Fast Computation of Designed-discharge of Sewage Pipe System under GIS Environment

As a key stage in planning and designing the urban sewer system,computing the pipeline designed-discharge is very critical and time-consuming to the planner and designer.Traditionally,there are two problem-solving alternatives,i.e. the artificial tabular computation and the programming computation.It is obvious that the efficiency and precision in tabular method is very low,and high efficiency may also be impossible with programming method if no well-defined data structure and data models are employed.With the rapid progress and wide application of geographic information systems(GISs),however,an advanced GIS-based technique breeds new approaches.In this paper,we use GIS as the basic supporting environment and present an analysis model for fast computation of the pipeline designed-discharge in which a recursive algorithm is involved.The algorithm is based on a so-called chained list composed of nine items whose major initial contents are transfered directly from the arc attribute table(AAT) arranged by ARC/INFO,one of the famous GIS softwares.Also,the recursive principles,the establishment of the chained list and the implementation of the recursion,etc.are analyzed in detail.Meanwhile,an example is given to view the recursive procedures.