HIGH FLOW AND LOW FLOW FREQUENCY ANALYSIS OF CIKAPUNDUNG RIVER

• Main Author: Suryadi, Cahya
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/39588
• Institution: Institut Teknologi Bandung

Climate change that occurs in Indonesia specifically in the upstream and middle Citarum areas is marked by changes in rainfall which increased by 3.64% for every 100 months. The decrease in rainfall due to a decrease in cloud formation and rain is due to two things, namely forest combustion and global climate variability (Ruminta, 2008). In addition to the phenomenon of climate change, an increase in the number of population that occurs in an area will have an impact on changes in river discharge cover, so it is necessary to study the dominant parameters that cause changes in discharge between changes in rainfall and land cover changes. rain, discharge and land cover, the effect of changes in rainfall and changes to flood cover, maximum and minimum mainstay temporal discharge, duration duration shift curve and discharge percentile change. The results of the analysis that have been conducted found that rainfall data for the last 32 years (1986-2017) tended to increase. Then the trend of daily debit data for the last 13 years (2004-2016) at Maribaya Station and the last 11 years (2004-2014) at Gandok Station from both discharge stations tends to increase, as well as land changes that have increased. The Snyder-Alexejev SUH method obtained the largest NSE value of 0.74 so that it can be categorized as "Good", so to calculate the flood discharge using the Snyder-Alexejev HSS method. The results of the flood discharge analysis for 3 (three) Cikapundung watershed found that changes in flood discharge were dominated by changes in rainfall. The NRECA method can provide better results than the F.J method. Mock, this is indicated by the NSE mean value of 0.95. Maximum mainstay discharge shows a tendency to increase from the monthly 10th daily results, whereas this is inversely proportional to the smaller minimum flow, in 3 Cikapundung sub-watersheds the shift of the FDC Normal Curve in the period 1986-2009 shows a level of change that is quite thin shows a large degree of difference, but the FDC for the period 2009-2017 shows a fairly high change shown by the symptoms of ecosurplus at high flows where this could be an indicator of flooding. In 3 sub-watersheds of Cikapundung the shift of the FDC Logarithmic Curve (1986-1993) and FDC (1993-2001) shows a shift in ecodeficit on dry and low flows, when seen from the FDC shift (1993-2001) and FDC (2001-2009) showing ecodeficit shift on dry flows and shifts in ecosurplus at low flows, while based on the FDC shift (2001-2009) and FDC (2009-2017) shows the opposite condition which shows a shift in ecosurplus on dry flows and ecodeficit shifts at low flows where this can be an indicator of reduced base flow. Changes in high and wet flow percentile discharges in 3 sub-watersheds showed an increase in the period 2009 to 2017, then for changes in middle flow showed the same thing in high and wet flows but there was a slight increase in the period 2009 to 2017, and for dry and low flow changes showed a decline in the period 1986 to 1993 while there was a flat trend in the period 1993 to 2017.