特定降雨事件下濁水溪沖積扇及名竹盆地地下水補注效益評估

Evaluation of groundwater recharge in Choushui river alluvial fan and Mingchu basin for specific rainfall events

林宗聖(Zong-sheng Lin)

指導教授 ： 陳瑞昇 ； 張誠信

國立中央大學/地球科學學院/應用地質研究所/碩士(2014年)

摘要

濁水溪沖積扇地區由於長年地下水缺乏妥善規劃及經營，造成嚴重地層下陷及海水入侵等危害，除了加強平原地區水資源管理外，位於南投縣名間鄉及竹山鎮間，濁水溪中游段的名竹盆地，主要由礫石層分佈，水文地質條件佳，若能了解本區地下水補注情形，則可更加妥善規劃地下水資源。本研究利用 FEMWATER 建立濁水溪沖積扇及名竹盆地三維地下水流模型，並進一步結合地表水數值模式進行模擬，探討特定降雨事件下地下水補注情況，其中特定降雨事件是以 2012 年梅雨及颱風所造成明顯降雨事件。以 GMS（Groundwater Modeling System）建構符合現地之模型，反應本區地下水流動情形。由研究結果顯示特定降雨事件後，含水層地下水垂直方向流動較水平方向流動明顯。淺層含水層受到降雨及土壤含水量影響，垂向流動分佈較廣。大量雨水經表土層入滲後集流，在名竹盆地及濁水溪沖
積扇扇頂地區深層含水層有明顯地下水垂向流動，成為下游含水層主要補注來源。抽水量對於地下水流動影響為次之，側向邊界對於地下水流動影響則不明顯。未來此區若進行地下水人工補注，可於區域內地下水垂向流動明顯之特定含水層進行，提升補注之效果，提供政府未來地下水補注規劃之參考。

關鍵字

濁水溪沖積扇 ； 名竹盆地 ； 補注機制 ； 地下水

並列摘要

Sound groundwater resources planning and management are lack in the Choushui River alluvial fan, resulting in the occurrence of serious land subsidence and seawater intrusion. Even the disasters induced by overpumping of groundwater pose a potential threat on the Taiwan High Speed Rail. In addition to improving the water resources management in the alluvial fan, the development of groundwater resources in the neighboring hills. Mingchu Basin, which is located on the midstream segment of the Choushui River and comprised of the gravel formation of Pleistocene, is an effective solution to resolve the problem in limited water resources. Because of wide drainage areas and good hydrogeological conditions, the Mingchu Basin is considered a high potential recharging region of groundwater. This work is to use the FEMWATER model equipped with the Groundwater Modeling System (GMS) to simulate the interaction of surface water and groundwater for specific three rainfall events. This study particularly focuses on the simulation of the groundwater flow, and evaluates the effect of different rainfall events on the groundwater recharge. The study results reveal that groundwater recharge and exchange are significant during the rainfall events and fast reduce after the rainfall events. The groundwater recharge is more easily fluctuated by the rainfall and soil water movement in the aquifer 1. The water movement in the vertical direction mainly occurs in the Mingchu Basin and apex of the Choushui River alluvial fan which located in the aquifer 2 and aquifer 3. The analyzed finding can provide residents with suggestive strategies to improve the water resources management. Government administrators with information of groundwater exchange between aquifers when plans of water resources are considered.

並列關鍵字

Choushui river alluvial fan ； Mingchu basin ； Recharge Mechanism ； FEMWATER ； Groundwater

參考文獻

〔30〕 許昊，「地下水補注量推估之研究-以濁水溪沖積扇為例」，國立臺灣大學生物環境系統工程學研究所，碩士論文，民國99年。

〔11〕 林宛蓉，「濁水溪沖積扇南緣地下水水位變化影響因子之關聯性研究」，國立成功大學地球科學研究所，碩士論文，民國96年。

〔13〕 陳冠宇，「應用地理資訊系統及因子分析方法於地下水補注潛勢評估─以濁水溪沖積扇為例」，國立交通大學土木工程系，碩士論文，民國99年。

〔14〕 王韋勳，「名竹盆地地下水流數值模式之建立及應用」，國立台灣大學土木工程研究所，碩士論文，民國101年。

〔16〕 Richards, L.A., 1931, “Capillary conduction of liquids through porous mediums”, Physics, 1, pp. 318-333.