臺灣地形特徵圖繪製之研究－以木柵圖幅為例

Abstract

地形特徵圖(geomorphological map)是許多國家彙整地形訊息，以及進行自然災害或土地管理的重要工具，但是臺灣在這方面的發展有限。本研究之主要目標為探討現階段臺灣進行地形製圖的可行方案，具體目的包括：回顧各國的地形製圖(geomorphological mapping)經驗；評估國內各項環境類圖資與需要調查的地形資訊；以焦點團體訪談方式了解地圖使用者的意見。本研究之樣區為1:25,000經建版地形圖之木柵圖幅的範圍；地圖使用者則指地形、地質領域以外的相關專業人士。 本研究回顧義大利、日本、瑞士及Gustavsson et al.(2006)製作的地形特徵圖。其中以義大利地形特徵圖系統參考價值最高，圖上完整展現地形特徵(morphography)、地形計測(morphometry)、地形生成作用力(morphogenesis)、地質資訊/岩性(geology/lithology)、地形年代(morphochronology)、地形動態(morphodynamic)等多種地形製圖要素，且文獻也較為完整。盤點國內已經建置的各式環境資料庫和圖層，發現崩壞、土石流地形與數值地形模型可直接應用於地形製圖，但多數地形單元還缺乏全台有系統性的資料及圖示呈現。而根據焦點團體訪談結果發現，模擬地形立體感的表現方式，包含主圖使用陰影圖為底圖或插圖中的立體地形圖，皆獲得肯定。而為提升主圖易讀性與保存整體資訊的豐富度，原在主圖的岩性圖層改以插圖方式呈現，以降低主圖複雜性。 本研究以1:25,000木柵圖幅為例所進行的分幅地形特徵圖繪製嘗試，涵蓋製圖前期的地圖樣式決定，中期的地形資料蒐集，以及後期根據地圖使用者所做的調整，此歷程可提供未來發展全台分幅地形特徵製圖工作的重要參考。必須說明的是，當研究時間或必須在短時間製圖完成時，採用既有圖資不失為一可行的策略，不過地形基礎研究是地形製圖的基礎，未來須有更多地形專業工作者投入，以建置更為完整的地形資料庫。

Many countries have published geomorphological maps for the purpose of landuse planning or hazard management. However, such work is largely ignored in Taiwan. Hence, this research intends to construct a 1:25,000 Muzha geomorphological map for the first time. The main objectives include: (1) to review geomorphological mapping system in various countries, (2) to evaluate the existing environmental datasets for mapping, and (3) to collect different map users’ opinions about the geomorphological map through group interviews. Four geormorphological mapping systems reviewed include that of Italy, Japan, Switherland, and Gustavsson et al.(2006), The geomorphological map of Italy consists of the most complete information, including morphography, morphometry, morphogenesis, geology/lithology, morphochronology, and morphodynamic. It is found that various datasets of geological hazard and digital terrain model (DTM) are available in Taiwan, including those incorporated in the Susceptibility maps of mass wasting and debris flow, and to a less extent, fluvial terrace. However, the datasets of many characteristic landforms of various geomorphic processes are not available in a systematic way. Through the group interviews of non-geomorphologists/geologists, potential map users recoken, it is found that hillshade map or 3D map are easier to read than the contour map. Information such as geology and lithology is better to be presented in the inset maps rather on the main map to increase the readability and preserve the information abundance. In brief, this research provides an overall workflow of geomorphological mapping which is applicable in Taiwan, with the example of Muzha. It will benefit the work of constructing geomorphological map series in the future.