以頻譜分析法評量地下水位時空變動

Spectral Analysis as a Tool to Estimate Spatiotemporal Changes of Groundwater Level

廖玲琬(Ling-Wan Liao) ； 洪銘堅(Ming-Jame Horng) ； 王逸民(Yet-Men Wang) ； 徐年盛(Nien-Sheng Hsu) ； 游雅淳(Ya-Chun Yu) ； 劉宏仁(Hung-Jen Liu)

《工程環境會刊》 28期 (2012/01) Pp. 1-14

https://doi.org/10.6562/JEE.2012.28.1

摘要

地下水含水層水位變動之影響因素主要包括地潮、海水感潮、降雨補注、大氣壓力、地震及人為抽用等，各項因子多具有特定頻率，本研究利用頻譜技術分析地下水水位紀錄，偵測各因子之頻率及其強度變化，以判定其影響程度，並解析地下水水位變動之複雜現象。其中之主要影響因子為人為抽水，頻譜分析顯示人為抽水多為一天1次之頻率，本研究已可歸納出養殖型、工業型、農業型、節費型與水塔型等五類。人為抽水行為造成地下水含水層水位下降，而天然補注使得水位回升，如此水位循環變動，形成一天1次之日變化。本研究擷取地下水時水位日變動大小之程度，稱之為抽補強度(Pumping Recovery Strength)，其數值越大代表密集抽水或補注不佳；數值越小則表示無明顯抽水或補注旺盛。藉分析地下水位觀測站抽補強度之時空分布，除可量化人為抽水影響之程度外，亦可作為地下水補注區位篩選之依據。

關鍵字

地下水水位 ； 頻譜技術 ； 抽補強度

並列摘要

Groundwater level fluctuation of aquifers is a result controlling by earth tide, sea tide, rainfall recharge, atmospheric pressure, earthquakes and artificial pumping. Many of the factors have specific frequencies; we can use spectrum technologies to analyze groundwater level records. The frequencies and each amplitudes of those factors can be detected. Thus the complex variations of groundwater level and its impact can be determined as well. Artificial pumping is identified as the main factor which has once per day frequency. Five typical pumping patterns are summarized to aquaculture, industry, agriculture, cost saving and water-tower. Groundwater level drawdown is caused by artificial pumping, and it's recharged naturally by rain and snow melt and to a smaller extent by surface water. This daily cyclic groundwater level variation is an once per day frequency. The magnitude of this change in groundwater level is called Pumping Recovery Strength (PRS) in this research. Higher PRS value represents intensive artificial pumping or poor recharging; lower PRS value means no obvious artificial pumping or strong recharging. Through temporal and spatial PRS distribution of groundwater observation stations, the infl uenced extent by artificial pumping can be quantified. It can also be used as base for groundwater recharge sites selecting.

並列關鍵字

groundwater level ； spectrum technologies ； pumping recovery strength