已最低天文巢位面為臺灣海圖基準參考探討

Discussion of a Surveying Problem：The Triangle Area and Side

「航海」與「海運」是人類的重要資源與產業，「海圖」是以航海為應用目的之圖資，其建置也是政府施政中的基本項目。「海圖基準」是製作「海圖」時所依循之「垂直基準」，因此也是國家重要測量基準中一項。臺灣現行之海圖基準，採用「約最低低潮面下」，國際的現況是推動使用「最低天文潮位面」作為海圖基準設定之參考潮位面。本文嘗試探討現行基準之優劣點，並敘明採用「最低天文潮位面」之原因。

Navigation and marine transportation are important resources and business sectors. The objective of the chart is for navigation with the establishment of a set of operational charts an essential part of infrastructure. Chart datum provides the vertical reference surface for the mapping of the chart and is one of the fundamental datums for a country. The current chart datum of Taiwan is based on the Approximate Lowest Low Water (ALLW); while the Lowest Astronomic Tide (LAT) is the commonly recommended reference by international associations. This article reviews the pros and cons of ALLW and the reason for adopting LAT.