集集地震山崩對於溪頭實驗林區溪流水質之影響

本研究是調查與分析在集集大地震後，溪頭實驗林區北勢溪上游之二十處採樣點一年中的水質變化。其中有若干採樣點的間斷，是受山崩與道路封閉的影響。由實驗結果顯示，溪頭實驗林區雖然有大量的土石滑落，與植物的傾倒，但是在地震後各溪流水中的營養源、主要陰離子、重金屬、與水中懸浮性顆粒濃度，無論是在枯水或豐水期間，都沒有顯著增加的現象，證明在溪頭實驗林區內，經過集集地震的大變動，因植物的高覆蓋率與演替，使得溪頭實驗林區內的水中化學與物理因子流失量低。而在溪頭實驗林區外的各溪流水質，因受到土地使用較高的影響，尤其是人工種植茶樹、檳榔樹影響較多情況下，雖然在集集大地震後的枯水期間水質變化較不顯著，但是在四月初，即進入降雨期後，各支流的水中營養源，陰、陽離子，與懸浮性顆粒濃度就大量的增高。證明在不同的土地利用栽種，以及受到集集地震之巨大外力影響的變動下，明顯造成土壤中的化學性與物理性流失量突增。並同時亦發現，溪頭實驗林區內水中的硝酸氮濃度較高，這可能是導致林區大學池會有水質優養化的原因。

關鍵字

集集地震；溪頭實驗林區；北勢溪

並列摘要

After Chi-Chi earthquake, water quality in upper stream of Hsi-Tou Experimental Forest and Pei-Su Watershed has been investigated for one year. Twenty sampling sites were monitored in each tributary of Pei-Su River. Several monitoring sites were very difficult to reach due to landslide and road closing after the Chi-Chi earthquake. Experimental results show that concentrations of nutrient, major cations and anions, heavy metals and suspended solids did not increase significantly after the Chi-Chi earthquake. Even after the land sliding, ion leaching and soil erosion were not severe due to high covering rate of plants and recovering forest succession in Hsi-Tou Experimental Forest. Besides upper stream in the Hsi-Tou Experimental Forest, water quality in other tributaries of Pei-Su River did not show significant out flow during dry-period. But high concentrations of nutrients, major cations and anion, and suspended solids outflow during wet-period. Due to cultivation of tea and betel palm by local farmers, plant succession recovering is poor after earthquake landslides. Therefore, high degree of soil usage and cultivate short root plant cause more nutrient soil outflow by surface runoff in wet period. However, the nitrate concentrations were quite high in all monitoring sites during dry and wet periods. Large amount of nitrate flow into the University Pond in Hsi-Tou Experimental Forest may cause eutrophication and management problems in the future.

並列關鍵字

Chi-Chi earthquake ； Hsi-Tou Experimental Forest ； Pei-Su River

主題瀏覽