在僅有單點土壤含水量計觀測的條件下，本研究利用該土壤含水量計觀測與地電阻影像法（electrical resistivity tomography, ERT）推估出區域空間上的入滲範圍分布。本研究於台中霧峰農業試驗所內的一處農地進行二維ERT監測與土壤含水量監測。透過建立現地電阻率變化率與土壤含水量變化率轉換關係式，把富空間解析的電阻率變化率結果換算土壤含水量變化率。進而在一維土壤水平衡的假設下，推估區域範圍中的入滲範圍分布。本研究使用一套全自動多波道地電阻監測系統並採用非傳統的混編陣列定時蒐集電阻資料。在ERT監測期間（2022年6月至8月），我們挑選三個降雨事件進行電阻率與土壤含水量分析。由土壤含水量計所觀測之土壤含水量變化與其對應的電阻率變化，我們建立一線性電阻率變化率與土壤含水量變化率的轉換關係式。其後，我們比較由此轉換關係式計算出之入滲範圍及由土壤含水量計讀值計算出之入滲範圍。因兩入滲範圍結果相近，故我們應用此轉換關係式於土壤含水量計位置之左右各2.5公尺範圍內的電阻率變化率剖面，進而計算該範圍內的入滲範圍分布。根據三個降雨事件的入滲範圍結果，我們觀察到不同土壤材料對入滲深淺有所影響。此外，當降雨量小時，土壤含水量的變化很小，電阻率的變化也很小，在這種訊號–雜訊比低的情境下，我們無法透過轉換關係式將電阻率變化率轉換土壤含水量變化率，並計算出入滲範圍。在僅有單點土壤含水量觀測的條件下，本研究透過土壤含水量觀測與ERT建立現地ERT轉換關係式，最後量化區域空間中降雨入滲所涵蓋的入滲範圍分布。以期此結合ERT與土壤含水量之方法未來對農田灌溉或農田水資源管理上可有所應用及貢獻。;This study presents a method to estimate the spatial distribution of infiltration range in an agricultural land using a single-point soil water content（SWC） sensor and electrical resistivity tomography（ERT）. The research was conducted in an agricultural land at the Wufeng Agricultural Research Institute in Taichung, where two-dimensional ERT monitoring and one-dimensional SWC monitoring were performed. By establishing a conversion relationship between the local relative change in electrical resistivity and the relative change in SWC based on field measurements, the high-resolution results of resistivity variations were transformed into SWC variations. The distribution of infiltration range due to rainfall was subsequently estimated by assuming a one-dimensional soil water balance. A fully automated multi-channel ERT monitoring system was employed, and non-conventional mixed-array configuration was adopted to collect resistivity data at regular intervals. Three rainfall events during the stable ERT monitoring period (June to August 2022) were selected for resistivity and SWC analysis. By observing SWC variations at a single-point location using a sensor and its corresponding resistivity variations, a conversion relationship between the local relative change in resistivity and relative change in SWC was established. This conversion relationship was then applied to calculate the infiltration range within a 2.5-meter range on both sides of the location, based on the calibrated infiltration range and the calculated infiltration range from the sensor records. The results obtained from the three rainfall events indicated that the infiltration range was influenced by different soil materials. However, during periods of low rainfall, when the change in SWC was minimal, calculating the infiltration range through the ERT conversion relationship posed challenges. Finally, despite the constraint of having only a single-point SWC observation, this study successfully employed SWC measurements and ERT monitoring to establish a local ERT conversion relationship, thereby quantifying the distribution of infiltration coverage in the regional space. The combined approach of ERT and soil moisture demonstrated in this study holds promising applications and contributions to agricultural irrigation and water resource management in the future.
