Utilize Heat as a Tracer to Study the Characteristics of Groundwater Flow and Hydrological Cycle in Alpine Hydrogeology

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Project title

Code/計畫編號

MOST109-2116-M019-002

Translated Name/計畫中文名

高山水文地質環境之水文特性、交互作用及水文循環 – 以七家灣溪流域為例-以熱示蹤劑方法研析高山水文地質環境之地下水流動特性與水文循環

Project Coordinator/計畫主持人

Yung-Chia Chiu

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Institute of Earth Sciences

Website

https://www.grb.gov.tw/search/planDetail?id=13540304

Year

2020

Start date/計畫起

01-08-2020

Expected Completion/計畫迄

31-07-2020

Bugetid/研究經費

2053千元

ResearchField/研究領域

地球科學

高山中的地下含水層在高山集水區系統中扮演非常重要的一環，然而受到複雜的地質條件影響，其流動不再遵循傳統的孔隙介質理論，至今尚未有一理論基礎可用以完整的描繪高山水文地質（alpine hydrogeology）系統之水文特性及水文循環。此外，隨著水資源的日益匱乏，整體水資源儲量大幅減少，在政府提倡多水源多系統聯合經營區域性水資源策略下，尋找替代水源並兼顧環境保育及資源永續利用為一重要課題。有鑑於此，針對山區水文地質的調查，投入人力與經費資源勢在必行，透過對高山河川與地下水之交互關係、裂隙岩體之地下水流動路徑與水力特性及崩積層與裂隙岩體之地下水蘊藏量等調查，建構屬於台灣的高山水文地質概念模式，藉此掌握山區的水文特性、交互作用、水文循環、演變過程及地下水蘊藏量，提供未來在因應氣候變遷與土地利用改變下水資源調適策略的參考依據。本專題計畫為整合型計畫之子計畫一，主要目的為藉由創新的高解析度分散式光纖溫度感測器量測技術（fiber optic distributed temperature sensor, FO-DTS），以熱能為地下水示蹤劑之方式，進行現地長期監測與試驗，研析高山地區地下水與一級河川間之交互作用，並針對高山地區之岩體進行透水裂隙調查，嘗試建立高山水文地質系統之水文循環及概念模式。研究場址選定為雪霸國家公園內之七家灣溪流域。第一年度的工作為FO-DTS的現地河川水溫量測工作，判釋河道中地下水入滲及出滲區段，區分深層地下水與淺層伏流水，研析河道型態、河床幾何形狀對於交互作用之影響，解析河水與地下水(或伏流水)之交互作用。第二年度的工作為FO-DTS的井下量測工作，藉由特殊設計之光纖加熱系統及自製設計之超高解析度纏繞光纖，判釋井下岩體之裂隙位置分布與透水性，建立優勢水流路徑，研析裂隙岩體系統之地下水流動。第三年度的工作為透過新設置於河道旁坡地之井進行試驗，研析垂直方向之水流交換行為及坡地側向地下水分析，建立高山水文地質在垂直方向(土壤-崩積層-裂隙岩體)之水流交換行為及坡地側向地下水流分析。本計畫之最終目的為彙整子計畫二與子計畫三之成果，透過對於高山水文地質特性的研析及水文循環的探討，初步建構高山水文地質概念模式，而此具有科學理論基礎之概念模式可提供後續氣候變遷與土地利用改變對於高山水文地質環境之影響與反饋分析。The mountainous aquifer plays an important role in the alpine watershed system. The groundwater flow in the system do not follow the traditional theory of porous media because of the complex geological conditions. A comprehensive theory to describe the hydrological characteristics and water cycle in alpine hydrogeology up-to-date still does not exist. The serious scarcity of water resources and significant decrease of water storage enforce the government to promote the idea of conjunctive use strategy of multiple water resources and consider the environmental conservation and sustainable water usage simultaneously. Accordingly, the detailed investigation of hydrogeology in the mountain area with plenty of manpower and funding is desired. Through long-term monitoring, field experiment, theoretical analyses, and numerical simulation, the conceptual model of alpine hydrogeology can be developed to evaluate the stream and groundwater interactions, groundwater flow paths in fractured rock, and potential groundwater storage in regolith and rock. The model can also be used as a reference tool to evaluate the impact of climate change and land use alteration on water resources and adaptation strategies. The proposed three-year project is the subproject#1 of the integrated research project. The purpose of subproject is utilizing heat as a trace with the technique of fiber-optic distributed temperature sensor (FO-DTS) to evaluate the interaction between first-order alpine stream and groundwater, identify the permeable fractures and characterize its hydraulic property. The goal is to develop a hydrogeological conceptual model to describe the flow path and water cycle in the alpine system. The experimental site is selected at Chichiawan Watershed in the Shei-Pa National Park. In the first year, the work will focus on the measurements of stream temperature using FO-DTS and the identification of groundwater recharge/discharge locations along the stream reaches. The groundwater and hyporheic inflows will be distinguished and the effect of stream morphology on the interactions will also be addressed. In the second year, the work will focus on the measurements of temperature profiles in the deep boreholes using customized fiber cables with the heating pulse control system and wrapped super-high resolution cables. The permeable fractures will be identified and the preferential flow in the fractured rock will be developed. The water exchange within the fractured rock will also be evaluated. In the third year, the work will focus on the measurements at the new drilling boreholes located at the river bank. The horizontal and vertical groundwater flow paths will be evaluated through the measurements and water exchange within the soil-regolith-rock system will be analyzed. The lateral groundwater contributed from hillslope will also be addressed. The ultimate goal of this project is to aggregate the outcomes from this subproject with other two subprojects, i.e., #2 and #3, to comprehensively study the hydraulic characteristics and hydrological cycle in alpine hydrogeology. The preliminary 3-D conceptual model will be developed and provided for the further feedback analysis of the impact of climate change and land use alteration on the alpine hydrogeology environment.

Keyword(s)

高山水文地質
熱示蹤劑
分散式光纖溫度感測器
地表水與地下水交互作用
裂隙岩體地下水流
alpine hydrogeology
heat tracer
fiberoptical distributed temperature sensor
surface water and groundwater interactions
groundwater flow in fractured rock

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Utilize Heat as a Tracer to Study the Characteristics of Groundwater Flow and Hydrological Cycle in Alpine Hydrogeology

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