Graduate School of Frontier Sciences, the University of Tokyo Graduate Program in Sustainability Science 2009-2010 Master’s Thesis Land Use/Cover and Surface Water Quality at Multiple Spatial Scales in the Kanto Region Submitted in February 2010 Supervisor: Professor Takashi Oguchi Advisor: Professor Makoto Yokohari (47-086823 Andy Darmawan) Abstract Previous research has shown that water quality in a river basin is affected by its land use/cover. However, more research is needed because findings so far vary from one river basin to another. This research assesses relationships between land use/cover and water quality in river basins of the Kanto region, Japan. First, land use/cover changes during 1983–1986, 1989–1992, and 1995–1999 were analyzed. It was found that the changes were decreased in number with time, but increased in average size. Their spatial distribution also extended from urban and agricultural areas to forest in the upper reaches. A larger percentage of forest was converted into land constructed for residence/factories and cultivated meadows. Agricultural areas including paddy fields were also converted, especially into land constructed for residence/factories. Second, temporal trends of water quality were analyzed. The results show overall improvement of water quality in most river basins since the 1970s, which can be attributed to the enforcement of the Environmental Pollution Prevention Law. However, degradation of water quality due to nutrient concentration was observed in some river basins. Spatially, lower water quality occurs in areas dominated by urban and agricultural land use/covers. Therefore, pollution controls applied to these areas will improve water quality. Correlation and multiple regression analyses indicate that, for the spatial scale of the whole Kanto region, water quality is mainly related to percentages of factory/industrial areas, those of urban districts with a few trees, and those of urban/residential districts with many trees. This indicates that despite the presences of sewage systems and wastewater treatment plants, anthropogenic activities associated with land use/cover remain affecting water quality. Weed communities including those on the roadside and in both cultivated and uncultivated paddy fields play a significant role in determining water quality in the spatial scale of river basins. This suggests that resuming agriculture in areas with unmanaged weed communities will improve water quality. i Altering spatial scales used in the correlation analysis of land use/cover and water quality including multiple regression led to different results. This indicates the importance of spatial scales in analyzing relationships between land use/cover and water quality. Therefore, plannings of sustainable development should consider the use of multiple spatial scale approaches to protect water quality in an appropriate manner. Keywords: Land use/cover, Water quality, Kanto region, River basin ii Declaration This thesis is a presentation of my original research work. Wherever contributions of others are involved, every effort is made to indicate them clearly, with due reference to the literature, and acknowledgement of collaborative research and discussion. ____________________________ Date: ……………………………... iii Acknowledgments First, I offer my sincerest gratitude to my supervisor, Professor Takashi Oguchi, who has supported me throughout my thesis with his patience and knowledge whilst allowing me the room to work independently. I attributed my Master’s degree to his encouragement and effort and without him, this thesis would not have been completed or written. One simply could not wish for a better or friendlier advisor. I would also like to express my deepest gratitude to my advisor Professor Makoto Yokohari for his patient guidance, critical comments, and excellent suggestions throughout this research project. I appreciate his vast knowledge and skills in many areas. I would also like to thank the other professors in the Graduate Program of Sustainability Science for sharing their knowledge throughout my study and for building a better understanding in sustainability science. I would like to thank Jiro Kogi for sharing me his knowledge on water quality and for helping me obtain GIS data for the Kanto region. I am indebted to Erwin Hardika Putra for his advices on water quality and river basins, and Leony Olivia Unsulagi for her assistance in reviewing my thesis draft. I recognize that this study would not have been possible without the financial assistance from The University of Tokyo’s President Scholarship. I am also indebted to my colleagues in the Graduate Program of Sustainability Science for their help, valuable advices and being great friends during my study. Finally, I take this opportunity to express my profound gratitude to my beloved family for their moral support and patience during my study. iv Table of Contents Abstract ............................................................................................................................................ i Declaration ..................................................................................................................................... iii Acknowledgments.......................................................................................................................... iv Table of Contents ............................................................................................................................ v List of Figures ............................................................................................................................... vii List of Tables ................................................................................................................................. ix Chapter 1 Introduction ................................................................................................................... 1 1.1. Background .......................................................................................................................... 1 1.2. Literature review .................................................................................................................. 2 1.2.1. Land use/cover and its change in Japan ........................................................................ 2 1.2.2. Water quality and land use/cover .................................................................................. 4 1.3. Research objectives .............................................................................................................. 8 Chapter 2 Study Area ................................................................................................................... 10 2.1 Ara and Edo Rivers ............................................................................................................. 13 2.2. Fuji River ........................................................................................................................... 15 2.3. Kuji River ........................................................................................................................... 16 2.4. Naka River ......................................................................................................................... 17 2.5. Sagami River ...................................................................................................................... 18 2.6. Tama River......................................................................................................................... 19 2.7. Tone River ......................................................................................................................... 20 Chapter 3 Data and Methods ........................................................................................................ 22 3.1. Data .................................................................................................................................... 22 3.1.1. Hydrological data ........................................................................................................ 22 3.1.2. Land use/cover ............................................................................................................ 23 3.1.3. City planning data ....................................................................................................... 23 3.1.4. Digital elevation model ............................................................................................... 23 v 3.2. Methodology ...................................................................................................................... 24 3.2.1. Data collection and arrangement ................................................................................ 24 3.2.2. Terrain data processing ............................................................................................... 27 3.2.3. Data analyses .............................................................................................................. 28 Chapter 4 Results ......................................................................................................................... 29 4.1. Land use/cover changes ..................................................................................................... 29 4.2. Water quality changes ........................................................................................................ 64 4.3. Spatial distribution of water quality ..................................................................................