DEVELOPMENT OF STORM SURGE PREDICTION MODELS FOR THE BAY OF BENGAL AND THE ARABIAN SEA PADALA CHITTIBABU Centre for atmospheric sciences Submitted In fulfilment of the requirements of the degree of Doctor of Philosophy INDIAN INSTITUTE OF TECHNOLOGY, DELHI NOVEMBER, 1999 I Dedicated to My beloved mother CERTIFICATE This is to certify that the thesis entitled " DEVELOPMENT OF STORM SURGE PREDICTION MODELS FOR THE BAY OF BENGAL AND THE ARABIAN SEA " being submitted by PADALA CHITTIBABU for the award of the degree of DOCTOR OF PHILOSOPHY, is a record of the original bonafide research work carried out by him. He has worked under our joint guidance and supervision and has fulfilled the requirements for the submission of this thesis. The results presented in this thesis have not been submitted in part or full to any other University or Institute for award of any degree/diploma. C.-%4■Y1 (S.K.DUBE) (P.C.SINHA) Professor Professor Centre for Atmospheric Sciences Centre for Atmospheric Sciences Indian Institute of Technology Indian Institute of Technology New Delhi New Delhi ACKNOWLEGEMENTS I wish to express my deepest sense of gratitude and sincere indebtedness to my thesis advisors Prof. S.K. Dube and Prof. P.C.Sinha for suggesting research topic, their pains-taking guidance, constant encouragement , constructive criticism and ceaseless help through out this research work. I am grateful to Prof. U.C. Mohanty , Head, Centre for Atmospheric Sciences for making available necessary facilities in the department. I am also grateful to Dr A.D.Rao , P50 and Dr Y. R. Rao for their constant help, encouragement and valuable suggestions during entire my work. I would like to acknowledge the support of many faculty members of the centre. My sincere thanks are due to India Meteorological Department for providing necessary cyclone data and Department of Ocean Development for providing financial support. At this happy moment , I fondly remember my friends, seniors, colleagues and many others at the centre who made my stay a memorable one. My deep sense of gratitude to my wife Manjula and daughter Kritika who shown all the patience, co-operation and understanding during this period. Without their constant encouragement and co-operation this work would not have been possible. Above all , I express my heartfelt gratitude to my family members, especially my mother, brother, mother in law , co-brother, sister in law for their constant encouragement , emotional and whole hearted support. ...I-3 0\ ABSTRACT The development of real time operational surge prediction system in India is still limited and needs immediate attention. Keeping this in view a coastal zone storm surge prediction model has been developed for the east coast of India and also high resolution location specific surge and inundation models are developed for this region. A storm surge prediction model for the Southern Indian peninsula and Sri Lanka is also developed. Further, a fine resolution storm surge model is developed for the Gujarat coast. In chapter I, a brief review of the literature relevant to the studies made in the thesis has been given. Vulnerability of the Indian coast to storm surge hazard is discussed. Various methods of surge prediction is also described. A brief description of the existing models in India and nieghbourhood is also described in this chapter. Starting from the basic hydrodynamic equations governing the motion in the sea, chapter II describes the mathematical formulation of a depth-averaged coastal zone model. The model uses a curvilinear boundary and a non -uniform offshore grid spacing adjacent to the coastal boundary. Winds in the model are calculated by using a dynamic storm model. Using the data of 1977, 1982 and 1990 cyclones, the model is validated. Real time surge prediction has been done for 1993, 1995 and 1996 cyclone seasons. In chapter III, the development of a location specific high resolution model for Andhra coast is described. Using the model, storm surges are simulated for the severe cyclones that struck Andhra coast during 1891-1996 and the computed results are validated with the available observations. Frequency of occurrence relationships are obtained for various zones along the Andhra coast for risk analysis. This chapter also describes a high resolution model for the Orissa coast which is validated using the past cyclones that struck Orissa in recent times. In order to estimate the coastal flooding due to storm surges along the Andhra and Orissa coasts inundation models are developed in chapter IV by suitably modifying the location specific models described in the previous chapter. A continuously moving lateral boundary is modeled by using a finite difference technique. The model is validated by using the data of cyclones that struck Andhra coast during 1977 and 1990. A comparison also made between simulation using models with and without inland intrusion of water. Chapter V describes a numerical storm surge model has been developed for the southern Indian peninsula and Sri Lanka. Numerical experiments are