濁水溪沖積扇於颱風時期地表水與地下水交互機制之研究

A Study of Interaction Mechanism between Surface Water and Groundwater during Typhoon Period in Zhuoshui Alluvial Fan

陳威宇(Wei-Yu Chen)

指導教授 ： 張麗秋

淡江大學/工學院/水資源及環境工程學系碩士班/碩士(2015年)

https://doi.org/10.6846/TKU.2015.00356

摘要

地下水開發成本低，水質較不易受污染，且地下水的出水量穩定，對乾旱時期的供水具有非常大的價值。地下水流動慢、補注不易，若長期超限利用將會導致地下水源逐漸枯竭，造成地層下陷與海水入侵的嚴重災害，因此，倘能掌握地下水變動的情勢，將有助於地表水與地下水資源管理與調配運用。
本研究以濁水溪中上游山區與中下游沖積扇扇頂、扇央、扇尾為研究區域，以主成分分析、相關性分析與水收支平衡法探討颱風時期濁水溪沖積扇地表水與地下水交互作用，以瞭解濁水溪沖積扇降雨量對地下水補注之成效。
　　研究結果顯示：(1)綜合結果指出第一、二、三含水層受雨量補注之地下水上升延時依序約為2、6與30小時，呈現越深層含水層受降雨補注所需延時越長；颱風時期累積雨量山區達400mm且西螺200mm以上，可以有效的補注整個濁水溪沖積扇之地下水。(2)由主成分分析結果可得知第一含水層之第一主成分分數在西螺雨量站累積雨量達到20mm時開始上升，第三含水層之第一主成分在山區累積降雨量超過200mm時才會上升；(3)從相關性分析可得知第一含水層和第二含水層同一層地下水觀測井水位具有高度線性相關，與降雨多寡無關；第三含水層地下水位觀測井海園和海豐之水位相關性隨著累積雨量越高相關性也越高；(4)從水收支平衡法分析可觀察到地下水累積量越大，則第二含水層地下水位持續上升時間會越久；地下水累積量較少時，使得地下水移動速度緩慢，造成第三含水層之地下水位無法在4天內上升。

關鍵字

地下水 ； 成分分析 ； 相關性分析 ； 水收支平衡 ； 地表水與地下水交互機制

並列摘要

Groundwater is low cost, good water quality and sustained yield that is valuable for water supply during drought periods. Groundwater flow is slow and difficult to recharge, if long-term over-extraction will cause groundwater depletion gradually, land subsidence and salt-water intrusion. Therefore, analysis and assessment of trends in groundwater level can provide useful information for conjunctive management of surface water and groundwater.
　　In this study, Zhuoshui River is divided into two sub-areas, the alluvial fan area and mountainous area, to investigate interaction mechanism between surface water and groundwater during typhoon periods. The study uses principal component analysis, correlation analysis and water balance method to explore the effect of the amount of rain on groundwater level variation and recharge.
　　The results show that: (1) In the first, second and third aquifers, the time lag of groundwater recharge from rainfall were about 2, 6 and 30 hours, respectively. The accumulated amount of rain area reached 400mm and 200mm in the mountainous area and at Siluo rain gauge that can effectively recharge groundwater in the entire alluvial fan of Zhuoshi River.(2) From the principal component analysis, the first principal component scores of the first aquifer started rising when the accumulated amount of rain at Siluo rain gauge reached 20mm; those of the third aquifer started rising when the accumulated amount of rain in the mountainous area was over 200mm. (3) From correlation analysis, the water levels of groundwater observation wells of the same layer in the first and second aquifers water has highly linear correlation, regardless of the amount of rainfall. However, the correlation between the water levels of Haiyoun and Haifeng observation wells in third aquifer become higher when the accumulated amount of rain is higher. (4) From the water balance analysis, the greater accumulated amount of groundwater, the longer the second aquifer level rise lasting. When accumulated amount of groundwater are low, groundwater flow rate is slow that makes the third aquifer level cannot rise within four days.

並列關鍵字

Principal Component Analysis (PCA) ； Correlation analysis ； Water balance ； Interaction mechanisms

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