Study On The Numerical Calculation Key Techniques And Its Applications Of The Hydrologic Map

Today is an information era with the characters of digitalization and computer application. Straightly analyzing, processing and expressing the hydrological variation and their laws in spatial distribution have become a developmental trend of hydrological science. However, traditional numerical calculation of the hydrologic map is low in automatous level and high in generalizer, can't satisfy the further development of hydrological science. It is urgent to improve the key techniques of the numerical calculation.The theories of map algebra, mathematical morphology and digital image analyzing were integrated, the science and techniques of computer in morden times were used, and the numerical calculation key techniques of the hydrologic maps, based on the characteristics of hydrologic maps, were lucubrated in this thesis. The main findings in this thesis are as follows:(1) Through the algebraic analyzing of the hydrologic map and the analysis and processing of the digital image, one could learn the knowledgement of the electronic map and digital image.(2) The deficiencies of the existed gridding project were indicated, and another project which combined with the potential characteristic information in the hydrologic map was promoted.(3) One arithmetic of skeleton extraction, which aims at the images that have a spatial distribution patten and integrated the morphological skeleton extraction model and the nature of the morphological arithmetic, was designed here. Skeleton extracted here with exact position, well connectedness, single pix width and little noises, which can well express the spatial distribution of the hydrologic map's characteristic factors.(4) The automatic linear interpolation was achieved. Based on the steepest slop interpolation arithmetic that presented by Leberal and Olson (1982), some improvement were made here by combined the distance transform, connective region extraction, golden section, introducing an buffer and making the polygon line to approach the steepest slop between associated isolines and the characteristic points, from which greatly heighten the precision and efficiency of the results of the linear interpolation(5) The gridding's steps of the electrical hydrologic map, the problem of coordinate transformation between geography and row-column, evaluation of digital isoline were described in detail. Furthermore, the different kinds of factors which might influence on the precision of the gridding result were discussed.(6) Comparing the isoline revivification, detailing, section analysis and 3-d images of the gridding result, from which indicated that the gridding project of hydrologic map is reasonable in this thesis.(7) Taking advantage of the isoline maps of the mean precipitation, the variation coefficient and the linetype of P-III hydrologic frequency distribution, the grid maps of design storm were given. Its precision basically comes up to the newly complied Chinese Rainstorm Statistic Parameter Atlas.