STUDY ON ECOSYSTEM AND WATER QUALITY MAINTENANCE FLOWS IN THE MANAGEMENT OF WATER RESOURCES IN CITARUM RIVER

• Main Author: SITI MARIAH HAPIPAH, LILIS
• Format: Final Project
• Language: Indonesia
• Subjects: Teknik saniter dan perkotaan; teknik perlindungan lingkungan
• Online Access: https://digilib.itb.ac.id/gdl/view/61271
• Institution: Institut Teknologi Bandung

Population growth in the Citarum River Basin leads to an increase in water demand for various human needs such as domestic, agriculture, industry, and energy. With the implementation of Integrated Water Resources Management (IWRM), it is necessary to allocate environmental flow requirements as Ecosystem and Water Quality Maintenance Flows. Determination of such flows in this study using the daily streamflow data of Nanjung Station in 1974-2019 (analysis period) with the hydrological methods consisting of Q95, 7Q10, Tennant Method, Tessman Method, and Global Environmental Flow Calculator (GEFC) software. The study results shows that GEFC Class D allocates an average flow of 26.31 m3/s (33.5% of MAF). The discharges from Q95, 7Q10, and the Tennant Method (fair/degrading) are below Class D so they are not reliable for maintaining ecosystem in the Citarum River. Tessman Method allocates an average of 37.53 m3/s (47.79% of MAF), but it is too high for the Citarum River which is located in a densely populated area. Daily streamflow data series in 1919-1935 (base period) is used to compare hydrological conditions. Analysis of the flow regime through the magnitude, variability, and time of flows occurrence, shows that there is hydrologic alteration from the base period to the analysis period, with the increasing of Mean Annual Flow (68.21 m3/s to 78.53 m3/s) and the coefficient of variation (0.205 to 0.378), as well as changes in the number of months for high flow (6 months to 7 months) and low flow (3 months to 2 months). Hydrological changes are then associated with El Niño and Southern Oscillation (ENSO) and land use/land cover changes. Pearson Correlation Coefficient and significance two-tailed t-test (? = 5%) is used to test the relationship between Citarum River flows and ENSO index in the form of Sea Surface Temperature Anomaly (SSTA) Niño 3.4, with the result that there is a significant correlation between the two test variables for the analysis period data, due to changes in ENSO behaviour since the mid-1970s. Land use/land cover changes in the Upper Citarum River Basin that occurred between 1990-2016 showed a tendency to decrease in primary forest area and increase in urban or built-up area that affect surface runoff.