礁溪溫泉是台灣重要的溫泉區之一，溫泉區日漸發展，溫泉旅館快速增加，溫泉水資源的使用與管理，面臨極大的挑戰。研究指出本區溫泉已經超抽，並導致溫泉分布範圍縮小與溫度降低。然而，因缺乏長期水位與水溫的監測數據，本區溫泉的成因、是否已過度抽用？仍無法定論。因此，為了瞭解現今溫泉區之狀況以及未來的永續發展，需要建立起此區之長期資料庫。
本研究藉由井溫剖面的量測，水文地質鑽探等資料綜合整理，提出一較具體的溫泉生成模式。並設立四個監測站，監測水位及水溫，以瞭解溫泉水資源的長期變化。
礁溪溫泉的來源為西測坡地下的四崚砂岩，熱水由砂岩裂隙上湧，進入上覆的沖積層後，向下游呈水平流動。熱水分布呈西北－東南長、東北－西南窄的長條形，軸長約1.5km、寬約1.0km。此沖積層在溫泉中上游厚度約20－100m，往東南變厚可達200m。由上往下約可分三層，上下以礫石層為主、中間夾中細砂層。
礁溪溫泉的主要用水層次為地面下20－50m深，此層之水位由西北往東南漸次降低。水位變動與降雨有明顯的相關，2008年9月降雨超過1000mm，水位上升即達1－6m。沖積層的溫度上下兩層較冷、中段較熱，推測因中段為主要抽水層次，人為抽水致使熱水較快補充。此主要熱水層之水溫由西北往東南漸次降低，源頭約65℃、中游55℃、下游45℃。
2007年8月至2010年1月、共二年半的監測，並沒有發現水位或水溫降低；相反的、太子井及國小井的水溫都有微升，推測溫泉井大量的抽熱水，對淺部地層有加熱作用。 The Jiaosi hot spring is one of the most important hot spring destinations in Taiwan. The hot spring water resource meet great challenge for an increasing development of hot spring resorts in decades. Studies showed that hot water had been extracted in excess of its recharge to the aquifer and the overpumping had caused the hot water front retreated and temperature declined. However, there is no long-term monitoring data to prove the time and magnitude of those overpumping events. Therefore, to understand the current situation and the future of sustainable development of Jiaosi hot spring,we need to build long-term of this area database.
For understanding the occurrence and movement of hot spring waters, we compile a hydrogeological conceptual model from driller’s logs and by measuring the temperature profile in wells. We also install probes in four wells to monitor the water levels and temperatures.
The quartzite in the west hillside is the source of hot spring waters which flow upward along fractures and enter the horizontally unconsolidated sedimentary aquifer, then flow mainly to the southeastern. There are three layers in the aquifer, upper and lower gravels layers and middle sand layer. Thickness of the aquifer is about 20-100m in the northwestern upflow area and over 200m in the downflow area. The hot waters distribute over the aquifer with a surface area of about 1.5×1.0 km2.
There is a significant correlation between water levels rise and rainfall intensity. In September of 2008, the water levels in hot spring wells raised for several meters while the rainfalls were over 1000mm. The temperature of the middle layer is higher than the upper and lower layers and indicate the middle layer has been pumped intensely. According to our data, we suggest that there is no hot water front retreated or temperature declined during the monitoring period of two and half year.
