STUDY OF GEOMORPHOLOGY AND DYNAMICS OF SHORELINE ASSOCIATED WITH MULKY-PAVANJE RIVERMOUTH, DAKSHINA KANNADA COAST, KARNATAKA, INDIA Thesis Submitted in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY By GUMAGERI NAGARAJ DEPARTMENT OF APPLIED MECHANICS AND HYDRAULIICS NATIONAL INSTITUTE OF TECHNOLOGY KARNATAKA, SURATHKAL, MANGALORE – 575 025 July, 2012 STUDY OF GEOMORPHOLOGY AND DYNAMICS OF SHORELINE ASSOCIATED WITH MULKY-PAVANJE RIVERMOUTH, DAKSHINA KANNADA COAST, KARNATAKA, INDIA Thesis Submitted in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY By GUMAGERI NAGARAJ (Reg.No. – 090707AM09F01) Research Supervisor: Dr. DWARAKISH G S DEPARTMENT OF APPLIED MECHANICS AND HYDRAULIICS NATIONAL INSTITUTE OF TECHNOLOGY KARNATAKA, SURATHKAL, MANGALORE – 575 025 July, 2012 i D E C L A R A T I O N by the Ph.D. Research Scholar I hereby declare that the Research Thesis entitled ―Study of Geomorphology and Dynamics of Shoreline Associated with Mulky-Pavanje Rivermouth, Dakshina Kannada Coast, Karnataka, India‖ Which is being submitted to the National Institute of Technology Karnataka, Surathkal in partial fulfillment of the requirements for the award of the Degree of Doctor of Philosophy in Civil Engineering is a bonafide report of the research work carried out by me. The material contained in this Research Thesis has not been submitted to any University or Institution for the award of any degree. GUMAGERI NAGARAJ (Register Number: 090707AM09F01) Department of Applied Mechanics and Hydraulics Place: NITK-Surathkal Date: 23 - 07 - 2012 ii C E R T I F I C A T E This is to certify that the Research Thesis entitled ―Study of Geomorphology and Dynamics of Shoreline Associated With Mulky-Pavanje Rivermouth, Dakshina Kannada Coast, Karnataka, India‖ submitted by Gumageri Nagaraj (Register Number: 090707AM09F01) as the record of the research work carried out by him, is accepted as the Research Thesis submission in partial fulfillment of the requirements for the award of degree of Doctor of Philosophy. Dr. Dwarakish G S Research Guide Date: 23 – 07 - 2012 Prof. Nagaraj M K Chairman – DRPC Date: 23 – 07 - 2012 iii DEDICATED TO MY PARENTS AND BELOVED TEACHERS... iv ACKNOWLEDGEMENT I would like to express my heartfelt thanks and gratitude to my supervisor, Prof. Dwarakish G S for his insightful guidance, continued inspiration and support, and great patience throughout the duration of this research, which made this study possible. It is a valuable experience to learn many aspects from him both as a teacher and a perfect human being. I admire among his other qualities, his kindness and balanced approach towards success and failure; his scientific foresight and excellent knowledge have been crucial to the accomplishment of this work. I consider myself privileged for having had the opportunity to conduct research in the area of coastal engineering under his able supervision. I am greatly indebted to Research Progress Appraisal Committee members, Prof. Subba Rao, Department of Applied Mechanics and Hydraulics and Assoc/Prof. U. Sripati, Department of Electronics and Communication Engineering, for their critical evaluation and very useful suggestions during the progress of the work. I would like to sincerely thank Prof. Nagaraj M K, Head, Department of Applied Mechanics and Hydraulics and Chairman RPAC for his continuous support, encouragement and timely help during my entire research period. I acknowledge my thanks to Prof. Lakshman Nandagiri, A/Prof. B M Dodamani Assoc/Prof. Paresh Chandra Deka, Department of Applied Mechanics and Hydraulics for their continuous encouragement, support and care during the course of my work. I also thank Assoc /Prof. Kiran G S, A/Prof. K Subrahmanya., Department of Applied Mechanics and Hydraulics, and Prof. D Venkat Reddy, Department of Civil Engineering NITK, Surathkal for their good wishes and moral support. I sincerely acknowledge to Mr. Srinivasulu Dandagala, Research Scholar, Department of Applied Mechanics and Hydraulics for his unique friendship and support while carrying out on site measurements and laboratory analysis during the research work. I sincerely acknowledge to Sri. B Jagadish, Foreman, Department of Applied Mechanics and Hydraulics, and Sri. Ananda Devadiga, Sri. Padmanabha Achary, Sri. v Gopalakrishna, Sri. Balakrishna, Sri. Deepak Sanil, Sri. Harish Salians, Sri. Harish D, and Mrs. Prathima Prakash for their support and help during the research work. I gratefully acknowledge the support and help rendered by the Post Graduate students, Mr. Mohan Kumar K N and Mr. Amruth Karjagi. I gratefully acknowledge the support of fellow Research Scholars during the research work. Without the support, patience and encouragement from my lovely family I could never