摘要: This paper studies urban waterlog-draining decision support system based on the 4D data fusion technique. 4D data includes DEM, DOQ, DLG and DRG. It supplies entire databases for waterlog forcast and analysis together with non-spatial fundamental database. Data composition and reasoning are two key steps of 4D data fusion. Finally, this paper gives a real case:Ezhou Waterlog-Draining Decision Support System (EWDSS), with two application models, i. e., DEM application model, water generating and draining model.