一个确定海图基面的方法

TECHNIQUES FOR DETERMINATION OF THE CHART DATUMS

本文提出的一种综合性计算方法,在当地无实测潮汐资料的情况下,直接利用附近测站的调和常数及有关的地形图等资料,完满地求得了珠江口九洲港的论深度基准面。这一方法用在与九洲类似的港口,将具有同样的效果。

This paper presents a synthetic computational method which can produce satisfactory Theoretical Depth Datum (TDD) for Jiuzhou Port in Pearl River Estuary, by directly using the data on harmonic constants and relative topographical charts of the observation stations near the port where the observed tidal data are lacking.In computation, the harmonic constant of each corresponding tidal constituents for Jiuzhou Station are first obtained by means of 'Geographical Interpolation Method' on the basis of the harmonic constants and topographic conditions at Xiangzhou and Dongaodao Islands Stations. Then the formula of 'Indian Spring Low Water' is adopted to compute' Nearly Lowest Low Water' for the above three stations, as the characteristics of the diurnal constituents is notable in this sea area. With knowledge of the relations between TDD and Mean Sea Level at Xiangzhou and Dongaodao Islands Stations, 'Nearly Lowest Low Water' for Jiuzhou is then corrected to work out 'Approximate Lowest Low Tidal Level', which is regarded as an important collateral evidence to determine the TDD for Jiuzhou Harbour. Meanwhile, the 'Theoretical Possible Lowest Low Water' for Jiuzhou Station is obtained through the computation of the two combination of 8 and 11 tidal constituents. Finally, the all-computed characteristic lowest low tidal levels are compared; thus TDD for Jiuzhou is determined to be a reasonable value below the Mean Sea Level.This method is expected to be valid for ports similar to Jiuzhou.