| The serious water losses and soil erosion in Loess Plateau not only confines the development of the local economy, but also the produced sediment continuously flows into Yellow River, raising the bed of Yellow River, increasing the danger of middle and lower reaches of Yellow River. Soil and water conservation of the Loess Plateau is arduous and the road will be long and tortuous. 89% of Loess Plateau sediment flows into Yellow River derived from gullies, so gully control is the key point. And silt storage dams, as one of the most important measure for gully control project in the Loess Plateau, play an important role in soil and water conservation. Planning and building silt storage dams scientifically and rationally not only can harness the Yellow River, realizing the country's Landscape Beautification Project, but also can improve and enhance the life quality of local people. Therefore, it has great practical significance.Loess Plateau in our country has unique geographic feature. International relevant researches and measures are very different from our country. However, we can draw lessons from out former work to develop Chinese dam system construction and planning, based on the current condition of our country and the actual situation of the small Watershed in Loess Plateau.Under guidance of relatively stabilization theory of dams system and the theory of channel grade and according to the national standards and specifications, reliable first-hand information is collected as the basis of data analysis. Then by employing powerful analysis function of GIS software and powerful data management capacity of geographic database, systematic small watershed dam system planning information system is developed to improve the work of the soil and water loss comprehensive harness of Loess Plateau. This paper is composed of 6 parts:1. Both domestic and overseas document related to silt storage dams are studied and current mainstream techniques are examined. The paper then summarizes the problems in silt storage dams projects construction in our country and in the world.2. Factors and their influence are analyzed which impact silt storage dams planning and construction. The article mainly discusses planning site, dam density, dam type, etc. then conclusions are drawn that major factors are cross section,gradient ratio,upper reaches water catchment area of every point of the channel, channel shape, channel level, rainfall, vegetation, the enthusiasm of local residents, and the original extent of soil erosion control.3. The hydrological model are developed using GIS technology to extracte the basic hydrological characteristic of the small watershed, provides data foundation for analyzing the influential factors. GIS models are adopted, of which some models are calibrated and improved. The influential factors are extracted as the basis for planning. And distribution maps of the influential factors are analyzed and derived. Finally geospatial database is built to store all the results and data.4. Technical process based on information system to plan silt storage dams is discussed and applied innovatively. In the planning, with a systematic consideration of influential factors, integrating influential factors (both their values and the extent they influence) and employing overlay analysis, the precise type and location of the planning dams can be calculated first from the large scale then the small-scale. In this way it can avoid re-planning caused by immature consideration.5. Small watershed dams planning information system is designed. The system architecture, function and type of integration are proposed and realized using VBA together with ArcObject to embed modules into ArcMap, where geodatabase is also integrated for efficient management.6. An application example of the small watershed dams planning information system is given in the paper. Shijiagou small watershed is taken as case study for the empirical research. Comparison is made between current planning scheme produced by program in this paper and the former planning scheme using traditional method. It result shows that although there's similarity in dams'style and location, yet the information system is capable of serving more data, making management more convenient, and realizing higher degree of visualization. Apparently, design with information system can meet multiple requirements of Shijiagou small watershed at different periods, and provide scientific and reliable technology platform for soil and water conservation work of the small watershed.Through the practical application on the study area it shows that planning with information system is more scientific and more reasonable. Research generality can provide technical support for the gully control of the soil and water conservation in whole region of Loess Plateau.
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