Relationship between extreme rainfall and design flood-discharge of the Ciliwung river

Abstract

Abstract Flood in Jakarta is occurred almost every year due to inadequate flood control systems to the flood prediction, inadequate drainage system, and trash that clog the drainage. The increase of rainfall is also one of the causes of flooding. That changing rainfall characteristics can affect river flow. This study aims to analyze the trend of rainfall in different time frames and its effect to flood discharge. The extreme rainfall trend is analyzed for every 15 years period from rainfall data of 1985 to 2019 for several return periods. Three period is selected for trend analysis and compared to the baseline data (1985-2019). Based on the analysis, the extreme rainfall for 1995-2009 and 2005-2019 period compared to the baseline is increased for all return periods. The increasing percentage is approximately 3-10% and 5-16% respectively. Since the extreme rainfall is increased, the design discharge is also increased for all return periods. The increasing percentage for 1995-2009 and 2005-2019 period compared to the baseline is 4-12% and 7-19% respectively. However, the design rainfall and discharge for the period 1985-1999 is lower than the baseline.