This document is downloaded from DR‑NTU (https://dr.ntu.edu.sg) Nanyang Technological University, Singapore. Ensemble flood forecasting by neuro‑fuzzy inferencing Yu, Lan 2016 Yu, L. (2016). Ensemble flood forecasting by neuro‑fuzzy inferencing. Doctoral thesis, Nanyang Technological University, Singapore. https://hdl.handle.net/10356/68924 https://doi.org/10.32657/10356/68924 Downloaded on 02 Oct 2021 09:35:39 SGT ENSEMBLE FLOOD FORECASTING BY NEURO- FUZZY INFERENCING YU LAN School of Civil and Environmental Engineering 2015 1 ENSEMBLE FLOOD FORECASTING BY NEURO-FUZZY INFERENCING YU LAN School of Civil and Environmental Engineering A thesis submitted to the Nanyang Technological University in fulfillment of the requirement for the degree of Doctor of Philosophy 2015 ACKNOWLEDGEMENTS I would like to take this opportunity to express my gratitude to those people who support me during my four-year research and life. I want to thank my first advisor, Associate Prof Lloyd Chua, who offered me the research opportunity into the interesting world of modeling. Professional advice, continuous support and insightful comments that he gave to me helped me get through those challenges in my research study. I would also like to thank my supervisor, Associate Prof Tan Soon Keat, for helping me in my last two years of PhD research. His patience, immense knowledge and precious support helped me to finalize my PhD research. The measured data and URBS results from Chapter 4- 5 were generously provided by the Mekong River Commission. The funding for the work from Chapter 6-7 was provided by the DHI-NTU Centre, NEWRI and National Chung Hsing University. I also wish to thank the TTFRI for providing data for this research. I would like to thank Amin Talei for his professional suggestions in modeling and helping me get out of the confusion in my research. I want to thank my family for giving me the constant and tremendous energy in my work and life. I want to thank Wang Qi, who went from being my girlfriend to my wife in my PhD life, for your love. Last but not least, I would like to thank all my lovely friends in Singapore. Their company makes a piece of precious memory in my PhD life. I TABLE OF CONTENTS ACKNOWLEDGEMENTS ..................................................................................... I SUMMARY ……………………………………………………………………..VI LIST OF TABLES ............................................................................................... VIII LIST OF FIGURES ............................................................................................... IX LIST OF ABBREVIATIONS .............................................................................. XII LIST OF PUBLICATIONS ................................................................................ XIV CHAPTER 1 INTRODUCTION ........................................................................... 1 1.1 BACKGROUND ............................................................................................... 1 1.2 MOTIVATION ................................................................................................. 2 1.3 OBJECTIVES .................................................................................................. 3 1.4 SCOPE ........................................................................................................... 4 CHAPTER 2 LITERATURE REVIEW ............................................................... 6 2.1 INTRODUCTION ............................................................................................. 6 2.2 FLOOD FORECASTING ................................................................................... 6 2.2.1 Physically Based Models ...................................................................... 6 2.2.2 Statistical Models ................................................................................ 12 2.2.3 Data-Driven Models ............................................................................ 18 2.3 ENSEMBLE METHODS ................................................................................. 24 2.3.1 Ensemble Methods in Weather Forecasting ........................................ 24 2.3.2 Ensemble Methods for Optimization in Water Resources .................. 26 2.3.3 Ensemble Methods in Flood Forecasting ............................................ 26 CHAPTER 3 METHODOLOGY AND DATA USED ....................................... 32 3.1 INTRODUCTION ........................................................................................... 32 II 3.2 SIMPLE AVERAGE METHOD ......................................................................... 32 3.3 ADAPTIVE-NETWORK-BASED FUZZY INFERENCE SYSTEM.......................... 33 3.4 DYNAMIC EVOLVING NEURAL-FUZZY INFERENCE SYSTEM ........................ 35 3.5 STUDY AREAS ............................................................................................. 37 3.5.1 Lower Mekong Basin .......................................................................... 38 3.5.2 Lanyang Creek Basin, Taiwan ............................................................ 39 3.6 ERROR ANALYSIS ........................................................................................ 42 CHAPTER 4 WATER LEVEL FORECASTING FOR THE LOWER MEKONG USING A NEURO-FUZZY INFERENCE SYSTEM ENSEMBLE APPROACH 46 4.1 INTRODUCTION ........................................................................................... 46 4.2 METHODOLOGY .......................................................................................... 47 4.2.1 ANFIS Ensemble Model (ANFIS-EN) ............................................... 47 4.2.2 DENFIS Ensemble Model (DENFIS-EN) .......................................... 49 4.2.3 Data Used ............................................................................................ 49 4.3 RESULTS AND DISCUSSIONS ........................................................................ 52 4.3.1 ANFIS Ensemble Model ..................................................................... 52 4.3.2 DENFIS Ensemble Model .................................................................. 56 4.3.3 Analysis of Results ............................................................................. 59 4.4 CONCLUSIONS ............................................................................................. 63 CHAPTER 5 ONLINE ENSEMBLE MODELING FOR REAL TIME WATER LEVEL FORECASTS FOR THE LOWER MEKONG RIVER ...................... 65 5.1 INTRODUCTION ........................................................................................... 65 5.2 METHODOLOGY .......................................................................................... 66 5.2.1 Neural-fuzzy Model ............................................................................ 66 5.2.2 Real Time Updating Approach ............................................................ 67 5.2.3 Study Site ............................................................................................ 69 III 5.3 RESULTS AND DISCUSSIONS ........................................................................ 70 5.3.1 Offline Ensemble Model (EN-OFF) ................................................... 70 5.3.2 Ensemble Model with Real Time updating using Online Learning (EN- RTON1) ………………………………………………………………………..72 5.3.3 Ensemble Model with Real Time updating using Online Learning and Sub-Models (EN-RTON2) ................................................................................ 77 5.4 CONCLUSIONS ............................................................................................. 81 CHAPTER 6 ENSEMBLE WATER LEVEL FORECASTING FOR LANYANG CREEK, TAIWAN ............................................................................ 83 6.1 INTRODUCTION ........................................................................................... 83 6.2 METHODOLOGY .......................................................................................... 84 6.3 EVALUATION OF INPUT COMPONENT MODELS ............................................. 84 6.3.1 Short- and Long-term Forecasts .......................................................... 84 6.3.2 Forecast Results at Different Water Level Regimes ........................... 89 6.4 RESULTS OF ENSEMBLE FORECASTS ........................................................... 93 6.5 CONCLUSIONS ........................................................................................... 95 CHAPTER 7 ENSEMBLE APPROACH USING MODIFIED OFFLINE MODELS FOR WATER LEVEL FORECASTING IN LANYANG CREEK, TAIWAN ……………………………………………………………………..97 7.1 INTRODUCTION ........................................................................................... 97 7.2 METHODOLOGY .......................................................................................... 97 7.2.1 Modified DENFIS with Linear Constraints ........................................ 97 7.2.2 Modified DENFIS with Linear Constraints and Slopes ..................... 99 7.2.3 Data and Study Area ......................................................................... 101 7.3 RESULTS AND ANALYSIS............................................................................ 102 7.3.1 Results of the Modified Offline Model ............................................. 102 7.3.2 Results of the Modified Offline with Slope Model........................... 109 IV 7.4 CONCLUSION .............................................................................................. 116 CHAPTER 8 CONCLUSIONS AND RECOMMENDATIONS