Research On Spatial Decision Support System For Slope Regulation Planning Of Small Watershed

Slope control of small watershed, as the first line of defense to prevent and control soil and water loss in loess plateau, is an important measure to improve the ecological environment in the region. The implementation of slope control will directly affect the construction of project on soil and water conservation and hydraulic conservancy of the whole watershed. A well-designed planning scheme of slope control makes great difference to successful comprehensive harness of the whole small watershed. Slope control, as a fashion of spatial planning, faces many problems related to spatial distribution. It is key to analyze and apply abundant spatial information in order to make reasonable planning.Firstly,based on related theory, the thesis analyzes the application of GIS on the control soil and water loss in small watershed and soil and water conservation project, then the aim and meaning were discussed as for developing spatial decision support system for slope regulation planning of small watershed.Secondly, combining with the characteristics of soil and water conservation for small watershed in loess plateau, this thesis analyzes: a. the basic content of slope regulation planning of small watershed; b. the procedure of dealing with the information in planning; and c. the objective of system design and its functional requirement. On this basis, geographic information system software development on using ArcObjectsTM (ArcObject is the Trademark of ESRI Inc.) component technology is analyzed briefly. Then software development is employed in the working environment of ESRI ArcGIS 9.0, with the fashion of AO+VBA (VBA is the integrated development environment of Visual Basic Macros in ESRI ArcMap 9.0). During the process of constructing spatial database, data requirement of slope regulation planning of small watershed is analyzed, and a strict sense of geographic database is realized by employing spatial data model technology.After having analyzed and processed the planning data, a series of work is done as follows:(1)RUSLE is used as the soil erosion model to estimate the annual average amount of soil erosion. The method on calculating variables (loss factors) of RUSEL is also studied. The model is capable of calculating the soil and water loss quantitatively, analyzing layers of soil and water loss factors, determining the current soil erosion for a given watershed region.(2)Under guidance of foundation theories, the system of land suitability evaluation indices is established. The weight of each evaluation factor is determined by AHP. Then accumulation decomposition model is used to calculate the total value of land suitability evaluation. After that he result is classified automatically to determine the suitability of land parcels for every land use pattern.(3)The method of Linear Planning is employed to optimize the land use structure. A linear planning model is developed for land use. Also the problem of how to select and determine parameters of the model is studied. Here simplex method is used in establishing the linear programming model.(4)On the basis of planning theory of soil and water conservation for watershed, together with the results from the models developed in the paper, planning rules are made accordingly to position all kinds of measures appropriately. Then the planning land use for the small watershed is charted. The planning result is examined with high scrutiny.Finally, the system is developed and it takes jingjiahe watershed as an example to simulate the total slope regulation planning. And the result is analyzed critically.Through the above research, some conclusions are drawn as following: based on related theories, together with author's former theory and experience acquired from soil and water conservation work in loess plateau, the spatial decision support system of small watershed for slope regulation planning can be developed successfully with high operability. The system realized the computerization of small watershed slope regulation planning. By using computer to process data and realize space location the regulation can be done more scientifically than in traditional manner. The application of the system can help solve the problem of all kinds of information analysis processing and control measures disposition, which can improve the efficiency and make planning work even more scientific and reasonable.