Decision-Making Support Of The Spatial Information Technology For The Pre-feasibility Research On Hydroelectric Project

Much practice shows that spatial information technology can afford an objective and scientific decision-making support for all kinds of projects, because of it's excellent function during information obtaining and spatial analysis."What the spatial information technology can do during the Pre-feasibility Research on Hydroelectric Project?", which is the theme of this paper. It focuses on technical methods of RS and GIS are applied into pre-feasibility research on hydroelectric project, taking the Maerdang Hydropower Station on the Yellow River as an example. Main research works of this paper are the following.(1) Multi-source spatial data arc successfully integrated, which provide data support for GIS decision analysis.In view of the issue of multi-source spatial data, three commonly used methods of data integration, which are data format conversion, coordinate system conversion & projection conversion, and geometric correction, are described in detail in the perspective of spatial data application. Various spatial data of the study area were integrated using these methods, which laid a solid data foundation for GIS spatial analysis of decision-making. Especially, to resolve problems of transformation between Beijing1954 and Xi'an1980 coordinate system, this paper bring forward an easy and feasible method based on standard frame of topographic map and revised parameters for coordinate. This method operates simply and easily perform, which is very suitable for some persons who don't specialize in survey.(2) High-precision Grid DEM construction experiments were tested, and applied successfully to pre-feasibility research on the Maerdang Hydropower Station on the Yellow River.High-precision Grid DEM construction based on topography data includes two parts, which are optimal production methods choice and best resolution decision. Experimental analysis indicates that:"Topogridtool"in ArcGIS is the best method of Grid DEM generating among common RS and GIS softwares. In view of application targets, topography roughness and profile line length are chosen as quantitative indexes of best resolution decision for Grid DEM generating using different scales topography data, which can overcome the blindness and random in GIS spatial analysis, and ensure the spatial analysis accuracy using DEM."Land Leveling method"was proposed based on DEM theory to calculate the reservoir level-area curve and level- storage capacity curve, which is compiled with C# language into the reservoir area-storage capacity calculation software. By the software, the area and storage capacity of the Maerdang Hydropower Station are calculated quickly, 23.98 km2 and 1.372 billion m3 respectively when the design water level is 3270 m. And the reservoir water level-area curve and water level-storage capacity curve were mapped quickly according to area and storage capacity in different water level.Virtual Reality GIS (VR-GIS) for reservoir region was constructed based on high-precision DEM and high-spatial resolution Quick Bird images, which can provide an important platform for leaders and engineers & technicians to master the project in detail, and assists them regulating and improving project design.(3) Environmental geology investigation and assessment on hydroelectric development was done, which provides objective basis for project decision of the Maerdang Hydropower Station.Regional formation and lithology and linear structures were interpreted using ETM+ images, which can improve regional geological data, repair defects about ground geological work, and indicate direction for engineering geology survey.Reservoir geologic hazards were visually interpreted using Quick Bird images, and the geologic hazards background database was established. Five landslides and five landslips are interpreted in reservoir. Among them, one landslide whose scale is larger, near the down dam and need focus on investigation, the others whose scale were smaller, farther from the dam , slightly affect the project, and mainly bring reservoir sedimentation, which can not constitute restriction elements of project determination and construction.Five evaluation factors, which are slopes structure, slope, formation and lithology, fault and river, are selected to forecast and evaluate the geologic hazard risk of landslides and landslips, based on analytic hierarchy process and the ordinal scale relative weighting-rating technique. Evaluation results are that, geologic hazard risk is moderate in all study area, but that is higher in frontal dam and near dam of reservoir that in the middle part and the tail part. In other words, after the hydropower station established, the probability that landslides and landslips are induced is comparatively bigger. So reservoir shore stability research need to be enhanced in order to ensure the reservoir safely operates after the hydropower station established.(4)Environmental impact assessment of hydropower development was done, which can provide important reference for decision-making of the Maerdang Hydropower Station.Land use types were visually interpreted using Quick Bird images. Based on the theories and methods of landscape ecology, analyzed the impacts caused by reservoir submersion, using nine landscape indexes. After the Maerdang Hydropower Station will been established, it will become a plateau canyon reservoir. Water area will increase 1784.220 hectares, and the reservoir will submerge 938.175 hectares woodland, 405.850 hectares bare land, 368.828 hectares grassland, 71.22 hectares other woodland, and 0.15 hectare residential areas, but cultivated lands and roads will not be submerged, which shows that the Maerdang Hydropower Station will give little impact on the local socio-economic structure, immigration task will be light, and submersion loss will be little.The matrixes of landscape are grasslands before and after submersion, but landscape fragmentation and landscape heterogeneity will rise, and the spatial distribution of the landscape types will become uniform. Comprehensive analysis shows that submersion will give little influence upon ecological environment.This paper evaluated and estimated soil erosion of study area based on RUSLE (Revised Universal Soil Loss Equation). The results show that the level of soil erosion in study area is relatively low, but severe loss areas are mainly located in frontal dam and near dam of reservoir. After the Maerdang Hydropower Station established, sediment from soil loss will directly enter the reservoir. When the Maerdang Hydropower Station designed, we should consider the soil loss will give influence on reservoir sedimentation. The forecast of soil erosion can provide objective basis for the soil and water conservation planning.The application and practice in the Maerdang Hydropower Station indicates that, the spatial information technology (RS, GIS, et al.), which are introduced into pre-feasibility research on hydroelectric project, can complete quickly much work which traditional approaches cannot finish, save labor power, fund and resource greatly, improve work efficiency, and provide powerful technical support for decision-making.