Research On Theory, Technology And Application Of Construction Of Digital Watershed

Digital watershed was epitome of digital earth, digital china, digital Loess Plateau, was an extended impression of digital Loess Plateau, was a concrete embodiment of theory, technology, stratagem of digital earth applied in communicatization, intelligentization and sustainability in watershed. The paper analyzed feasibility of construction of digital watershed, directed by conception of digital earth, by means of 3S, 4D. Theory, technology, and way of realization of digital watershed were discussed primarily. Summarizing research results of personnel of the task group, combining with my research on theory and application of watershed spatial database, mapbase, spatial data basic frame, we put forward construction pattern and realization way of digital watershed, tried the construction and application of digital watershed primarily. Research results were as follows:1. Digital watershed was epitome of digital earth, based on elementary theory of digital earth and many years' work foundation of the watershed, stemming from watershed informationalization construction, function, structure, system, configuration, development stages were conceived. Meanwhile, technological means of theory and fulfillment of digital watershed construction from many facets such as main frames, data types, constitution and structures were explored preliminarily.2. Taking Mapgis as basic plat, digitalization of watershed information was fulfilled. Using land resource units as basic geographical unit in order to integrate watershed digitalization information, acquiring theme attributes of basic information by means of attribute table manipulation, watershed basic information database was constructed. During research, many key technique such as data obtainment of digitalization and construction of base, quality control, confirmation of basic information unit plot were explored for many times. Practice proved that research means adopted were completely advisable for construction of digital watershed.3. When database was built, taking land resource unit as geographical unit for watershed data integration, we analyzed in piles land resource unit map and single element map layer of every evaluation factor, acquired attribute data through manipulation on attribution file of produced map layer. Results showed that, attribute data obtained by this way avoided deficiency of polygon overlap way, as a result, the logistical consistency between map data and attribute data reached over 90% on average. Database pivot precision was 0.18mm, data quantity during manipulation was decreased greatly, data treatment was more convenient, computation velocity was boosted greatly. Workload of map and table pretreatment and edition was mitigated on large scale, spatial data precision was increase.4. On grounds of theory and construction foundation of spatial data framework,watershed spatial frame basic data was confirmed. Watershed spatial basic framework was erected, DOQ being taken as foundation data, utilizing screen digitalization technique to distill main vector lineal element. Taking engineering as unit, united spatial base being supplied, vector-grid basic spatial data was managed wholly. Watershed land use condition was updated swiftly, watershed land use status map was made, through vector-grid overlap of land use status map and DOQ, distillation characteristic data and updating data.5. MapGIS being taking as basic plat, based on watershed information accumulation, watershed land resource map analysis was carried out on shape and structure on grounds of elementary theory of land resource. Aided by SPSS software, principal analysis and clusters means was utilized to evaluate watershed's land quality hierarchy. Experiment of combination of GIS and subject model was made, to provide scientific foundation and technological support for watershed synthetic management and planning.