| dc.description.abstract | Taiwan is a relatively water-deficient region, particularly during the summer and autumn seasons when rainfall is scarce, exacerbating the water shortage problem. In addition, recent years have seen abnormal weather patterns due to climate change, posing challenges such as supply-demand imbalances, uneven distribution of water resources, and water resource management issues for Taiwan.
This study utilizes the groundwater flow simulation program MODFLOW, developed by the United States Geological Survey (USGS), and employs the groundwater environment simulation software (GMS) to establish a numerical model for groundwater flow. The aim is to discuss the impact of agricultural water use on groundwater resources in the Meinong and Qishan areas. The simulation period for this study is 2020 and 2021. Hydrological and geographic data of the Pingtung Plain, including land use, rainfall, pumping, river flow, and hydraulic conductivity, are collected to establish groundwater models in the Meinong and Qishan areas, simulating existing agricultural water use and its effect on groundwater resources. The model verification results indicate that the correlation coefficient (R) is moderately correlated, except for the soil bank, with a value of 0.65, which is close to highly correlated. The remaining coefficients are greater than 0.7, indicating a high correlation. The root mean square error (RMSE) is approximately 1m.
The research findings demonstrate that, without irrigation, the recharge volume of the Meinong and Qishan irrigation districts in 2020 will be 16.94 million cubic meters, and the recharge volume of the Ligang irrigation district will be 2.37 million cubic meters. When considering irrigation, the recharge volume for the Meinong and Qishan irrigation districts is projected to be 19.11 million cubic meters, while the Ligang irrigation district is expected to have a recharge volume of 3.6 million cubic meters. In 2021, the recharge volume for the Meinong and Qishan irrigation districts will be 13.87 million cubic meters, with the Ligang irrigation district having a recharge volume of 2.08 million cubic meters. Considering irrigation, the recharge volume for the Meinong and Qishan irrigation districts is estimated to be 15.54 million cubic meters, while the Ligang irrigation district is anticipated to have a recharge volume of 3.26 million cubic meters.
Analysis of the trend from 2020 to 2021 reveals that the water storage changes in the Meinong and Qishan regions were negative regardless of irrigation, indicating that the decline was caused by water extraction. In the Ligang area, water storage changes showed an increasing trend in 2020 under irrigation conditions, yet the overall water storage change remained negative. However, in 2021, with the addition of irrigation water, the water storage change turned positive, demonstrating a significant replenishment effect. Based on the findings of this study, it can be concluded that irrigation can effectively contribute to underground water conservation to some extent. Therefore, proper irrigation design and management play a crucial role in water resource preservation. | en_US |