區域尺度的地下水模擬是分析水資源永續發展的重要工具，因為它可以評估不同類型地下水的含水層行為。台灣南部地區因為獨特的狹長地形與夏雨冬乾的氣候，論其用水來源，地下水絕對是不可忽視的水資源。然而研究區域高雄地區長期因不斷抽取地下水，已造成不可逆的環境問題。為此，基於物理的耦合地表-地下水數值模擬和監控機制可以有效解決此問題，同時擬定取水策略，以防止過度抽水情形。WASH123D是耦合一維(河川)、二維(地表逕流)與三維(地下水)的物理水文模型，可用於分析與流量和水質有關的問題。在本研究中，選擇WASH123D作為模擬台灣西南部地區2-D地表水和3-D地下水相互作用的工具。其中，水力參數(水力傳導係數和曼寧粗糙係數)是預先估算並選擇的；流域尺度的水力傳導係數(K)是採用低流量退水法估算；而乾旱季節的退水流量則使用物理半分佈式連續水文模型(HEC-HMS)模擬。透過鑽井和DEM兩種數據，開發了組合方法來合理估算有效含水層深度(D)，並且用於排除初始參數中的不確定性。採用所預估之流域尺度的K值於物理半分佈式水文模型進行模擬所得之數值與現場量測值相近，證明退水法分析是估算水文地質參數的有效方法。並且進一步用於建構露頭的形成和地質剖面的概念模型，以建立區域尺度的地下水模型. WASH123D以2-D/3-D非穩態模擬進行校準和驗證，選擇2017和2018年的兩次降雨事件來分析地下水位變化，不考慮抽水數據。通過六個統計指標的性能評估，證明了地下水位對降雨與水文反應的合理性。總體而言，在校準和驗證過程中，模擬和觀察到的地下水位明顯對應，表示WASH123D是研究所選區域地表與地下水相互作用的合適工具。WASH123D使用了一組經過校準和驗證的參數以完成包括抽水量在內的區域地下水系統模擬，進而利用抽水和降雨數據進行模擬抽水對區域地下水位的影響，以呈現含水層的補注和抽水現象的動態變化。 藉由觀測井連續地下水位的數據圖形，並根據地下水水位局部擾動震幅大小來確定含水層的性質(受壓或非受壓) ，驗證含水層對補注和抽水現象的反應。波峰和波谷的形狀代表含水層對補注和抽水現象的反應，而觀測井中水位波動提供了有關區域地下水的資訊。本研究展示WASH123D模式可描述地下水層受外部降雨、補注、抽水的影響，應該是未來研究地下水管理相關工作的可靠方法。建議針對本研究區域，可使用經過校準和驗證的參數來進行WASH123D模式模擬區域地下水系統，包含乾旱季節長時間的抽水量，以有效規劃和管理地下水資源。;Regional-scale groundwater modeling is a key tool for the sustainable development of water resources as it allows the assessment of the aquifer behavior under different types of hydrological stresses. Groundwater is a salient water resource in southern Taiwan, especially in Kaohsiung where underground water resources have been subject to incessant over pumping, resulted in non-reversible environmental issues. Physics-based integrated surface-subsurface numerical modeling with monitoring mechanisms effectively resolve this problem and support the design of water drawing policies to prevent over-pumping in any situation. WASH123D is a first-principle, integrated multimedia, multi-process, physics-based hydrology model, designed to answer the environmental issues concerning both water quantity and quality. In this study, WASH123D was selected as an appropriate protocol for the simulation of 2-D surface and 3-D groundwater interactions in the regional area of Southwest Taiwan. The hydraulic conductivity and overland Manning’s roughness coefficient were two selected hydraulic parameters. Catchment-scale hydraulic conductivity (K) was prior estimated using low flow recession technique. The recession flows during dry seasons were simulated using physically based, semi-distributed, continuous hydrological modeling (HEC-HMS). A combined approach was developed to reasonably estimate the effective aquifer depth (D) by employing borehole lithology and DEM data, and this new approach was used to eliminate the subjectivity in the initial guess of parameter, a problem that has been frequently encountered in previous studies. The estimated catchment-scale K values demonstrated that flow recession analysis is an effective method for estimating hydrogeological parameter through physically based semi-distributed hydrological modeling of ungauged creek catchments. The reference K values were comparable with the results of a field test and further used in the construction of conceptual model based on outcrop formation and geological cross-sections for regional-scale groundwater modeling. The calibration and validation of WASH123D were performed using 2-D/3-D transient simulation for the analysis of groundwater levels variations by selecting two-rainfall events in 2017 and 2018 without consideration of pumping data. The model performance evaluation through six statistical indicators to highest agreement indicated the reasonable hydrological response of groundwater levels to rainfall. Overall, the obvious corresponding of simulated and observed groundwater levels during calibration and validation indicated that WASH123D is an appropriate tool to investigate the surface-subsurface interaction in the selected study region. The set of calibrated and validated parameters were used to develop a full version of WASH123D including the pumping amount. This real-time simulation using pumping and rainfall data indicated the dynamics of recharge and discharge phenomena in the aquifer under pumping effects on regional groundwater levels. The aquifer response to recharge-discharge phenomena was investigated based on the shape of continuous groundwater level data from observation wells. The nature of aquifer (confined or unconfined) were identified based on the apparent line thickness of groundwater hydrograph. The shape of crest and trough represents the aquifer response to recharge-discharge phenomena. The knowledge of water level fluctuations in the observation wells provides a piece of prior information about the abstraction of groundwater. From the results achieved in this study, it is fruitful to represent WASH123D modeling as a next tool that can best describe aquifer response to external stresses and should be a credible approach for future research work related to groundwater management. The set of calibrated and validated parameters of the study region are recommended to be used to develop a full version of WASH123D including the pumping amount for a long period during the dry season for better groundwater resource planning and management.
