| 摘要: | 最近幾年，台灣的氣候型態呈現明顯的變化，主要表現在極端氣候事件的頻繁發生和降雨型態的劇烈變動。首先，極端氣候事件，如颱風、豪雨和極端高溫，呈現了增加的趨勢，其次，降雨型態的改變也是近年台灣氣候變化的一大特徵，乾旱危機也相繼爆發，造成水資源短缺，尤其對農業灌溉帶來重大影響，因此期望精確評估極端氣候和降雨型態改變對地下 水資源的衝擊，以發展更為有效的水資源管理策略。
本研究選用 MODFLOW 地下水數值模式，對高雄美濃、旗山地區進行地下水模擬，以探討氣候變遷下研究區域的地下水變化情形。本研究的模擬時間為 2015 年至 2023 年，模式再經過率定後採用相關係數及均方根誤差來評估率定結果。擬和結果顯示，相關性高，皆在 0.7 以上;方根誤差 除了吉洋為 1.51m 外，其餘皆在 1m 左右，顯示出本研究的地下水數值模 型能夠準確模擬實際的地下水位變化。
為了分析乾旱對地下水位變化的影響，利用 2020 年的乾旱情況來作為 未來乾旱年模擬的基準，設定初始水位、抽水量及水力傳導係數等參數， 再利用臺灣氣候變遷推估與資訊平台計畫(TCCIP)提供的耦合大氣-海洋- 陸面系統模式(GCMs)模擬未來氣候情境。結果顯示，隨著氣溫上升， 地下水位在不同情境下的變化有所不同，其中 TaiESM1 模型在 4°C 情境 下的地下水位升高，而 EC-Earth3 模型在 2°C 情境下的地下水位升高，顯 示不同模式對地下水補注的預測存在差異。因此，考慮更多的氣候模式及 情境，觀察降雨量的季節性分布及強度變化對地下水補注的影響，有助於 在針對乾旱及極端降雨事件時，能更有效地實施應對策略跟措施，以確保 地下水資源的可持續利用性。;In recent years, Taiwan′s climate pattern has shown significant changes, mainly in the frequency of extreme climate events and drastic changes in rainfall patterns. Firstly, extreme climate events, such as typhoons, heavy rainfall, and extreme high temperatures, have shown an increasing trend. Secondly, changes in rainfall patterns have also been a major feature of climate change in Taiwan in recent years. Droughts have erupted one after another, resulting in water scarcity, which has had a significant impact on agricultural irrigation in particular. Therefore, it is hoped that the impacts of the changes in extreme climatic conditions and rainfall patterns on groundwater resources will be assessed accurately, in order to develop more effective water resource management strategies.
In this study, the MODFLOW groundwater numerical model was employed to simulate groundwater changes in the Meinong and Qishan areas of Kaohsiung under climate change conditions. The simulation period spans from 2015 to 2023, and the model calibration was evaluated using correlation coefficients and root-mean-square errors (RMSE). The results showed that the correlation coefficients were all above 0.7, and the RMSE values were around 1 m, except for Jiyang, which had an RMSE of 1.51 m. This demonstrates that the numerical groundwater model can accurately simulate the actual changes in groundwater levels.
In order to analyze the effect of drought on groundwater level changes, the drought in 2020 was used as a benchmark for future drought years, and the initial water level, pumping volume, and hydraulic transmission coefficient were set to simulate future climate scenarios using the coupled atmosphere-ocean-surface system models (GCMs) provided by the Taiwan Climate Change Estimation and Information Platform (TCCIP) program. The results show that the changes in groundwater levels with increasing temperature vary under different scenarios, with the TaiESM1 model showing an increase in groundwater levels under the 4°C scenario and the EC-Earth3 model showing an increase in groundwater levels under the 2°C scenario, which indicates that there is a discrepancy in the prediction of groundwater recharge between different models. Therefore,considering more climate models and scenarios, and observing the impacts of seasonal distribution and intensity changes of rainfall on groundwater recharge can help to implement more effective response strategies and measures in response to droughts and extreme rainfall events, so as to ensure the sustainable utilization of groundwater resources. |
