Gemma Louise Ives the University of Sheffield Department of Geography
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Gemma Louise Ives The University of Sheffield Department of Geography A history of the monsoon in southern India between 1730 and 1920 and its impact on society: with a particular focus on Tamil Nadu. PhD Thesis A thesis submitted in partial fulfilment of the requirement for the degree of Doctor of Philosophy March 2020 Abstract The field of historical climatology has rapidly developed over the past two decades, driven by the understanding that improving the knowledge of the past can help make informed decisions about the future. Most studies currently focus on mid-latitude regions, whereas, this thesis is part of a growing body of work that seeks to expand the methodology into tropical and subtropical regions. Because of India’s colonial past, there is a substantial amount of extant, English language documentation available to researchers and these documents can help to build an understanding of both historical monsoon magnitude and changes in the social-ecological systems of the past. This thesis firstly explores the application of two types of documentary evidence for reconstructing the monsoon of Southern India, with a focus on the northeast monsoon of Tamil Nadu between 1730 and 1920. The first type is terrestrial documentation; this predominantly consists of government records, diaries, correspondence, historical accounts, newspapers and early instrumental records. The content of these documents was calibrated to modern instrumental rainfall, creating a five-point index of northeast monsoon magnitude, the first reconstruction of its length and resolution for the region, which had a strong correlation with modern instrumental data of 0.74, significant at the 0.05 threshold. The reconstruction was extended to present using degraded modern instrumental data: this new dataset showed that there is persistence in the cyclic pattern of increased and decreased monsoon rainfall, with approximately six epochs, each containing a period of above and below normal northeast monsoon rainfall between 1730 and 2017. The quality of this reconstruction was sufficient to investigate teleconnections between the northeast monsoon and the Indian Ocean Dipole and El Niño Southern Oscillation over nearly three centuries. This study demonstrated a non-stationary relationship between northeast monsoon rainfall and each of the two climate drivers, with good agreement between strong El Niño/La Niña and strong positive IOD events and normal-increased or normal-decreased northeast monsoon magnitude. Secondly, this thesis explored the use of data from within ships’ logbooks to reconstruct monsoon magnitude between 1750 and 1920, for both Kerala and Tamil Nadu and for each rainfall season. Two reconstruction methods were explored, composite plus scaling, and principal component regression. Interestingly, due to the unique monsoon climate and the need to adequately resolve it in both time and space, these reconstructions were less successful than their terrestrial counterpart. This thesis goes on to use the information contained within the documentary sources to explore details of historical famine events in the region of modern day Tamil Nadu. These periods of famine were identified and characterised. The management strategies employed by government and their changes over time were identified, revealing a distinct and widespread transition to non- interventionist famine management on the part of the British government at the turn of the nineteenth century. Finally, this thesis uses the new northeast monsoon reconstruction to explore the interwoven relationship between political failure, rainfall and famine. Acknowledgements Firstly, I’d like to thank my supervisors, Dr. Julie Jones, Prof. Grant Bigg, Dr. George Adamson and Prof. David Nash for all the support, feedback and guidance they have given me throughout the process. Also, thanks to the University of Sheffield for funding the project and all the staff in the Geography building. This thesis wouldn’t have been possible without the love and support that I’ve received from my family and friends. Thanks to Joe and Fudge for making home the happiest place in the world. To my parents, Diane and Rob, for supporting me every step of the way and for being unfailingly proud of me, no matter how small my achievement. To my brother, Tiff, Poppy and Eden for believing in me and for always being there when I needed them. To Janet and Steve, for all the support and the snacks. Of course, my thanks to the cutlery draw, James, Rachel, Niall, Shauna, Hannah and James, who were all in this with me from start to finish and who never, even for one second, let me doubt myself. Finally, thanks to everyone on A-floor for the tea breaks, the