Preventive measures for coastal erosion in cua lo, tam quang commune, nui thanh district, quang nam province

MINISTRY OF EDUCATION AND TRAINING MINISTRY OF AGRICULTURE AND RURAL DEVELOPMENT THUY LOI UNIVERSITY HOANG THI LINH GIANG PREVENTIVE MEASURES FOR COASTAL EROSION IN CUA LO, TAM QUANG COMMUNE, NUI THANH DISTRICT, QUANG NAM PROVINCE MASTER THESIS HANOI, 2016 MINISTRY OF EDUCATION AND TRAINING MINISTRY OF AGRICULTURE AND RURAL DEVELOPMENT THUY LOI UNIVERSITY HOANG THI LINH GIANG PREVENTIVE MEASURES FOR COASTAL EROSION IN CUA LO, TAM QUANG COMMUNE, NUI THANH DISTRICT, QUANG NAM PROVINCE Major: Code : Coastal Engineering and Management 62580203 MASTER THESIS SUPERVISOR: ASSOC PROF DR MAI VAN CONG HANOI, 2016 i DECLARATION I hereby certify the work which is being presented in this thesis entitled, “Preventive measures for coastal erosion in Cua Lo, Tam Quang commune, Nui Thanh District, Quang Nam province.” in partial fulfillment of the requirement for the award of the Master of Coastal Engineering and Management, is an authentic record of my own work carried out under supervision of Assoc Prof Dr Mai Van Cong The matter embodied in this thesis has been submitted to UNDP in Vietnam and DMC under the framework of the project “Strengthening Institutional Capacity for Disaster Risk Management in Viet Nam Including Climate Change Related Risks (SCDM Phase II)” Ha Noi, December, 2016 Hoang Thi Linh Giang ii ACKNOWLEDGEMENTS First of all I would like to acknowledge the sponsors UNDP in Vietnam and DMC under the framework of project “Strengthening Institutional Capacity for Disaster Risk Management in Viet Nam Including Climate Change Related Risks (SCDM Phase II)” for the scholarship support I owe special words of many thanks to Assoc Prof Dr Mai Van Cong- my supervisor for his concern, guidance, enthusiasm, valuable advice and assistance with so much care I would like to acknowledge Assoc Prof Dr Tran Thanh Tung and Prof Dr Thieu Quang Tuan who are main co-ordinator of this master program, making value contributions to success in Master course I would like to say thanks to Professor Marcel Stive for his comment on proposed solutions I also want to thank to M.Sc Nguyen Quang Duc Anh from VINWATER for his comments, supports in modeling work and suggestion, M.Sc Le Duc Dung from VASI for his supports in data and model validation I would like to thanks faculty of Marine and Coastal Engineering of Thuy Loi University for providing support in numerous aspects amid the study My high appreciation goes to all the lecturers who have taught and provided me with such valuable knowledge to my future career both in Vietnam and in the Netherland; my colleagues, friends and my classmates for their support and assistance Finally, I would like to keep the great thanks to my sweet family for their great support and always being source of encouragement, motivation and energy iii TABLE OF CONTENTS DECLARATION i ACKNOWLEDGEMENTS ii TABLE OF CONTENTS iii LIST OF FIGURES vi LIST OF TABLES ix INTRODUCTION 1 Rationale of this research Research objectives Focus area Research methodology and implementation Structure of the thesis .2 CHAPTER I: LITERATURE REVIEW 1.1.Overview of erosion and sedimentation 1.1.1.Some researches in foreign countries 1.1.2.Coastal erosion and shoreline changes researches in Vietnam .5 1.1.3.Recent coastal researches in Quang Nam province .9 1.2.Research method in erosion