| 摘要: | 本研究為探討桃園工業港興建之海岸抽砂對海岸環境之影響，丹麥水力研究發展之mike21模式，用來讚算桃園海岸之波浪場，海流場及砂之擴散運輸場。探討抽京對海岸環境之影響範圍及停止抽砂後懸浮質濃度恢復至0.001Kg/m?3所需要的時間。 押砂引起之懸浮質運輸主要為風、波浪及海流等動力所造成，海流在退潮時為向北北東流最大流速約為1.2米/秒，漲潮時為向南南西流最大流速約為1.12米/秒，由於本水域以冬季之東北季風及波浪主道本水或之運輸，故夏季抽砂引起之懸浮質運輸對環境之衝擊較大。 以桃園工業港興建之海岸抽砂方式進行模擬，其結果為；開始抽砂後6天，其懸浮質濃度即達最大值0.061kg/m?3，其後即大值變化不大，亦最大值即在0.061kg/m?3附近除非海況有顯著改變。一旦發現其濃度超過允許要求，按本數值模擬結果，只要暫停抽砂30小時，其濃度即可由最大值0.061 kg/m?3恢復到0.001 kg/m?3之下。如以濃度大於0.002 kg/m?3為其抽砂對環境之影響範圍，則本抽砂情況對環境之影響範圍為夏季為由抽砂站之北方約8km，南方約5km，外海方向約7km，冬季為由抽砂站之北方約6.5km，南方約8km，外海方向約5.5km。
The fate of dredged material due to Tao Yuan industrial harbor construction, is found by numerical simulation. The model of MIKE21 is applied in this case. The fields of wave, ocean current and dredged material dispersion and transportation are established. The polluted area and the time needed that the concentration of dredged material decrease to 0.001 kg/m?3 after stop dredging, both are be discussed. The dominant energy of dredged material transport are wind, wave and ocean current. In this area, on ebb, the direction of current is NNE, the highest speed is 1.2 m/sec, on flood, the direction of current is SW. The highest current speed is 1.1m/sed. The NNE direction of winter wind and wave are dominant in this area. The effect of environment impact of dredge, the summer is heavier that winter. After 6 days continuous dredging, the concentration of dredged material is about 0.061 kg/m?3, this value is about the maximum concentration value, the more days dredging, the value will not be much more than that. If we stop dredge, the concentration of dredged material will decrease quickly, 30 hours later, the concentration down to less than 0.001 kg/m?3. It the concentration greater than 0.002 kg/m?3 is the polluted water of dredging, then the effect area of polluted in summer is to 8 km in NNE, 5 km in SSW, 7 km to offshore direction form dredging position and in winter is 6.5 km in NNE, 8 km in SSW, 5.5 km to the offshore direction. |
