- 學位論文
探討非飽和土壤參數對補注井之地下水補注成效之影響
Effects Of Unsaturated Soil Parameters On The Effectiveness Of Well Recharge
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摘要
由於台灣地理及氣象條件特殊，降雨型態分布不均及地形陡峭等因素，許多降雨無法被有效的利用即流入大海中，且台灣部分區域降雨量貧乏，使養殖業、農業用水需求量增加，超抽地下水，導致地下水位降低、海水入侵及地層下陷等問題。如何有效的執行地下水補注成為重要的議題。地下水補注為非飽和土壤滲流的問題，故本研究使用有限元素軟體ABAQUS來模擬人工補注井對一區域之蓄水層進行地下水補注之分析，將討論土壤不同的相對密度、補注井之深度及van Genuchten model參數α與n對地表高程變化及補注量之影響。由分析結果顯示蓄水層土壤於不同相對密度(30%、60%及90%)時，以相對密度30%的補注量最大，且蓄水層完成地下水補注所需之時間愈短。對地表隆起情形而言，蓄水層在愈疏鬆的情況下隆起量愈大，反之則愈小。在補注井深度影響方面，補注井深度愈深者，蓄水層完成地下水補注所需之時間愈短，且地表隆起量愈大，但對補注量則無明顯差異。在VG model之參數影響方面，當α值愈小時，補注量愈多，地表隆起量愈大，但蓄水層完成地下水補注所需之時間愈長；當n值愈小時，補注量愈多，地表隆起量愈大，對蓄水層完成補注所需的時間愈久。對於地表隆起量而言，當參數n減少40%時所產生之隆起量比參數α減少40%時來的明顯。
並列摘要
The distribution of rainfall is not uniform in Taiwan due to geographical and climatic condition. It happens that a lot of underused rainwater flows into the sea. When the consumption of water for aquaculture and agriculture increases, groundwater can be ultra-pumping. It will be the reason for reducing groundwater level, invading seawater, and soil settlement. Therefore, how to perform groundwater recharge effectively is an important issue. It is a coupled mechanical-seepage flow analysis in unsaturated soil for groundwater recharge. ABAQUS software was used to simulate a recharge well in a layer of aquifer. Parametric studies of recharge effectiveness were evaluated in this study. The influencing parameters include relative density of aquifer, the depth of recharge well and the values of unsaturated soil parameter α and n of van Genuchten model. The effects of these parameters on the amount of recharge and ground surface uplift were studied. The result shows that the amount of recharge increases and the duration of recharge decreases when relative density of aquifer reduces. The amount of uplift of ground surface increases due to the decrease of relative density. The duration of recharge is shorter and the amount of uplift of ground surface is large when the depth of recharge well is deeper. In unsaturated soil parameter of van Genuchten model, the amount of recharge and ground surface uplift are larger, the duration of recharge is longer when the values of α or n are small. The effect of the value of n on ground surface uplift is more than that of the value of α.
參考文獻
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