臺灣桃園市觀音區至新屋區海岸有臺灣地區發育較為完整且面積廣大之藻礁分布，本區大部份礁體早期為珊瑚礁發育，後期則以殼狀珊瑚藻為主要造礁生物，其生態系具有相當的獨特性，且動物棲息之密度極高，因此亟需就地進行保育。地電阻影像剖面探測技術為一施測快速且非破壞性之地球物理方法，由於含水礁體較其它地層具有更低電阻率之電性特徵，因此常應用於生物礁之相關探勘。本研究為國內首次應用地電阻影像法於桃園海岸生物礁之研究，其目的為藉由地電阻影像法尋找生物礁之分布範圍及深度，以在不影響礁體本身與其周遭生態之情況下，求得調查區域之生物礁分佈空間型態，及其與上方砂泥沈積物或其下方礫石層間之分層與接觸關係。本研究首先探討不同地電阻陣列與逆推計算方法對於地下構造的解析度，比較從原始資料取得放電時ΔV/I值之不同計算方法，並將結果應用於觀音海岸生物礁地電阻調查與研究資料處理。研究區域為桃園觀音區海岸富林溪南岸至觀音溪南岸之沿海區域，共有三條平行海岸線各960米長，與一條垂直海岸線長230米之地電阻測線。施測所得之電阻率剖面以阿爾奇定律為基礎，參照鑽井地質資料、砂樣試驗分析與透地雷達剖面以定位地電阻剖面中覆砂、礁體與礫石層之分層位置。本研究所得調查區域之礁體分布深度為0-1.5米（上方為砂層）至4-6米（下方為礫石層），另於最南邊測線之礁體層於末端一百米有愈來愈薄之趨勢，應為接近本研究調查區域之生物礁分布邊界。;The biological reefs located along the coastal line of Guanyin and Xinwu districts in Taoyuan city is consisted of algal reefs and coral reefs, and also regarded as a big and complete biological reef area in Taiwan. Algal reefs build up extremely slow and expand only 0.9 to 2.3 mm every month; as a result, any investigation in the algal reef area must be implemented very carefully to reduce potential influence in the environment. Because of special electrical property of reefs, it is suitable for applications of electrical exploration methods. The Electrical Resistivity Tomography (ERT) is a fast, non-destructive, and inexpensive surficial geophysical survey method, and therefore it is widely used to investigate reefs. In this study, the location, distribution area and depth of algal reefs were investigated by ERT method to provide a reliable reference of coastal engineering and the establishment of ecosystem refuge. The study area is from the south coast of Fulin river to the south coast of Guanyin river. There are four ERT survey lines, three of them are 960m long and parallel to the shoreline, and the other one is 240m long and perpendicular to others. According to the Archie′s Law, the porosity was calculated from the resistivity profile to estimate the depth of reefs beneath each survey line and verify the estimates with the data obtained from borehole core. The results show that the upper boundary of the reefs is 0-1.5m deep (there are sands layer above), and the lower boundary is 4-6m deep (there are conglomerates layer below) in the study area. In addition, all profiles obtained from the north-south survey lines show that the depth of reefs becomes shallower in the range of 100 m in the southernmost end, indicating the southern boundary of the reef distribution in the study area.
