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題名 | Tem Ivestigations of Aquifers in the Ilan Delta, Taiwan=暫態電磁法探查宜蘭平原含水層 |
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作者姓名(中文) | 陳洲生; | 書刊名 | 中國地質學會會刊 |
卷期 | 42:4 1999.11[民88.11] |
頁次 | 頁669-683 |
分類號 | 351.62 |
關鍵詞 | 宜蘭平原; 地下水; 海岸平原; 暫態電磁法; Ilan delta; Ground water; Coastal plain; TEM; |
語文 | 英文(English) |
中文摘要 | 此研究係海岸環境變遷計劃的一部分,以暫態電磁法描繪宜蘭平原地下的電阻率 特性,研究宜蘭平原含水層分佈。暫態電磁法採共圈方式施測,方形線圈之邊長約為 90 公 尺,共收集的測點資料超過 77 個, 涵蓋範圍約為 320 平方公里,施測結果能解析到地下 200 公尺深。測獲資料經一堆平滑模型逆推後,再利用趨勢面分析技術提高資料解讀性。這 些結果以剖面圖及切片圖來展示測區下可能的三維構造。宜蘭平原至少可分為兩種主要的地 下水含水府區域。西宜蘭平原的特性是由高電阻尼的礫及砂所組成,在粗顆粒沈積物之間飽 含淡水。東宜蘭平原之電阻率較低,其含水層屬砂或泥,顯示其受海水入侵,入侵之海水曾 一度到達距現今海岸線 10 公里處。在宜蘭平原的中部區域,其電阻率介於此東低、西高的 兩電阻率之間,顯示此區為兩側沈積物參雜的過渡區域。由此推論,宜蘭平原的形成受控於 蘭陽溪的影響。以上推論經井誌及地質資料證實。 |
英文摘要 | Using the Transient Electromagnetic (TEM) method, the resistivity characters of the Ilan delta, Taiwan, were mapped as apart of an integrated study of coast environmental changes. Coincident loop configuration with square transmitting loops about 90 m on a side was used for this survey. More than 77 soundingswere collected, covering an area about 320 km ��, whose resolutionreached more than 200 m in depth. One-dimensional, smooth-model inversion of TEM data wasused and then trend surface analysis technique was employed torefine the results for interpretation. They were organized intoboth profile and elevation slices for studying possible three-dimensional stuctures. At least, two major hydrogeological units can be visualizedfor the subsurface of the llan delta from this study. The westernpart of the delta is characterized by high resistivity and thick layersof gravels or sands, belonging to fresh-water saturated coarse-grained sediments. In the eastern part, however, the resistivityis lower and subsurface layers contain sand or clay, indicatinghorizons with seawater intrusion, which once proceeded as far as10 km from the present shoreline. In the middle part of the llandelta, the resistivity is between the western high and eastern low, indicating that there is a transition zone. Therefore, it is furtherverified that the formation of the llan delta was predominantly controlled by the Lanyanghsi stream which flows from west toeast. All the above conclusions were checked closely with subsurface drilling and geology. |
本系統之摘要資訊系依該期刊論文摘要之資訊為主。