TRANSFORMATION OF VALLEY-BOTTOM CULTIVATION AND ITS EFFECTS ON TANZANIAN WETLANDS: A CASE STUDY OF NDEMBERA WETLAND AREA IN IRINGA REGION By LUCY MAGEMBE A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2007 © 2007 Lucy Magembe 2 To my son, George, and daughter, Iman, who fill my life with joy and whose presence encourages me to fight my battles earnestly so as to be able to provide for them. 3 ACKNOWLEDGMENTS Many people provided invaluable support. Since it is impossible to acknowledge each person individually, I extend my sincere appreciation to all who played a part in this work. However, I feel obligated to thank individually a few people who have given generously of their time, knowledge, expertise, and moral support. First and foremost, I extend my deep appreciation to my supervisory committee chair (Dr. Michael Binford) for his invaluable assistance, advice, and encouragement. He practically challenged me to work independently but continued to stimulate my analytical thinking, enabling me to improve my writing skills. I am indebted to my committee members Dr. Abe Goldman and Dr. Sandra Russo for helping me grow intellectually and develop a more focused thesis. Their input to this work and their attention are highly appreciated. I extend my sincere gratitude to my sponsors, The United States Agency for International Development (USAID) and the Africa-America Institute (AAI), who made my stay in the United States content and without whose financial support this work would not have come to fruition. In Tanzania, I would like to thank the people of Iringa and Mufindi Districts for their time, support, and kindness. Sincerest appreciation is extended to the District Facilitation Teams and to WWF (World Wide Fund for Nature) staff for their endless support during fieldwork. I thank members of staff and students of the Geography Department at the University of Florida for their moral support and for providing a social and academic atmosphere in which I was able to grow. My gratitude goes to my husband, George Magembe, my sister Annamarie Kiaga, and my late mom, Mrs. Tabitha Kashaija for their continued love, support, encouragement, and for believing in me. 4 No words can express how grateful I am to the Mkanta family for allowing me to stay with them for endless weeks while completing my thesis. A heartfelt gratitude goes especially to Dr. William Mkanta for his assistance in statistical methods. Anna Mushi, Tunu Mndeme, Simon Mwansasu and Juma Rajabu Mshana are acknowledged for their assistance in perfecting the aerial photo interpretation and GIS analysis. Lastly, I give thanks and praises to the Almighty God for the blessings in my life, but mostly for enabling me endure the stresses associated with graduate schooling. 5 TABLE OF CONTENTS page ACKNOWLEDGMENTS ...............................................................................................................4 LIST OF TABLES...........................................................................................................................9 LIST OF FIGURES .......................................................................................................................10 ABSTRACT...................................................................................................................................11 CHAPTER 1 INTRODUCTION ..................................................................................................................13 1.1 Background and Statement of the Problem ......................................................................14 1.2 Significance ......................................................................................................................16 1.3 Objectives .........................................................................................................................17 1.4 Study Questions................................................................................................................17 2 LITERATURE REVIEW .......................................................................................................21 2.1 Introduction.......................................................................................................................21 2.2 Conceptual Framework.....................................................................................................21 2.2.1 Concepts of Land-Use and Land-Cover Change....................................................21 2.2.2 Human-settlement Models of Land-Use ................................................................24 2.2.3 Population Growth and Agricultural Land-Use .....................................................26 2.2.4 Drivers of Smallholders Farming Decisions ..........................................................29 2.2.5 Decline in Agricultural Production and its Relation to Land Use..........................32 2.2.6 Wetlands: An Alternative Landscape Component for Crop Production ................34 2.2.7 Irrigation Practices and Wetland Use in Tanzania .................................................37 2.3 Summary of the Theoretical Background and Formulation of Hypotheses .....................40 2.3.1 Summary of the Theoretical Background...............................................................40 2.3.2 Justification of the Hypotheses...............................................................................43 3 STUDY OF FARMER AND HOUSEHOLD FACTORS INFLUENCING VINYUNGU FARMING SYSTEM .............................................................................................................45 3.1 Study Area ........................................................................................................................45 3.1.1 Location..................................................................................................................45 3.1.2 Physical Environment.............................................................................................45 3.1.3 Demographic Characteristics..................................................................................46 3.1.4 Socioeconomic Situation........................................................................................46 3.1.5 Agriculture..............................................................................................................47 6 3.2 Material and Methods.......................................................................................................48 3.2.1 Sample Profile and Sampling Procedure................................................................49 3.2.2 Data Collection.......................................................................................................50 3.2.3 Methods of Data Analysis ......................................................................................54 3.2.3.1 Descriptive Statistics....................................................................................55 3.2.3.2 Measures of Associations.............................................................................55 3.2.3.3 Multivariable Analysis .................................................................................55 3.3 Results: Farmer and Household Characteristics of Valley-Bottom Cultivation (vinyungu) around the Ndembera Swamp in Iringa and Mufindi Districts.........................56 3.3.1 Sociodemographic Characteristics .........................................................................56 3.3.1.1 Land tenure/ownership.................................................................................58 3.3.1.2 Crop production, crop preference and land use............................................59 3.3.1.3 Inputs on vinyungu .......................................................................................60 3.3.1.4 Multivariable analysis ..................................................................................61 3.3.2 Environmental Issues Related to Vinyungu Cultivation.........................................64 3.3.3 Discussion...............................................................................................................65 4 USE OF GEOGRAPHIC INFORMATION SYSTEMS AND REMOTE SENSING TO DETERMINE THE MAGNITUDE AND RATE OF CONVERSION OF NDEMBERA SWAMP AS A RESULT OF VINYUNGU EXPANSION.....................................................79 4.1 Data Sets ...........................................................................................................................80 4.2 Methods ............................................................................................................................80 4.3 Data Analysis....................................................................................................................81 4.4 Results...............................................................................................................................81 4.5 Discussion.........................................................................................................................82 5 DISCUSSION AND CONCLUSION ....................................................................................91 5.1 Introduction.......................................................................................................................91 5.2 Major Findings..................................................................................................................91