宜蘭的噶瑪蘭廳在1810年代築起城牆、鑿溝壑為護城河。清末到日治，隨著市街發展與商業活動，城牆與護城河成為阻礙，因而在都市計畫下逐漸消失於地景之中。噶瑪蘭城與城內空間考證已有前人進行詳細的探討，然而護城河的資料卻只能在噶瑪蘭城的考證文章中窺見片段，難以找尋它的完整故事。護城河水源從哪引入，又從何處匯入宜蘭河？護城河在市街變遷中的身分經歷哪些轉變？又從何時消失於的城市地景中？這些都是有待釐清的議題。
本篇首先從《噶瑪蘭廳志》中的紀錄尋找護城河出現之前的水圳道路以及水的流向，接著以《宜蘭城略圖》、《宜蘭郵便電信局市內略圖》、《臺灣堡圖》、《宜蘭街市區改正圖》等大比例尺地圖為參考。再綜合市區改正、埤圳加蓋等公共工程記錄，以及歷史新聞等文獻，拼湊出噶瑪蘭城市街發展過程中，由環城的溝壑變為景觀水圳，最後完全消失的過程。本文運用大量地圖史料來還原護城河的空間歷程，提示了宜蘭市街發展中常被忽略的重要環節。藉由兩世紀以來噶瑪蘭城護城河的空間探索，除了提供更完整的鄉土研究成果，也可做為地方政府在都市景觀工程之重要參考。

The Kavalan offices build the walls and the moats of Yilan areas in 1810s. As time goes by, it became obstacles for the street expansion and the commercial development during the transfer of governance power between the Qing Dynasty and the Japanese colonial government. Finally, the modern urban planning gradually eliminate the landscape of the Kavalan city walls and the moats. The construction of the walls and the institution allocation inside the city had been well discussed in the previous studies, but the description of the moats remains the lost fragment in the spatial narratives of the city. Some study issues can be rise as: where the water came from and where to outflow; the change of the Kavalan city moat's identity during the last century; when and how each part of the moats disappeared in the landscape of the city.
In order to solve the above mentioned issues, we first identify the flow of water ways and the irrigation canals before the appearance of Kavalan moats with the reference of “Kavalan Prefecture Chronicles (噶瑪蘭廳志 )＂. Then, we overlay a series of large-scale maps including the “Yiland Town's Overview Map (宜蘭城略圖)＂,“Yiland City's Postal telegraph Summary Map (宜蘭郵便電信局市內略圖 )＂,“Taiwan Bao Map (臺灣堡圖 )＂, and “Yiland City's Amendment Map (宜蘭街市區改正圖 )＂as references to contrast the historical documents related to the river improvement, sewer development and the urban planning. Thus, we frame a complete story of the Kavalan city moats from a protection function to a sightseeing river, then covered by the road and disappeared in the memory of citizens. In this study, we represent the spatial process of the change of the Kavalan city moats that effectively fills up the missing link of the development of Yilan city. By the long term investigation of the Kavalan city moats during the past 2 centuries, it also provides important references for local government's urban landscape projects.