應用網格式地理資訊系統於土地利用變遷對地下水補注量影響之研究

Abstract

臺灣地區地下水的使用量約佔整體用水量的三分之一，為重要的水資源之一，而地下水資源要能永續利用，適當的資源評估及妥善的管理乃是不可或缺。地下水數值模式為地下水資源評估最主要的方法，其中補注量又為最重要的模式參數之一，因此區域地下水補注量的推估乃為地下水資源評估中關鍵的一環。 本研究目的在以python為主要開發平台，應用網格化後之土地利用、土壤及雨量等資訊，搭配網格式地理資訊系統(PCRaster)發展區域地下水補注量推估模式，並將此推估模式應用於屏東平原之區域地下水補注量推估，及探討土地利用變遷對該區域地下水補注量的影響。 屏東平原總面積約1234.26平方公里，其補注量推估結果顯示1999年至2010年之年總補注量約為12-20億噸，此12年的平均年補注量為17億噸，而該區域12年之平均年降雨量約為2415毫米，可計算得屏東平原年補注量約為年降雨量之57%。土地利用變遷前後補注量之差異分析結果指出，若透水區域轉為不透水區域之面積為屏東平原總面積之百分之十，則土地利用變遷前後地下水補注量之差異約為2億噸，此結果顯示隨著不透水面積上升，地下水補注量將隨之顯著降低。

The groundwater, providing fresh water for 1/3 of total water demand in Taiwan, is an important fresh water resource. Proper management is critical for sustainable use of the groundwater. Simulation models have been intensively used for the water resources evaluation. One of the most important factor is the groundwater recharge volume. This study uses python to develop a groundwater recharge evaluation platform which combines PCRaster software with raster-type data of land use, soil information, rainfall, etc. This platform is applied to estimate the groundwater recharge in Pingtung plain and study the influence of the land use associated with the groundwater recharge. The area of Pingtung plain is about 1234.26 km2. The annual groundwater recharge is between 1.2 and 2.0 billion tons of water during the period of 1999 through 2010. The average annual groundwater recharge is 1.7 billion tons with in the period. The annual precipitation in the period is 2415 mm. Accordingly, the recharge rate is about 57% in Pingtung plain. This study analyzes the relationship between the groundwater recharge and the land use. The result shows that 0.2 billion tons reduction of annual groundwater recharge if 10% of permeable land turns into impermeable. This result indicates significant impact on groundwater recharge associated with land use in Pingtung plain.