本研究將針對蘭陽溪流域，運用土地利用現況資料，探討改良之GWLF（Generalized Watershed Loading Function）水文模式模擬流量之精確度。由於GWLF模式計算方式在蒸發散以及垂直滲漏的部分計算較為簡單，修改滲漏的主要原因是因為模式高估了土壤的滲漏量，因此本研究修改GWLF水文模式中，有關蒸發散的計算以及滲漏計算的部分，並且探討修改後是否更加符合真實的滲漏情形。 根據分析結果顯示，修改後所得之GWLF模式可以更加準確的模擬蘭陽溪流量變化情形，平均月流量的R2值由0.85增加至0.92，效率係數由原本的0.78增加至0.91，因此改良後之模式能更精確的掌控月流量的變化情況。 This research focuses on the modification of GWLF (Generalized Watershed Loading Function) model. Because origin model overestimates vertical seepage, a modified vertical seepage and evapotranspiration component is suggest to enable the GWLF model to simulate the nature. The result indicated that the modified GWLF model could estimate the seepage and evapotranspiration more accurate. For the Lanyang River case study, R2 of average monthly streamflow is 0.92 (origin is 0.85 ), the coefficient of efficiency is 0.91(origin is 0.78 ). It is shown that modified GWLF model improve the accuracy in simulating the monthly streamflow.
