MASTER THESIS ENHANCING EARLY WARNING SYSTEM IN THE UPPER BEKASI WATERSHED THROUGH THE EMPLOYMENT OF HYDROMETEOROLOGICAL MODEL Nizam Mawardi S2454033 MASTER OF ENVIRONMENTAL & ENERGY MANAGEMENT Dr. Kris Lulofs Dr. Gül Özerol Prof. Chay Asdak 2020/2021 ABSTRACT Hydrometeorological disasters often occur around the world, including floods due to overflowing rivers. One of them is the flood in urban areas in the Upper Bekasi watershed, West Java Province, Indonesia. The selected flood-prone area is located between two tributaries, namely the Cileungsi river and the Cikeas river. Early warning systems were established to reduce the risk of flooding. However, the flood incident due to heavy rain that lasted for a long time on 1 January 2020 was classified as very severe and caused significant damages. To improve preparedness, this study uses a new hydrometeorological model, WRF-Hydro. This study aims to provide insight into the existing early warning in the study area, analyze the response to actions taken by the community and local disaster management agencies, and test WRF-Hydro's ability to simulate torrential rain. This study uses an exploratory approach to describe the early warning system that existed and an experimental approach to test the model's capabilities. This study shows how WRF-Hydro can be optimized for use by competent authorities to improve the flood early warning system. ii ACKNOWLEDGMENTS First and utmost, all praise is to Allah for the blessing to accomplish this thesis throughout difficult situations. I would like to thank my supervisor Dr. Kris Lulofs for relentlessly supporting and providing me with his knowledge and generosity throughout the development of this thesis. I would also like to express my gratitude to my supervisor committee, Dr. Gül Özerol and Prof. Chay Asdak, for constant guidance. I would like to thank Beasiswa Pusbindiklatren Bappenas, BMKG, and MIL Unpad for giving me this excellent opportunity to study at the University of Twente. I would also like to thank you, MEEM students and staff, for the friendship and hospitality. Last but not least, I would also like to thank my family, whom I love the most, for their unwavering support. iii TABLE OF CONTENTS ABSTRACT ............................................................................................................................ ii ACKNOWLEDGMENTS ........................................................................................................ iii TABLE OF CONTENTS ...........................................................................................................iv LIST OF ABBREVIATIONS .....................................................................................................vi LIST OF FIGURES ................................................................................................................. vii LIST OF TABLES .................................................................................................................. viii CHAPTER I Introudction ...................................................................................................... 1 1.1. Background .............................................................................................................. 1 1.2. Problem Statement .................................................................................................. 4 1.3. Research Objective .................................................................................................. 5 1.4. Research Questions ................................................................................................. 5 1.5. Thesis Outline ........................................................................................................... 5 CHAPTER II Literature Review ............................................................................................. 6 2.1. Extreme Rainfall ....................................................................................................... 6 2.2. Urban Hydrometeorology ........................................................................................ 7 2.3. The Elements of Early Warning and Flood Forecast ................................................ 8 2.4. Early Warning Systems as Decision-making Tools ................................................. 10 2.5. WRF and WRF-Hydro ............................................................................................. 10 2.6. The Employment of WRF/WRF-Hydro ................................................................... 12 CHAPTER III Research Design ............................................................................................ 14 3.1. Research Framework ............................................................................................. 14 3.2. Research Strategy .................................................................................................. 16 3.2.1. Running the Conventional WRF and WRF/WRF-Hydro .................................. 16 3.2.2. Output Data Analysis and Verification ............................................................ 17 3.2.3. Research Boundaries....................................................................................... 18 3.2.4. Research Unit .................................................................................................. 18 3.2.5. Selection of Research Unit .............................................................................. 18 3.3. Data Collection ....................................................................................................... 19 3.4. Data Analysis .......................................................................................................... 20 3.5. Ethics Statement .................................................................................................... 21 CHAPTER IV Results and Discussion .................................................................................. 18 4.1. Background Information about the Flood-Plain .................................................... 18 iv 4.1.1. The Profiles of Cileungsi and Cikeas Watersheds ........................................... 18 4.1.2. Administrative Areas between Watersheds ................................................... 20 4.1.3. Flood Prone Areas ........................................................................................... 23 4.2. Flood Risks and Costs ............................................................................................. 24 4.3. Flood Preparedness and Response Actions ........................................................... 26 4.3.1. Extreme Weather Early Warnings ................................................................... 26 4.3.2. Flood Early Warnings ...................................................................................... 28 4.3.3. Flood Response Actions .................................................................................. 33 4.4. Meteorological Analysis ......................................................................................... 36 4.5. Model Output Comparison .................................................................................... 40 4.6. Best Use of WRF-Hydro .......................................................................................... 43 4.7. Discussion ............................................................................................................... 48 CHAPTER V Conclusions .................................................................................................... 51 5.1. Answers to Research Questions ............................................................................ 51 5.2. Directions for Future Research .............................................................................. 52 References ........................................................................................................................ 53 Appendices ........................................................................................................................ 65 Appendix A. Total Area and Demographics of Bogor Regency ..................................... 65 Appendix B. Questionnaire ........................................................................................... 66 Appendix C. Two Versions of Consent Form ................................................................. 69 v LIST OF ABBREVIATIONS BMKG Indonesian Agency for Meteorology, Climatology, and Geophysics BNPB Indonesian National Agency for Disaster Management BPBD Regional Agency for Disaster Management BBWSCC Centre for Ciliwung-Cisadane River Basin GFS Global Forecasting System GSMaP Global Satellite Mapping of Precipitation GWP Global Water Partnership IMC Indonesian Maritime Continent KP2C Cileungsi-Cikeas River Care Community NMHSs National Meteorological and Hydrological Services NOAA National Oceanic and Atmospheric Administration NWM National Water Model NWS National Weather Service PCC Pearson’s Correlation Coefficient RMSE Root Mean Square Error TRMM Tropical Rainfall Measuring Measure WMO World Meteorological Organization WRF Weather Research and Forecasting vi LIST OF FIGURES Figure 1 Percentage of Natural Disaster Events in Indonesia between 2000 and 2020 .... 1 Figure 2 The Confluence of Cileungsi River and CIkeas River ............................................. 4 Figure 3 WRF Components ............................................................................................... 11 Figure 4 Research Framework