地下水補注量評估在水資源的管理中是相當重要的，而各種評估地下水補注量的方法中，以地下水位變動法最易於計算。地下水位變動法的使用，是利用地下水位日抬升量與比出水率之乘積，以獲得地下水補注量，但由於現地比出水率不易獲得，若在沒有其他相關資料的輔助與修正下，利用地下水位變動法推估地下水補注量，易造成高估的現象。為合理推估地下水補注量，本研究主要藉由地下水位變動法結合消退曲線位移法來推估之，首先以地下水位變動法求得初始補注量參考值，將此參考值經由消退曲線位移法計算出對應的地下水排出量，以計算獲得的地下水排出量擬合河川流量的消退線段，並反覆調整地下水補注量參考值，當地下水排出量與河川流量在消退線段上達到擬合，即可獲得本研究結合模式之地下水補注量。本研究以蘭陽平原為研究區域，嘗試估計蘭陽溪流域地下水補注量。結果顯示，本研究利用結合模式之分析可獲得補注事件數量、各補注事件的補注時刻，與符合消退理論的地下水補注量，亦可求得該區域的比出水率範圍值，以期提供區域水資源管理研究之參考。另外，本文亦同時比較地下水位變動法、消退曲線位移法與本研究結合模式等三種方法，對於地下水補注量之評估結果顯示，地下水位變動法推估值較大，而消退曲線位移法與本研究之結合模式二種推估值較接近。 Groundwater recharge is an important component for water resource management. The method of water-table fluctuation coupling with groundwater daily rise and specific yield was one of the most facile methods to estimate groundwater recharge among various approaches. However, specific yield is difficult to obtain from real site. In order to improve the method of water-table fluctuation to estimate groundwater recharge, a composite method is provided to integrate recessioin-curve-displacement method. First of all, we get the result of initial groundwater recharge from the method of water-table fluctuation method. And then the initial groundwater recharge is used to calibrate the timing of groundwater discharge from the recessioin-curve-displacement method. After that, regulating groundwater recharge repeatedly until groundwater discharge is consistence with that calculated from recession segment of streamflow. The composite method is also applied to the case of Lanyang Plain area in Taiwan. Results showed the timing of recharge, recharge events, groundwater recharge, and the range of specific yield could be obtained by our composite method. This composite method is also compared with the method of water-table fluctuation and recession-curve-displacement method. The result indicates that the groundwater recharge values from composite method are quit close to those from recession-curve-displacement method. The values from water-table fluctuation method are bigger than those from other two methods.
