Declaration I hereby certify the work which is being presented in this thesis entitled “Modeling storm surge for the South Central Coast of Vietnam” is an authentic record of my own work carried out under supervision of Dr. Vu Thi Thu Thuy and Co-supervisor Ass. Nghiem Tien Lam. The master embodied in this thesis has not been submitted by me for the award of any other degree or diploma.
Date: Aug 15, 2016 Author Ninh Duy Quynh Acknowledgements 1 would like to express my sincere gratitude to my advisor Dr, Vu Thi Thu Thuy and Co-supervisor A/Prof. Nghiem Tien Lam for their guidance, suggestion and inspiration, 1 would like to express my sincere thanks to Thuy Loi University, professors and lectures at Department of Marine and Coastal Engineering of Thuy Loi University and professors and lecturers of the Niche programmer for supporting me throughout study progress, ‘nally, 1 would like to express my special appreciation to my friends and colleagues for their support, encourage and advices. Thank you so much! LIST OF FIGUES. LIST OF TABLES INTRODUCTION 1.
Problem identification and the necessity of the study 2.1 International researches on storm surge 2.2 Past studies on storm surges in Vietnam 3. The scope ofresearch 4, Approach and methodology 5. Thesis structure CHAPTER 1: PHYSICAL SETTINGS.4 Observation stations and hydro-logie conditions " 1.5 Oceanographic conditions 14 1,6 Historical disasters of typhoons and storm surges. 18 CHAPTER 2: MODELLING OF NON-TYPHOON CONDITION.1 Introduction model MIKE 21 20 2.2 Module MIKE 21 Flow Model (MIKE 21 FM).2, Model setup and boundary conditions.1 Analysis data and choose scope of model, 25 2.2 Building mesh model two-way 26 2.1 Analysis and choice of time and calibration data model.2 The parameters and model calibration process 34 2.3 Results of model calibration 34 2.1 The parameter for verification 2.2 The result of verification model.4 Conclusions CHAPTER 3: MODELING OF STORM SURGE 3.2 Modeling of typhoon 3.1 Theoretical basis of establishing patterns of wind and barometric pressure in the storm 40 3.2 Wind field model in the storm 40 3.3, Modelling of pressure in storm.Model setup and boundary conditions.2 Set of hydraulic parameters.1 Analyze and choose the time and calibration data model.2 Parameters and model calibration process s 3.5 Model verification sf 3.1 Set up model verification sf 3.2 The result of verification 56 3.6 Conclusions 56 (CHAPTER 4: SENSITIVITY ANALYSIS MODI ST 4.1, Role ofpressure center in the storm sĩ 4.1 Set of hydraulic parameters, sĩ 4.
Role of parameters model (B) 62 42.1 Set of hydraulic parameters. Results model 63 423, Results analysis 64 4.3 Role of maximum wind speed in the storm.1 Set of hydraulic parameters.4 Role ofradius maximum in the storm 66 4.1 Set of hydraulic parameters 66 4.5 Role of wind friction (Ca) 68 4.6 Role of trajectory of storm, 7 4. Set of hydraulic parameters.2 Results model: Tà 4. 75 CHAPTER 5: CONCLUSIONS AND RECOMMENDATIONS.2 Recommendations, 78 REFERENCES 79 APPENDIX! LIST OF FIGUES Figure I: Administrative Map of South Central Coast Figure1.
2 Observation stations in south central coast Figure 1. 3: Cau Da station ~ Khanh Hoa province Figure 1. 4: The monitoring sites of Vung Tau station Figure 1, 5: The significant wave height patterns in the East Sea Figure 2 1: Introduction MIKE 21 Figure 2 2: Scope of model Figure 23: Topography of study area Figure 24 Simulated area Figure 25 Building topography data, Figure 26 Model boundary conditions 31 Figure 27 Diagram of calibration process 3 Figure 2 8 Calibration station 33 Figure 2 9 Comparison of water level at Cau Da observation station 3s Figure 2 10 Comparison of water level at Vung Tau observation station 35 Figure 2 11 Comparison diagram in Cau Da station. 37 Figure 2 12 Comparison diagram in Vung Tau station 37 Figure 31 Storm surge Figure 32: Typhoon #21 in 2007 Figure 3 3: Typhoon #23 in 2009 Figure 34: Wind field model Figure 3 5: Data provided for the wine field model Figure 3 6: Wind speed in the typhoon in 2007.
Figure 3 7: Wind pressure in the typhoon in 2007 51 Figure 3 8: Comparison diagram in Cau Da station 11/2007 = Figure 3 10: The parameter of storm #23 in 2008 s Figure 311: Wind speed inthe typhoon in 2009 s Figure 3 12: Wind pressure in the typhoon in 2009 s Figure 3 13: Comparison diagram in Cau Da station in 2009 56 Figure 41 The relationship between Vinax and AP. s Figure 4 2 The positions extract 60 Figure 4 3 Storm surge in Quy Nhon ~ Bình Dinh ot Figure 4 4 Storm surge in Nha Trang ~ Khanh Hoa ot Figure 4 5 Storm surge in Vung Ro~ Phu Yen “ Figure 46 Storm surge in Quy Nhon ~ Bình Dinh 6 Figure 4 7 Storm surge in Nha Trang — Khanh Hoa 63 Figure 4 8 Storm surge in Vung Ro ~ Phu Yen, 6 Figure 4 9 Storm surge in Quy Nhơn ~ Bình Dinh 65 Figure 4 10 Storm surge in Nha Trang ~ Khanh Hoa 6 Figure 411 Storm surg in Vung Ro~ Phu Yen. 6 Figure 4 12 Storm surge in Quy Nhon ~ Bình Dinh o Figure 4 13 Storm surge in Nha Trang ~ Khanh Hoa o Figure4 14 Storm surge in Vung Ro~ Phu Yen 6 Figure 4 15 Storm surge in Quy Nhon ~ Binh Dinh © Figure 4 16 Storm surge in Nha Trang ~ Khanh Hoa 70 Figure 4 17 Storm surge in Vung Ro~ Phu Yen 20 Figure 4 18 Typhoon #23 in 2009 m Figure4 19 The storm hits Binh Dinh province 2 Figure 4 20 The storm hits Nha Trang province 72 Figure 421 The storm hits Ninh Thuan province Figure 4 22 Storm surge in Quy Nhon ~ Binh Din 73 Figure 423 Storm surge in Vinh Xuan Dai ~ Binh Dia 73 Figure 424 Storm surge in Vung Ro~ Phu Yen 7 Figure 425 Storm surge in Nha Trang ~ Khanh Hoa 74 Figure 4 26 Storm surge in Cam Ranh ~ Khanh Hoa 74 Figure 4 27 Storm surge in Mui Padaran ~ Ninh Thuan, 74 LIST OF TABLES ‘Table 1 1 Statistics storm in Vietnam. Table I 2 Statistics storm in South Central Coast province from 1951 to 2010.
