| 摘要: | 本研究利用電阻率成像法（Electrical Resistivity Imaging, ERI）探討淺層古河道特徵，以判 定宜蘭平原的地下水位（Groundwater Level, GWL）及水文地質系統。共佈設十條測線， 採用Wenner 佈極方式，電極間距為 2 公尺，測線長度介於 80 至 100 公尺之間。電阻率資 料經由 AGI EarthImager 2D 軟體進行反演，生成二維反演電阻率模型。選取的垂直反演電 阻率點被轉換為土壤含水特徵曲線（Soil-Water Characteristic Curves, SWCC），並利用 Van Genuchten 模型的經驗關係式計算地下水位。測勘工作於 2024 年 4 月、9 月、11 月及 2025 年 2 月四個時期進行。結果顯示，YN8 測線的地下水位最高（約 12.9 公尺），而 YN1 與 YN3 測線最低（約 3.0–3.4 公尺）。為驗證地下水位推估結果，本研究比較了四口 觀測井資料：同樂井（Tongle）介於 8.4–10.3 公尺之間、ZTE 井最低（4.1–4.8 公尺）、大 寅井（Dayin）最高（26.0–32.0 公尺）、紅柴林井（Hóngcháilín）介於 15.8–16.3 公尺之間。整體地下水流向由西南側補注區向東北側排泄區流動。綜上所述，本研究證明ERI 技術在 資料稀缺地區可作為評估季節性地下水變化的高效且經濟的方法。同時，研究結果突顯古 埋河道對現今地下水流動的長期影響，為未來水文地質評估提供了寶貴的參考。
;This study investigates the shallow paleo-channel features using Electrical Resistivity Imaging (ERI) to determine the Groundwater Level (GWL) and hydrogeological system in the Yilan Plain, Taiwan. Ten ERI survey lines were set up utilizing the Wenner Array with a 2-meter electrode spacing across profiles measuring 80 to 100 meters length. The resistivity data were processed using AGI EarthImager 2D software, which generated 2D resistivity inversion models. Selected vertical inverted resistivity points were converted into soil-water characteristic curves (SWCC), and GWL was calculated using empirical relationships through the Van Genuchten model. Surveys were carried out across four periods: April, September, November 2024, and February 2025. Among the lines, YN8 showed the highest GWL (up to 12.9 m), while YN1 and YN3 represented the lowest (3.0–3.4 m). To validate our GWL estimates, data from four observation wells were used. The Tongle well ranged from 8.4 to 10.3 m, ZTE had the lowest level (4.1–4.8 m), Dayin showed the highest level (26.0–32.0 m), and Hóngcháilín ranged from 15.8 to 16.3 m. The groundwater flow was from the southwest (recharge area) toward the northeast (discharge zone). In summary, this study demonstrates that ERI offers a cost-effective approach for assessing seasonal groundwater variations, particularly in data-scarce areas. The results also highlight the lasting impact of ancient buried river channels on present-day groundwater flow, providing valuable insight for future hydrogeological assessments. |
