Journal of Geo-information Science >
ParallelWatershed Codification Algorithm Based on Pfafstetter Coding System
Received date: 2014-12-26
Revised date: 2015-02-01
Online published: 2015-05-10
The research approach based on sub-watershed partition, which is taken as an indispensable tool of spatial analysis in GIS applications, plays an important role in many research fields of watershed, such as landform, soil, hydrology and environment. Watershed codification usually is a key step in the research process via the above approach. Compared with some other watershed codification methods, Pfafstetter coding system is widely adopted due to its uniqueness of code, consideration of topological relationship and high efficiency. At present, with the development of spatial data acquisition technology, the quick acquisition of spatial data from large areas and with fine scales becomes a solid reality, which brings a great difficulty to GIS on how to process and analyze these massive datasets quickly and efficiently. Parallel computing brings an opportunity to face this challenge with the development of computer technology. In this paper, a parallel watershed codification algorithm was proposed to overcome the computation difficulties in processing the massive grid dataset. Firstly, the Pfafstetter coding rule was modified to compensate the disadvantages in the original algorithm including the incomplete coding and inconsistent code point. Secondly, data partition and parallel strategy were discussed based on the serial Pfafstetter coding algorithm and the requirements of data parallelism. At last, the parallel algorithm for watershed codification was realized and implemented. To evaluate the validity and the efficiency of the proposed parallel algorithm, experiments were designed on a cluster system with SRTM dataset covering the middle and upper watershed of Yangtze River. The experiment results showed that the parallel algorithm could generate correct results which were consistent with those in the real world; meanwhile, it possessed a significant improvement of computational efficiency. Besides the advantages in improving the computation ability and efficiency for the watershed codification algorithm, the parallel strategy in this paper could be further expanded as a reference to other researches on watershed analysis.
Key words： Pfafstetter coding system; parallel computing; DEM; watershed codification
WANG Chun, JIANG Ling, CHEN Taisheng, YANG Cancan . ParallelWatershed Codification Algorithm Based on Pfafstetter Coding System[J]. Journal of Geo-information Science, 2015 , 17(5) : 556 -561 . DOI: 10.3724/SP.J.1047.2015.00556
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