and sedimentation 12 1.2.1.Method of mapping- remote sensing 12 1.2.2.Questionnaire method 12 1.2.3.Field survey method .13 1.2.4.Modeling method 13 1.2.5.Statistical and synthetic analyzing method 13 CHAPTER II: OVERVIEW OF STUDY AREA .14 2.1.Study area description .14 2.2.Natural conditions 15 2.2.1.Climate condition 15 2.2.1.1.Temperature 15 2.2.1.2.Rainfall regime 15 2.2.1.3.Wind regime .16 2.2.1.4.Wave regime 17 2.2.1.5.Typhoons 19 iv 2.2.1.6.Hydrological regime 20 2.2.2.Geological conditions 22 2.3.Social-economic features 23 2.4.Status of coastal erosion and existing coastal protection measures in study areas 23 2.5.Coastal development 28 CHAPTER III: ANALYSIS OF COASTAL EROSION PROCESS AND SHORELINE CHANGES IN THE STUDY AREA 35 3.1.Causes of coastal erosion in study area 35 3.1.1.Hypothesis 1: Erosion caused by structural properties of the coast 37 3.1.2.Hypothesis 2: Erosion and shoreline changes caused by sea level rise and the extreme boundary conditions of hydrological factors 37 3.1.2.1.Erosion and shoreline changes caused by sea level rise 37 3.1.2.2.Effect of typhoons and storm induced cross-shore erosion 38 3.1.3.Hypothesis 3: Erosion and shoreline changes caused by human activities 41 3.2 Analysis of mechanisms for erosion and shoreline changes in the study area 42 3.2.1 CERC formula 42 3.2.2 Mike model 46 3.2.2.1 Data collection 46 3.2.2.2 Mike 21 model 47 3.2.2.3 Model set up 48 3.2.2.4 Calibration and verification of simulation model 54 3.2.3 Evaluation of the hydrodynamic regime in Cua Lo area 57 3.2.3.1 Hydrodynamic regime of Cua Lo area in winter 58 3.2.3.2 Hydrodynamic regime of Cua Lo area in summer 61 3.2.3.3 Hydrodynamic regime of Cua Lo area in flooding 64 3.2.3.4 Conclusions 66 CHAPTER IV: POSSIBLE ALTERNATIVE COUNTERMEASURES 68 4.1 The common principles of planning countermeasures 68 4.2 Proposed planning countermeasures for study area 68 4.3 Evaluating of planning countermeasures by modeling 77 4.3.1 Extraction locations of the results from Mike 21/3 FM model 77 4.3.2 Hydrodynamic regime and bed level change of Cua Lo area in summer 78 4.3.3 Hydrodynamic regime and bed level change of Cua Lo area in winter 82 v 4.3.4 Hydrodynamic regime and bed level change of Cua Lo area in flooding 86 4.3.5 Evaluation of possible countermeasures .90 CONCLUSIONS AND RECOMMENDATION 94 CONCLUSIONS 94 RECOMMENDATION 95 REFERENCES 96 APPENDIXES 100 Appendix 1: Frequency table in Spring, Summer, Autumn, Winter at Ly Son station… .100 Appendix 2: The result of calibration tidal model 104 Appendix 3: The result of verification tidal model .115 Appendix 4: Comparision of bed level change at sections 122 vi LIST OF FIGURES Fig.2- 1: Study area 14 Fig.2- 2: Wind rose at Ly Son (1985-2012) 17 Fig.2- 3: Wave roses in March, April and May at Ly Son station 18 Fig.2- 4: Wave roses in Jun, July and August at Ly Son station 18 Fig.2- 5: Wave roses in September, October and November at Ly Son station 19 Fig.2- 6: Wave roses in December, January and February at Ly Son station 19 Fig.2- 7: River system 20 Fig.2- 8: Discharge of Truong Giang river in flood season 21 Fig.2- 9: Existing coastal protection measures in Cua Lo area (Nui Thanh) 24 Fig.2- 10: Geo-textile (Internet &Google Earth) 25 Fig.2- 11: Geo-textile was destroyed in the southern of Cua Lo in 12/2013 25 Fig.2- 12: Approximately 30 m of existing revetments was seriously damage 26 Fig.2- 13: Large concrete