Research And Application Of The Drainage Extraction Method Based On Geoprocessing Service

DEM-based drainage extraction is a hotspot in digital hydrology research. At present, DEM-based drainage extraction has integrated in lots of traditiona commercial software. The processing process in this commercial software is straightforward, but it need to purchase the appropriate software and would carry out the inadequate to the network resource utilization while it’s operated based on the the stand-alone environment.This thesis probes into the key technologies of geoprocceing service and DEM-based drainage automatic extraction through processing service. Studies using geoproccing service to realize drainage automatic extraction in the network environment and taking Jiulong river basin DEM as an example to validate the method of drainage extraction based on geoprocessing service. Content and contribution of this thesis are presented as follow:1) The key technologies of geoprocesssing servicesThe concept of geoprocessing and geoprocessing services were expatiated and the key technologies of the execution mode, state management, granularity and interface access mode of geoprocessing services were discussed. The contributions of this discussion are presented as follow: in the the complex geoprocessing process environment, asynchronous execution, pooled state management, coarse-grained and the REST interface is more suitable for complex geoprocessing services.2) The method of drainage automatic extraction based on geoprocessing serviceResearched the method of drainage extraction based on DEM and built the model of drainage extraction. This including four procedures:the preprocessing of DEM, the calculation of the flow direction, the calculation of the flow accumulation and the generation of river network. Analysis of how to publish the geoprocessing model to geoprocessing services and probed into the method to call geoprossing services in the network environment.3) The analysis and evaluation of Jiulong river basin DEM-based drainage extractionTook 30 m resolution DEM data of Jiulong river basin as example, the reliability of the method of drainage automatic extraction based on geoprocessing services has been validated. Used quantitative and qualitative analysis method to contrast GP-based drainage extraction result and reference water system. The comparison of GP-based drainage extraction and actual water system showed that using this GP-based DEM drainage extraction method to extract the drainage of Jiulong river basin in general can objectively reflect its space distribution.