本研究透過兩種保守型示蹤劑1,6-NDS及2,6-NDS，分別於大屯火山區西南部磺溪兩側的5口溫泉監測井進行兩組示蹤試驗，探討溶質傳輸在火山區域含水層之傳輸特性。水樣經高效液相層析儀HPLC分析示蹤劑濃度，建立濃度隨時間變化的穿透曲線，再利用穿透曲線型態進行定性描述及動差法、裂隙模型的定量方法解析溶質在地下的傳輸行為以及其所反映的含水層特性，接著以試驗結果在TOUGHREACT中建立數值模型模擬溶質的傳輸情形來驗證參數合理性。
結果顯示磺溪西側TB-MW-14往TB-MW-6之間存有地下水流快速通道，其示蹤劑穿透曲線皆呈現雙峰分布型態，代表除了以延散作用在孔隙介質為流動通道以外，同時還存在1-2條裂隙通道提供快速的平流作用傳輸；而另一組TB-MW-14和TB-MW-2之間則主要以平流作用在裂隙通道中流動。在磺溪東側TB-MW-16與TB-MW-31之間顯示有許多小裂隙連通的裂隙通道，示蹤劑溶質以延散作用在地下水中傳輸；而TB-MW-16至TB-MW-6之間可能因為磺溪的大量河水導致示蹤劑濃度被稀釋。透過TOUGHREACT數值模擬，以自然水力梯度的流場條件下，模擬以溶質傳輸機制為主，其溶質傳輸需要1000天至25年才能從注入井流到監測井。
Two multi-well tracer tests were conducted with two conservative tracers, 1,6-NDS and 2,6-NDS, in a volcanic area to identify the aquifer characteristics quantitatively and qualitatively. The results show that the breakthrough curves with double-peak accompanied with a strong tailing for the well TB-MW-6 but without the tailing for the well TB-MW-2. It reflects that the existence of advection through a couple fast flow paths of between TB-MW-14 and TB-MW-2; while the advection flow prevailing between TB-MW-14 and TB-MW-6 with a strong dispersion. On the other hand, the results show that diffusion domination between TB-MW-16 and TB-MW-31 in the east side of Sulfur Creek by small fissures connected. A numerical model through TOUGHREACT was constructed and yield the similar conclusion. This study demonstrated how heterogeneity a reservoir can be and the importance of tracer results for understanding the reservoir characteristics.