blocks were capsized off the ground 26 Fig.2- 14: Tam Hai revetment, Nui Thanh district, Quang Nam provinces were destroyed after only a short time in use (Internet &Google Earth) 26 Fig.2- 15: Waterway in Cua Lo river mouth(Internet &Google Earth) 27 Fig.2- 16: Eroded area in Ba Tinh, Nui Thanh, Quang Nam (Internet &Google Earth) 27 Fig.2- 17: Coastal development (Google Earth) 29 Fig.2- 18: Average erosion rate in Cua Lo 30 Fig.2- 19: Average accretion rate in Cua Lo 31 Fig.2- 20: Accretion-erosion in Cua Lo in the period from 1965 to 2014 33 Fig.3- 1: Main causes and factors causing coastal erosion and shoreline changes 36 Fig.3- 2: Historic tracks of storm events in the vicinity of the research site 39 Fig.3- 3: Historic relevant tracks of storm events in the vicinity of the research site 40 Fig.3- 4: Phu Ninh reservoir (Google Earth) 42 Fig.3- 5: Representative cross sections 44 Fig.3- 6: Extend of large domain model 49 Fig.3- 7: Nested detailed (small) model 50 Fig.3- 8: Bathymetry of large model 51 vii Fig.3- 9: Bathymetry of small model 51 Fig.3- 10: Boundary conditions of large model 52 Fig.3- 11: The location of water level measuring stations 54 Fig.3- 12: The calibration result of water level at Son Tra station 55 Fig.3- 13: The calibration result of water level at Cua Dai station .55 Fig.3- 14: The verification result of water level at Cua Dai station 56 Fig.3- 15: The distribution of the characteristic waves of Cua Lo area in winter 58 Fig.3- 16: The distribution of total currents (speed and direction) when tide going up of Cua Lo area in winter 59 Fig.3- 17: The distribution of total currents (speed and direction) when tide going down of Cua Lo area in winter 59 Fig.3- 18: Result extracted points from the model 60 Fig.3- 19: Current velocities at points in winter 60 Fig.3- 20: The distribution of the characteristic waves of Cua Lo area in summer 62 Fig.3- 21: The distribution of total currents (speed and direction) when tide going up of Cua Lo area in summer .62 Fig.3- 22: The distribution of total currents (speed and direction) when tide going down of Cua Lo area in summer 63 Fig.3- 23: Current velocities at points in summer 63 Fig.3- 24: Water level of Cua Lo area in flooding 64 Fig.3- 25: The distribution of total currents (speed and direction) in flooding .65 Fig.3- 26: Current velocities at points in flooding 65 Fig.4- 1: Master plan 71 Fig.4- 2: Dredging for navigation 72 Fig.4- 3: Master plan 74 Fig.4- 4: Extraction locations of the results from Mike 21/3 FM model 77 Fig.4- 5: The distribution of total currents (speed and direction) when tide going up and down in summer of master plan 78 Fig.4- 6: The distribution of total currents (speed and direction) when tide going up and down in summer of master plan 79 Fig.4- 7: Bed level change in summer of master plan 80 ... the work which is being presented in this thesis entitled, ? ?Preventive measures for coastal erosion in Cua Lo, Tam Quang commune, Nui Thanh District, Quang Nam province. ” in partial fulfillment...MINISTRY OF EDUCATION AND TRAINING MINISTRY OF AGRICULTURE AND RURAL DEVELOPMENT THUY LOI UNIVERSITY HOANG THI LINH GIANG PREVENTIVE MEASURES FOR COASTAL EROSION IN CUA LO, TAM QUANG COMMUNE,. .. commune, Nui Thanh District, Quang Nam province Focus area - Focus area of this study is a coastal section around the Cua Lo river mouth, belonging toTam Quang commune, Nui Thanh district within the