Table 2 1 Model boundary conditions 30 ‘Table 2 2 the parameters effect to Nam Trung Bo model 31 Table 2 3 Relevance of NASH coefficient 34 ‘Table 2 4 Results of model calibration 35 Table 2 5 Results parameter of model after calibration 36 ‘able 3 1 Wind speed according tothe Beaufort wind sele 44 Table 3 2 Parameters of wind fied 48 ‘able 3 3: The data of Typhoon #21 in 2007 (grade 11) 49 ‘Table 3 4: Set of hydraulic parameters. 32 ‘Table 3 5: The result of model calibr ion 53 Table 3 7: The result in observation station in Storm 56 ‘Table 4 1 The input parameters of the models 60 Table 4 2 The coordinate of positions extract INTRODUCTION 1. Problem identification and the necessit of the study ‘The South Central Coast of Viet Nam is characterized by a long coastline with many rivers, estuaries , which is good condition for farming, fishing. Its geography, terrain and natural conditions have strong influence on its geology, climate, hydrology, other natural resources.
This area often suffers a lot of natural disasters such as storms, floods and drought. ‘The South Central Coast is an important region in defense and economic strategy. Many seaports, transportation systems and railways and roads have been built in the coastal zone to facilitate economic and cultural exchanges between South — North; and international exchange. However, this region is one of the most vulnerable places to natural disasters, especially floods (e.
Large floods occurred in Central and South Central in: 1952, 1964, 1980, 1990, 1996, 1998, 2003, 2008). In fact, there are at least 8 types of natural disasters and hazards which occur in this region such as: storms, floods (including flash floods), droughts, landslides, cyclones, salinity intrusion and erosion of the riverbanks, while there are five phenomena related to typhoons and storm surges, According to Hang et al. (2010), on average, Vietnam suffers from 5 to 7 typhoons per year along its coastal zone. From 1951 to 2006, the activities of typhoons in South East of Pacific Ocean tend to reduce in the number of weak and average typhoons, while the number of strong typhoons tends to increase.
In West Sea, the typhoons, which only act in sea, tend to increase, but typhoon’s intensity tends to reduce. In recent years, the number of typhoons directly impacting on Northern reduces and the Southern in Vietnam inereases. The number of typhoons reduces, but more super typhoons appear, which causes great damage to people and property, such as Hurricane Katrina hitting the United States in 2005, Cyclone Nargis hit Myanmar in 2008, ‘Typhoon Bopha in 2012. Almost population living in coastal area are often attached by typhoon.
When typhoons hit coastal area, water level increases, and destroying structures and houses nearby coastal zone. When typhoon combines with high tide, water level increase more and more, and consequently even more serious. Hundreds of people dead or ‘missing and thousands of people affected by the storm and flood each year. Damage to property such as lost homes, erops, damaged the social-economic works of up to tens of billions, The South Central Coast is often threatened by coastal erosion, broken di flooding or salinization caused by storms, especially in the coastal area which is densely populated and developed economic, Tourism is very vulnerable and at very high risk.
Therefore, the study of storm surges for South Central Coast is essential. We can forecast flood for vulnerable areas and the impact during storm landfall. Beside, we proposed mitigation measures natural disasters, risk of environment in the context of climate change increasingly unpredictable and the effect ofclimate change will make typhoons increased more in the future. Literature review Storm surge is an abnormal rise of water generated by a storm, over and above the predicted astronomical tides.
Storm surge should not be confused with storm tide, ‘hich is defined as the water level rise due to the combination of storm surge and the astronomical tide, This rise in water level can cause extreme flooding in coastal areas particularly when storm surge coincides with normal high tide, esulting in storm tides reaching up to 6m or more in some cases. Storm surge is produced by water being pushed toward the shore by the force of the ‘winds moving eyelonically around the storm. The impact on surge of the low pressure associated with intense storms is minimal in comparison to the water being forced toward the shore by the wind The maximum potential storm surge for a particular location depends on a number of different factors. Storm surge is a very complex phenomenon because it is sensitive to the slightest changes in storm intensity, forward speed, size (radius of maximum winds-RMW), angle of approach to the coast, central pressure (minimal contribution in comparison to the wind), and the shape and characteristics of coastal features such as bays and estuaries.
The effects of storm surge very serious. For example, when Hurricane Katrina approached the US coast in 2005, it generated a storm surge of more than 8 meters some areas, This led to widespread flooding, including almost all of the city of New Orleans where the sea defenses couldn't cope with the water level More than 1800 people were killed across the US by Hurricane Katrina, many ofthem by the storm surge flooding.