have been able to submit this thesis. My most special gratitude goes to my Father, Basappa Gumageri and Mother, Laxmidevi B Gumageri for their continuous encouragement, patience and love. I express my special thanks to younger brothers Anand Kumar. B. G and Shreeshail Kumar. B. G and lovely younger sister Smt. Annapurna. H. N for their indirect support during this work. Finally, I would like to thank the Almighty God for blessing me with good health, ability to do work hard and guiding me in every success of my life. GUMAGERI NAGARAJ Place: NITK Date: 23 - 07 - 2012 vi ABSTRACT The current thesis considered Mulky-Pavanje rivermouth and associated shoreline of about 12km length, lies between 13000'00''-13006'00'' North Latitude and 74044'00''- 74050'00'' East Longitude of Dakshina Kannda coast, Karnataka, India for short-term (<10 years), medium-term (10–60 years) and long-term (>60 years) shoreline changes. Beach survey, beach width, wave climate (height, period and direction) and wind parameters (speed and direction) and sediment sampling are gathered from nine locations (BS 1 – BS 9) to represent total 12 km shoreline, during the period from September 2009 to December 2011 for short-term change analysis. Short-term change analysis indicated that net accretion on the beaches towards the south of the rivermouth (BS 1–BS 5), whereas the north of the rivermouth experienced net erosion (BS 6–BS 9). For medium-term shoreline change analysis, rainfall and river discharges are obtained from Indian Meteorological Department for the periods 1985- 2011 and 1985-1998 respectively. The monsoonal storm directly induces rivermouth morphology to vary (BS 5–BS 6), adjacent beaches to suffer from erosion (BS1–BS 4 and BS 7–BS 9) and also leads drastic changes in wave climate and freshwater flow. During monsoon and post-monsoon periods, the rivers Mulky (North) and Pavanje (South) overflow, discharge sizeable quantities of sediments into the sea, whereas during the pre-monsoon periods, seawater enters into the rivermouth area leads sediment deposition and distribution on either side of the rivermouth. However, the discharge of the Mulky river is approximately two times more than that of Pavanje river. Because of the more flow in the Mulky river, which runs across the northern part of the rivermouth, the shoreline in the vicinity of rivermouth is predominantly shifting towards south. Additionally long-term shoreline change analyses are made through multidated satellite imageries and topomaps for the period 1912–2009. The long-term shoreline change analyses depicts that northern spit and rivermouth are shifting towards south during the period 1912–2009 and also observed that fluctuation of accretion and erosion pattern on southern side of the shoreline is highly significant as compared with northern side. The Mulky-Pavanje rivermouth being highly complex and dynamic, but it provides wide scope for developmental activities around it. Therefore Land use/Land cover changes are attempted by considering recent viii decade, i.e 1998–2009 with the help of topographical map and remote sensing data. Land use/Land cover change analysis indicated that, because of development of urbanization and industrialization around the rivermouth, the built-up area has been drastically increased, while the other coastal related geological features such as beach vegetation, mangroves and river sand are drastically reduced during the period 1998– 2009. In addition, Artificial Neural Network (ANN) technique is used to model the very important parameters of the coastal engineering such as wave height and littoral drift, which cause coastal erosion in the study area. The developed NARX and FFBP models are evaluated using error statistics. In both cases the NARX model performed better than FFBP and proved that wave height and littoral drift are the direct responsible factors to cause erosion in the Mulky-Pavanje rivermouth and associated shoreline. Key words: Short-term, medium-term, Long-term, beach profile, sediment sampling, beach width, river discharge, rainfall, remote sensing, ANN, wave height, NARX, littoral drift, FFBP. ix TABLE OF CONTENTS Contents Page No Title Page i Declaration ii Certificate iii Dedication iv Acknowledgement v Abstract viii Table of Contents x List of Figures xv List of Tables xvii List of Abbreviation xx CHAPTER 1 INTRODUCTION 1.1 General 1 1.2 Coastal Processes and Shoreline Changes 2 1.3 Coastal Erosion in India 3 1.4 Coastal Erosion in Karnataka 6 1.5 Geomorphology of Dakshina Kannada 9 1.5.1 Physiography 9 1.5.2 Coastal Dynamics 9 1.5.3 Sea Bed and Coastal Sediments 10 1.5.4 Geology 10 1.6 Study Area 11 1.6.1 Reasons for the selecting the study Area 13 1.6.2 Oceanographic conditions 14 1.6.3 Metrological