GIS-based Study On ChangJiang Estuary Spatial Decision Support

There are two main traditional methods in the research of Changjiang Estuary: mathematical model and physical model, by which problems are both analyzed and calculated according to the existing knowledge. They are deductive courses, in which much implied knowledge cannot be discovered. SDS can deal and transform spatio-temporal data with spatial analysis methods, so that knowledge implied in the spatial data can be extracted by maps or tables. It mainly belongs to an inductive course, which is much effective supplement to the traditional methods. Reality of based-GIS SDS in Changjiang Estuary research fields may widen its research methods further, and it will be much significative.Based on the summary of the actuality and characteristic of current research data in Changjiang Estuary, this Paper discussed and solved four key problems in Changjiang Estuary SDS in the round by the component technique which is consisted of C# and ArcGIS.Using object-oriented methods, this paper integrated spatio-temporal data model with Geodatabase model, studied the modeling problem of Changjiang Estuary spatio-temporal data, and realized the unification of existing data. so that existing data in different formats can be used in a unite system, in which spatio-temporal data can be expressed directly, not only in many different formats such as MapInfo and Shapefile, but also from relation database. Based on the data modeling timely spatio-temporal analysis can be maken according to requirement.This paper summarized the action of spatial metadata in the Changjiang Estuary Research, discussed the content and technique of Changjiang Estuary spatial metadata, and made the construct of Changjiang Estuary metadata modeling.At the same time publishing of Changjiang Estuary spatio-temporal data was realized based on ArcIMS, including the functions of reference, browse and download.SDM is one of the kernel modules of SDS, being the principal part of its model base. And different problems can be solved with different SDM techniques. This paper set up three application models: it studied on the affection on cutting and filling in the estuary by upriver hydrographic feature using Rough Set theory, which can mine the relationship. between sediment concentration and Runoff at Datong station and downstream cutting and filling; Using geostatistical methods, it made the correlation analysis on the sediment concentration and salinity data of 12 stations measured nearby Changjiang estuary in the flood season of 2004, by which the spatial correlation among these data can be found; Using spatial cluster analysis, it studied on the change exhibition of cutting and filling in Jiuduansha in the same season among 1995, 2000 and 2001 .And this change can be expressed with dynamic map.The application of based-GIS visualization technique in Changjiang Estuary was studied, which is embodied in three aspects: data exploratory analysis, spatial data quality inspection and terrain dynamic displaying. This paper studied on the two latter applications, realized the quality inspection of digitized terrain data and measured hydrographic data in order to heighten the accuracy of research data, and realized the switch of three different modes of displaying digital terrain and dynamic displaying different terrain features.These aforesaid research widened the methods of Changjiang Estuary studies setting up corresponding system of SDS, and solved the key problems, which made it possible that SDS techniques be applied in Changjiang Estuary studies .