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Mafikeng Campus Analysing Multitemporal Vegetation

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Mafikeng Campus Analysing Multitemporal Vegetation NORTii·WfST tJNIIJERS~':TY '!'UNIIJ.t:S!TI Y~ WKONE·BOPHiRIN.A t10flfl01YfS WHVFR~ITfiT MAFIKENG CAMPUS ANALYSING MULTITEMPORAL VEGETATION DENSITY IN THE UPPER MOLOPO RIVER CATCHMENT USING REMOTE SENSING TECHNIQUES Agnes Kyomukama Turyahikayo Thesis submitted in fulfilment of the requirements for the degree of Master of Science in Environmental Science May 2014 Supervisor: Prof. L.G. Palamuleni DECLARATION I, Agnes Kyomulcama Tmyahikayo, hereby declare that the dissertation for the Master of Science in Environmental Sciences at the North West University, hereby submitted has not previously been submitted by me in its entirety or in part for any degree at this or any other University, that it is my own work in design and execution and that all material contained herein has been duly acknowledged. SIGNED: ____A_r--_1 t_g-~--_· ______ Agnes Kyomukama Turyahilcayo DATE: DEDICATION I dedicate this dissertation to my late father, Peter Rwenzigye, my late mother,. Fidelis Kinlcuhaire Rwenzigye and my late husband, Dr. Bernard Turyahikayo. May their souls rest in eternal peace. ii ACKNOWLEDGEMENTS I would like to express my sincere appreciation to my Supervisor Prof. L.G. Palamuleni for her critical comments, encouragement and guidance throughout the thesis work. Her continual and excellent supervision has been of great value to me. The support she provided from the initial, to the final stage enabled me to develop an understanding of the subject. I highly appreciate her comments and cooperation tln·oughout the study. I would also like to acknowledge Prof. C. Munyati in a special way for introducing me to the science of remote sensing and his support and encouragement tln·oughout the study. I grate:fhlly acknowledge the generosity and cooperation of the North West University in financing part of my studies and resources towards making this thesis a success. I am also thankful to the late Mr L. Mald10ba and Mrs F. Malcgale whose support is highly appreciated for assistance with GIS map production. My sincere and heartfelt gratitude to my daughters (Claire, Cynthia and Charlotte) for their understanding and patience during the time of conducting the thesis, when they practically took over all household chores. Thank you so much for your support, prayers, and encouragement without which I would have given up. I would also like to express my appreciation to all my course mates for their friendship and for the wonderful events we shared together. Finally yet importantly, thanks to the Almighty God for making this study a success. iii ABSTRACT In arid and semi-arid environments like most of South Africa, the state of vegetation density in catchments is an important indicator of the state of the enviromnent, particularly because vegetation influences water availability by encouraging groundwater recharge. Because of the scarcity of water and consequent limits in abundance of vegetation in healthy green condition, in addition to climatic pressure, vegetation density in semi-arid enviromnents are under human use pressure. The upper Molopo river catchment area (UMRCA) in the North West Province of South Afi·ica is under this combined human use and rainfall pressure. This study aimed at assessing long-term changes in vegetation density in the upper Molopo river catchment area, resulting fi·om antlu-opogenic and rainfall pressures. Four Landsat images were utilized in analyzing the vegetation density change. For purposes of interpreting the changes identified, ancillary long-term data on anthropogenic factors (human population, number of houses, household use of wood as energy source, livestock populations) and rainfall were obtained from state sources. Vegetation density on the linages was enhanced using the Normalized Difference Vegetation Index (NDVI). The training data was then used for supervised maximum likelihood classification of the images into separate LULC as well as vegetation density (low, medium, high) maps for each elate. Assessment of accuracy indicated high classification accuracy of over 80%. The errors in classification were mainly clue to spectral signature confusion for the LULC classes. Change detection was then performed using the post-classification compmisons technique. Results indicated a growth in built up area from 3% in 1989 to 16% in 2013. The main indication of disturbance to .the vegetation was a sustained decline in medium vegetation density and its replacement by low vegetation density, particularly within 5km of human settlements. Hence, the study concluded that anthropogenic factors were the main cause of the decline in vegetation density in the UMRCA. Rainfall showed a cyclical pattern, with low seasonal rains (and high, negative Standardized Precipitation Index (SPI) values in the mid-1980s and positive SPI values thereafter, indicating that in the image period of analysis had wet conditions in general. Differences in rainfall prior to image date accounted for most of the inter-date variation in the vegetated LULC classes as well as water bodies. Long-term rainfall pattern did not have direct impact in the decline of medium vegetation density class in the UMRCA. However, there was a statistically significant negative correlation between human population and area of cover by iv medium vegetation density (r = -0.960, P < 0.01), implying that as human population increases, the medium vegetation density declines in area of cover. The decline in medium vegetation density in the Upper Molopo River Catchment is of ecological concern. There is a need for short tenn and long term strategies to ensure sustainable land management in the catclm1ent area, and in order to preserve vegetation density and biodiversity in their natural state. v TABLE OF CONTENTS DECLARATION ........................................................................................................... i DEDICATION ..............................................................................................................ii ACKNOWLEDGEMENTS .......................................................................................... iii ABSTRACT ............................................................................................................ iv TABLE OF CONTENTS .............................................................................................vi LIST OF FIGURES ..................................................................................................... ix LIST OF TABLES ....................................................................................................... X LIST OF ACRONYMS ................................................................................................xi CHAPTER 1 ............................................................................................................... 1 INTRODUCTION .................................................................................................... 1 1.1 Background ............................................................................................... 1 1.2 Statement of the problem .......................................................................... 2 1.3 Aim and objectives .................................................................................... 3. 1.4 Hypotheses ............................................................................................... 3 1.5 Rationale ................................................................................................... 4 1.6 Description of the study area ..................................................................... 4 1.6.1 Location setting ...................................................................................... 4 1.6.2 Climate ................................................................................................... 6 1.6.3 Vegetation .............................................................................................. 7 1.6.4 Soil types and distribution ....................................................................... 9 1.6.5 Land use pattern ..................................................................................... 9 1.7 Outline of the thesis ................................................................................. 10 CHAPTER TWO ....................................................................................................... 11 2 LITERATURE REVIEW ........................................................................... 11 2.1 INTRODUCTION ..................................................................................... 11 2.2 Key concepts about vegetation ............................................................... 11 2.3 Climate variability and vegetation density characteristics ........................ 12 2.4 Consequences of change in vegetation density on biodiversity . conservation ......................................................................................................... 16 2.5 Role of vegetation density in ephemeral rivers ........................................ 21 2.6 Remote sensing and vegetation characteristics ...................................... 25 2. 7 Summary ................................................................................................. 32 vi CHAPTER 3 ............................................................................................................. 34 3 RESEARCH METHODOLOGY ............................................................... 34 3.1 INTRODUCTION ....................................................................................
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