| The Nanjing City has a northern subtropical monsoonal climate, with abundant precipitation mainly occurring from June to September. Further, heavy rainstorm in flood season and strong weathering of rock make the increase of erosion potential. Serious soil and water losses may be occur due to rapid urbanizing and industrializing, it not only threaten environment and city scenery, but also affect sustainable developments of economy and society. In this study, geographical information system of soil and water conservation is established supported by Arc/Info,ArcView and VB software ,and programming of soil and water conservation in Nanjing City is carried out. The results provide favorable soil and water environment of city development and foundation of internationalization, and it give advices for the research and practice of GIS in city. The data of GIS of soil and water conservation in Nanjing is mainly composed of space and attribute databases. The space database includes parameter charts of soil and water losses, charts of soil and water losses. Also, charts of soil and water losses control in different region, traffic charts, water area charts, administration charts, and basic data charts are stored in the space database. The attribute database includes datasheets about various vectors. While documentation of rule and law, technical critetion and experiment data form relational database. The status of soil and water losses during 1997-2000 in Nanjing is analyzed using GIS of soil and water conservation and model of soil and water losses. The area of soil and water losses, annual amount of soil erosion, and mean annual soil erosion modulus belonging to low degree and more than low degree (>500t/km2·a) are 1288 km2, 335×104 t and 2603t/km2·a respectively. The detailed status of soil and water losses is obtained through the nesting of monitoring results in middle areas, which helps to integrated control of soil and water losses. In addition, 322 small watersheds in Nanjing City are divided according to borderline of countries, topographty and water system conditions, and amount and area of soil and water losses are fixed to individual small watershed based on GIS database. In this dissertation, application of this system in the programming and control of classical small watershed is discussed. According to monitoring results of this system, land function, characteristics of soil and water losses, and objective type of prevention and control in programming region, districts of stress control, stress monitoring and stress prevention and protection are divided. Further, the range, object, role and detailed control management in individual district are put forward.
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