Among the Digital Land Information files organized by Geographical Survery Institute, the data of river systems in Japan is supplied in three volumes of relational data files as KS-606, KS-270 and KS-271 (Table 1).
The author made a concise and practical data set from those files for the purpose of drawing the river bed profiles. This data set is self-defined, and has the control information as to upstream/downstream linkage, the identifier of individual river system and the value of the pseudo-'stream order' (Table 2). This article reports the process and its logic to generate these attributes, referring the former analysis on the original data set.
This generating process was performed by the 'reformer' and the 'linker' shown in Figure 4. The reformer, first, re-constructed the linkage data of the KS-271 file through the selection of the river-mouth of the trunk (Figure 3c). The linker framed the logical river systems by writing the pointers on each record, and masked the channels which should be ignored (Figure 3d). Through the following passes of the linker operation, the individual river systems were identified from each other, and the 'stream orders' were calculated to recognize partial river systems.
A sample printout utilizing this data set is shown in Figure 5.