advice and for making each day as bright as can be! Thanks everyone. Contents 1 Chapter 1: Research context and aims 1.1 Structure of the thesis 2 Chapter 2: Scientific background and historical context 2.1 Study area Kerala Tamil Nadu 2.2 India’s mean monsoon Winter Pre-monsoon The southwest monsoon The northeast monsoon 2.3 Changes in the monsoon El Niño-Southern Oscillation (ENSO) The Indian Ocean Dipole Trends in monsoon rainfall 2.4 Political history of India 1730-1947 Trading and war making. Early exploits of the East India Company East India Company as Landholders in Madras The fall of the East India Company 2.5 Chapter Summary 3 Chapter 3: Terrestrial documentary monsoon reconstruction 3.1 Introduction 3.1.1 Historical climatology 3.2 Data collection 3.1.2 Indian Institute of Tropical Meteorology rainfall data 3.1.3 Archival exploration and documentary data 3.3 Methods 3.1.4 Indices of monsoon magnitude; documentary data 3.1.5 Indices of monsoon magnitude; early instrumental data 3.3.3. Combining the early instrumental and the documentary series 3.3.4. Confidence values 3.4. Results 3.4.1. Extension of the documentary series to present 3.5. Comparison with existing rainfall reconstructions 3.5.1. Comparison with existing documentary studies 3.5.2. Comparison with dendroclimatic reconstructions 3.5.3. Comparison with ENSO and IOD 3.6. Conclusions 4 Chapter 4: Reconstructing monsoon magnitude using data from ships’ logbooks 4.1 Introduction 4.1.1 Ships’ logbooks 4.2 Pre-processing of logbook data 4.3 Determining the spatial domain of the reconstruction Reanalysis data The Relationship between Wind and Rainfall over Tamil Nadu The Relationship between Wind and Rainfall over Kerala 4.4 Reconstructing monsoon magnitude 4.1.2 Model fitting and validation using CPS 4.1.3 Model fitting and validation using PCR 4.5 Threshold selection 4.6 Confidence Values 4.7 Results of the logbook reconstructions 4.1.4 Keralan rainfall reconstructions 4.1.5 Rainfall reconstructions for Tamil Nadu 4.1.6 Comparison with the documentary reconstruction 4.8 Discussion 4.1.7 Threshold testing 4.1.8 Comparison between PCR and CPS methods 4.1.9 Comparison with the Documentary Reconstruction 4.9 Summary 5 Chapter 5: A famine history of Tamil Nadu 1730-1920 5.1 Introduction Climate and society in historical climatology Climate and society in the archives 5.2 Dearth and famine Pre-colonial period: 1730-1767 East India Company expansion: 1767-1807 East India Company Rule: 1807-1858 Crown rule: 1858-1920 5.3 Evolution of the key government response methods to famine Trade and distribution of food grains Relief works and charitable efforts 5.4 Famine and drought 5.5 Summary 6 Chapter 6: Discussion 6.1 Reconstructing the monsoon Terrestrial documentary reconstruction methods Logbook reconstruction methods Comparing the terrestrial and marine documentary reconstructions Extending the understanding of northeast monsoon magnitude 6.2 The monsoon and society A famine history Monsoon failure and famine 6.3 Chapter summary 7 Chapter 7: Conclusions and further work Conclusions Further work 8 References 9 Supplementary Information List of Figures Figure 2.1 - Modern states of India, with Tamil Nadu shown in red and Kerala shown in green .. 4 Figure 2.2 –Average monthly rainfall over Kerala and Tamil Nadu. Calculated for the period 1871-2014 using data from the Indian Institute of Tropical Meteorology (Mooley et al. 2016). Note the different scales on the top and bottom plots. .................................................................... 6 Figure 2.3 – Typical progression of monsoon onset and withdrawal. Monsoon onset is shown in blue, with accompanying dates on the left. Monsoon withdrawal is shown in red, with accompanying dates on the right. (Adapted from: Indian Meteorological Department, 2015) ...... 8 Figure 2.4 - Mean 10m wind flow and surface pressure (hPa) during January. Data from ERA- Interim reanalysis, 1979-2017......................................................................................................... 9 Figure 2.5 - Mean 10m wind flow and surface pressure (hPa) during May. Data from ERA- Interim reanalysis, 1979-2017....................................................................................................... 10 Figure 2.6 - Mean 10m wind flow and surface pressure (hPa) during July. Data from ERA- Interim reanalysis, 1979-2017....................................................................................................... 12 Figure 2.7 - Mean 10m wind flow and surface pressure (hPa) during November. Data from ERA- Interim reanalysis, 1979-2017....................................................................................................... 13 Figure 2.8 – A schematic showing a simplified positive phase of the IOD. Adapted from Commonwealth of Australia (2013).