performed with the help of the model to simulate the surge and sea surface currents generated by the 1964 Rameswaram cyclone, 1978 Batticaloa and 1992 Tuticorin cyclones. The results are in good agreement with the reported post storm survey information. Chapter VI gives a description of a fine resolution numerical model which has been developed for the prediction of storm surges along the Gujarat coast. Experiments are performed using wind stress forcing data representative of the 1982 Veraval cyclone, 1996 Diu cyclone and 1998 Kandla cyclone. The surge ii values computed by the fine resolution model is compared with those of the coarse resolution for the Gujarat coast. The last chapter gives brief conclusions drawn from the studies described in earlier chapters and an outline of the future course of studies has also been indicated. Ifi CONTENTS ABSTRACT LIST OF FIGURES AND TABLES CHAPTER I INTRODUCTION 1.1 Introduction 1 1.2 Tropical cyclone 4 1.2.1 Structure of the cyclone 6 1.2.2 Regions of formation 1.2.3 Frequency of occurrence of cyclones 8 1.2.4 Direction and movement of cyclones 9 1.3 Storm surges and their effect on coastal zone 9 1.3.1 Storm surges in the Bay of Bengal and the Arabian sea 11 1.3.2 Vulnerable areas of storm surges along Indian coasts 13 1.4 Data input for surge prediction 16 1.4.1 Oceanographic and hydrographic data 17 1.4.2 Meteorological input 18 1.4.3 Hydrological input 20 1.4.4 Basin characteristics and coastal geometry 21 1.4.5 Surface and bottom stress 21 1.5 Methods of storm surge prediction 22 1.5.1 Empirical methods 22 1.5.2 Graphical methods 23 1.5.3 Statistical methods 24 1.5.4 Analytical methods 25 1.5.5 Numerical storm surge prediction 25 1.6 Numerical modelling of storm surges in Indian seas 28 1.6.1 Model of Flier and Robinson (1972) 29 1.6.2 Model of Das et al. (1974) 29 1.6.3 The study of Ghosh (1977) 29 1.6.4 Model of Johns and Ali (1980) 30 1.6.5 Model of Das (1980 a) 30 1.6.6 Model of Das (1981) 30 1.6.7 Study of Johns (1981) 31 1.6.8 Model of Johns et al.(1981) 31 1.6.9 Other models 31 1.6.10 Real time prediction of storm surges 33 1.7 Objective of the thesis CHAPTER II Real time prediction of storm surges along the east coast of India 2.1 Introduction 46 2.2 Basic equations 48 2.3 Boundary and initial conditions 55 2.4 Determination of forcing functions 56 2.5 Formulation of the model 59 2.5.1 Introduction 59 2.5.2 Boundary conditions 60 2.5.3 Co-ordinate transformation 61 2.5.4 Fine grid resolution adjacent to the coast 62 2.5.5 Dynamic storm model 64 2.5.6 Numerical procedure 65 2.5.7 Stability of the scheme 71 2.5.8 Operating procedure of the model 71 2.6 Results and discussion 75 2.6.1 November 1977 Andhra cyclone 76 2.6.2 June 1982 Orissa cyclone 77 2.6.3 May 1990 Andhra cyclone 77 2.6.4 Real time prediction of storm surges of 1993 Karaikal, 1995 Gopalpur and 1996 Kakinada cyclone 78 2.6.4.1 December 1993 Karaikal cyclone 79 2.6.4.2 Nobember 1995 Gopalpur cyclone 80 2.6.42 November 1996 Kakinda cyclone 82 2.7 Conclusions 83 CHAPTER-III Development of storm surge prediction models for Andhra and Orissa coasts of India Part I : Storm surge prediction and frequency analysis for Andhra coast of India 3.1 Introduction 114 3.2 Frequency of severe cyclonic storms 116 3.3 The storm surge model 117 3.4 Model validation 119 3.4.1 May 1990 cyclone 119 3.4.2 November 1996 cyclone 120 3.4.3 Computed and Observed surges 121 3.5 Frequency analysis 125 3.6 Conclusions 128 Part II Numerical modelling of storm surges for Orissa coast of India 3.7 Introduction 130 3.8 Frequency of cyclonic storms 131 3.9 Model validation 133 3.9.1 1971 Paradip cyclone 133 3.9.2 1982 Paradip cyclone 134 3.10 Conclusions 135 CHAPTER IV Numerical modelling of inundation associated with storm surges for Andhra and Orissa coasts 4.1 Introduction 157 4.2 Formulation 158 4.3 Boundary conditions 159 4.4 Co-ordinate transformation 160 4.5 Inland intrusion 161 Part I : Inundation model for the Andhra coast 4.6 Introduction 163 4.7 Results and discussion 164 4.7.1 November 1977 cyclone 164 4.7.2 May 1990 cyclone 165 4.8 Conclusions 166 Part II : Inundation model for the Orissa coast 4.9 Introduction 167 4.10 Results and discussion 168 4.10.1 1971 Paradip cyclone 168 4.10.2 1982 Paradip cyclone 169 4.11 Conclusions 170 CHAPTER V Numerical simulation of storm surges along south Indian peninsula and Sri Lanka 5.1 Introduction 188 5.2 Formulation 188 5.3 Numerical experimentation 191 5.4 Results and discussion 193 5.4.1 1964 Rameswaram cyclone 193 5.4.2 1978 Batticoloa cyclone 196 5.4.3 1992 Tuticorin cyclone 198 5.5 Conclusions 199 CHAPTER VI Numerical simulation of storm surges along the Gujarat coast 6.1 Introduction 221 6.2 Formulation 222 6.2.1 Basic equations 222 6.2.2 Boundary conditions 223 6.2.3 Bathymetry in the model 223 6.3 Finite difference formulation 224 6.4 Numerical experimentation 227 6.5 Results and discussion 6.5.1 1982 Veraval cyclone 227 6.5.2 1996 Diu cyclone 229 6.5.3 1998 Kandla cyclone 230 6.6 Conclusions 233 CHAPTER VII CONCLUSIONS 7.1 Conclusions 242 7.2 Future work 245 .