASE STUDY OF CILIWUNG RIVER WATERSHED

• Main Author: Janitra Priyasmara, Dovan
• Format: Theses
• Language: Indonesia
• Subjects: Teknik (Rekayasa, enjinering dan kegiatan berkaitan)
• Online Access: https://digilib.itb.ac.id/gdl/view/77156
• Institution: Institut Teknologi Bandung

This research uses recursive digital filters for digital signal processing and system analysis. This filter applies repeated mathematical functions to the previous input and output signals. By using recursive filters, digital signals can be processed and filtered more flexibly and information from previous time steps can be integrated in filtering process. Determination of the optimum alpha (?) was carried out in the dry months of June, July, August, September. The two methods tested were Lyne & Hollick and EWMA with the tested alpha ranges of 0.9 - 0.99 and 0.003 - 0.015 respectively. The most suitable method used after testing the performance of RSME and R2 was Lyne & Hollick with an alpha of 0.9. The optimum alpha value obtained was used for baseflow separation in the specified flood event and then with the hydrograph method to obtain the value of direct runoff, baseflow and total runoff. In the 2009, 2013, 2014 and 2020 flood events in Jakarta, it was found that the January 2009 flood event had the smallest contribution of baseflow volume in one flood event, which was 3,538,913.27 m3 (52.17% of the total water runoff volume). Meanwhile, the highest contribution of baseflow volume to a single flood event occurred in January 2013 with 62,964,435.33 m3 (85.76% of total water runoff volume). The percentage of baseflow in the studied flood events ranged from 52.17% to 85.76%. This finding indicates that baseflow from the upper Ciliwung Watershed has a significant contribution to flooding in Jakarta.